libreoffice base - Page 115

using xml type attribute for derived complex types

- by David Michel

Hi All, I'm trying to get derived complex types from a base type in an xsd schema. it works well when I do this (inspired by this): xml file: <person xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="Employee"> <name>John</name> <height>59</height> <jobDescription>manager</jobDescription> </person> xsd file: <xs:element name="person" type="Person"/> <xs:complexType name="Person" abstract="true"> <xs:sequence> <xs:element name= "name" type="xs:string"/> <xs:element name= "height" type="xs:double" /> </xs:sequence> </xs:complexType> <xs:complexType name="Employee"> <xs:complexContent> <xs:extension base="Person"> <xs:sequence> <xs:element name="jobDescription" type="xs:string" /> </xs:sequence> </xs:extension> </xs:complexContent> </xs:complexType> However, if I want to have the person element inside, for example, a sequence of another complex type, it doesn't work anymore: xml: <staffRecord> <company>mycompany</company> <dpt>sales</dpt> <person xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="Employee"> <name>John</name> <height>59</height> <jobDescription>manager</jobDescription> </person> </staffRecord> xsd file: <xs:element name="staffRecord"> <xs:complexType> <xs:sequence> <xs:element name="company" type="xs:string"/> <xs:element name="dpt" type="xs:string"/> <xs:element name="person" type="Person"/> <xs:complexType name="Person" abstract="true"> <xs:sequence> <xs:element name= "name" type="xs:string"/> <xs:element name= "height" type="xs:double" /> </xs:sequence> </xs:complexType> <xs:complexType name="Employee"> <xs:complexContent> <xs:extension base="Person"> <xs:sequence> <xs:element name="jobDescription" type="xs:string" /> </xs:sequence> </xs:extension> </xs:complexContent> </xs:complexType> </xs:sequence> </xs:complexType> </xs:element> When validating the xml with that schema with xmllint (under linux), I get this error message then: config.xsd:12: element complexType: Schemas parser error : Element '{http://www.w3.org/2001/XMLSchema}sequence': The content is not valid. Expected is (annotation?, (element | group | choice | sequence | any)*). WXS schema config.xsd failed to compile Any idea what is wrong ? David

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Why does BeginReceiveFrom never time out?

- by James Hugard

I am writing an asynchronous Ping using Raw Sockets in F#, to enable parallel requests using as few threads as possible ("System.Net.NetworkInformation.Ping" appears to use one thread per request, but have not tested this... also am interested in using F# async workflows). The synchronous version below correctly times out when the target host does not exist/respond, but the asynchronous version hangs. Both work when the host does respond... Any ideas? (note: the process must run as Admin for this code to work) This throws a timeout: let result = Ping.Ping ( IPAddress.Parse( "192.168.33.22" ), 1000 ) However, this hangs: let result = Ping.PingAsync ( IPAddress.Parse( "192.168.33.22" ), 1000 ) |> Async.RunSynchronously Here's the code... module Ping open System open System.Net open System.Net.Sockets open System.Threading //---- ICMP Packet Classes type IcmpMessage (t : byte) = let mutable m_type = t let mutable m_code = 0uy let mutable m_checksum = 0us member this.Type with get() = m_type member this.Code with get() = m_code member this.Checksum = m_checksum abstract Bytes : byte array default this.Bytes with get() = [| m_type m_code byte(m_checksum) byte(m_checksum >>> 8) |] member this.GetChecksum() = let mutable sum = 0ul let bytes = this.Bytes let mutable i = 0 // Sum up uint16s while i < bytes.Length - 1 do sum <- sum + uint32(BitConverter.ToUInt16( bytes, i )) i <- i + 2 // Add in last byte, if an odd size buffer if i <> bytes.Length then sum <- sum + uint32(bytes.[i]) // Shuffle the bits sum <- (sum >>> 16) + (sum &&& 0xFFFFul) sum <- sum + (sum >>> 16) sum <- ~~~sum uint16(sum) member this.UpdateChecksum() = m_checksum <- this.GetChecksum() type InformationMessage (t : byte) = inherit IcmpMessage(t) let mutable m_identifier = 0us let mutable m_sequenceNumber = 0us member this.Identifier = m_identifier member this.SequenceNumber = m_sequenceNumber override this.Bytes with get() = Array.append (base.Bytes) [| byte(m_identifier) byte(m_identifier >>> 8) byte(m_sequenceNumber) byte(m_sequenceNumber >>> 8) |] type EchoMessage() = inherit InformationMessage( 8uy ) let mutable m_data = Array.create 32 32uy do base.UpdateChecksum() member this.Data with get() = m_data and set(d) = m_data <- d this.UpdateChecksum() override this.Bytes with get() = Array.append (base.Bytes) (this.Data) //---- Synchronous Ping let Ping (host : IPAddress, timeout : int ) = let mutable ep = new IPEndPoint( host, 0 ) let socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let mutable buffer = packet.Bytes try if socket.SendTo( buffer, ep ) <= 0 then raise (SocketException()) buffer <- Array.create (buffer.Length + 20) 0uy let mutable epr = ep :> EndPoint if socket.ReceiveFrom( buffer, &epr ) <= 0 then raise (SocketException()) finally socket.Close() buffer //---- Entensions to the F# Async class to allow up to 5 paramters (not just 3) type Async with static member FromBeginEnd(arg1,arg2,arg3,arg4,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,iar,state)), endAction, ?cancelAction=cancelAction) static member FromBeginEnd(arg1,arg2,arg3,arg4,arg5,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,arg5,iar,state)), endAction, ?cancelAction=cancelAction) //---- Extensions to the Socket class to provide async SendTo and ReceiveFrom type System.Net.Sockets.Socket with member this.AsyncSendTo( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginSendTo, this.EndSendTo ) member this.AsyncReceiveFrom( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginReceiveFrom, (fun asyncResult -> this.EndReceiveFrom(asyncResult, remoteEP) ) ) //---- Asynchronous Ping let PingAsync (host : IPAddress, timeout : int ) = async { let ep = IPEndPoint( host, 0 ) use socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let outbuffer = packet.Bytes try let! result = socket.AsyncSendTo( outbuffer, 0, outbuffer.Length, SocketFlags.None, ep ) if result <= 0 then raise (SocketException()) let epr = ref (ep :> EndPoint) let inbuffer = Array.create (outbuffer.Length + 256) 0uy let! result = socket.AsyncReceiveFrom( inbuffer, 0, inbuffer.Length, SocketFlags.None, epr ) if result <= 0 then raise (SocketException()) return inbuffer finally socket.Close() }

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How to validate an xml with repeating child elements

- by gsk

I have an xml document with three child elements repeating in any order. I had element in the xsd because of which the xml doesn't get validated. I can not use because the elements occur more than once. Kindly help me on this. Here is the xml <Trailer> <TrailerField name="SegmentLabelOne" length="4" type="String">TSTS</TrailerField> <TrailerField name="SegmentLabelTwo" length="2" type="String">00</TrailerField> <CountItem length="10" type="Numeric">MT</CountItem> <TrailerField name="SegmentLabelThree" length="2" type="String">01</TrailerField> <CountItem length="10" type="Numeric">MA</CountItem> <TrailerField name="SegmentLabelFour" length="2" type="String">02</TrailerField> <TrailerField name="FilerOne" length="65" type="String"> </TrailerField> </Trailer> And here is the xsd <xsd:complexType name="TrailerSegment"> <xsd:sequence> <xsd:element name="NameOfElement" minOccurs="0" maxOccurs="unbounded"> <xsd:complexType> <xsd:simpleContent> <xsd:extension base="xsd:string"> <xsd:attribute name="name" type="xsd:string"></xsd:attribute> </xsd:extension> </xsd:simpleContent> </xsd:complexType> </xsd:element> <xsd:element name="CountItem" minOccurs="0" maxOccurs="unbounded"> <xsd:complexType> <xsd:simpleContent> <xsd:extension base="xsd:string"> <xsd:attribute name="length" type="xsd:string"></xsd:attribute> <xsd:attribute name="type" type="xsd:string"></xsd:attribute> </xsd:extension> </xsd:simpleContent> </xsd:complexType> </xsd:element> <xsd:element name="TrailerField" minOccurs="0" maxOccurs="unbounded"> <xsd:complexType> <xsd:simpleContent> <xsd:extension base="xsd:string"> <xsd:attribute name="name" type="xsd:string"></xsd:attribute> <xsd:attribute name="length" type="xsd:string"></xsd:attribute> <xsd:attribute name="type" type="xsd:string"></xsd:attribute> </xsd:extension> </xsd:simpleContent> </xsd:complexType> </xsd:element> </xsd:sequence> </xsd:complexType>

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Partial generic type inference possible in C#?

- by Lasse V. Karlsen

I am working on rewriting my fluent interface for my IoC class library, and when I refactored some code in order to share some common functionality through a base class, I hit upon a snag. Note: This is something I want to do, not something I have to do. If I have to make do with a different syntax, I will, but if anyone has an idea on how to make my code compile the way I want it, it would be most welcome. I want some extension methods to be available for a specific base-class, and these methods should be generic, with one generic type, related to an argument to the method, but the methods should also return a specific type related to the particular descendant they're invoked upon. Better with a code example than the above description methinks. Here's a simple and complete example of what doesn't work: using System; namespace ConsoleApplication16 { public class ParameterizedRegistrationBase { } public class ConcreteTypeRegistration : ParameterizedRegistrationBase { public void SomethingConcrete() { } } public class DelegateRegistration : ParameterizedRegistrationBase { public void SomethingDelegated() { } } public static class Extensions { public static ParameterizedRegistrationBase Parameter<T>( this ParameterizedRegistrationBase p, string name, T value) { return p; } } class Program { static void Main(string[] args) { ConcreteTypeRegistration ct = new ConcreteTypeRegistration(); ct .Parameter<int>("age", 20) .SomethingConcrete(); // <-- this is not available DelegateRegistration del = new DelegateRegistration(); del .Parameter<int>("age", 20) .SomethingDelegated(); // <-- neither is this } } } If you compile this, you'll get: 'ConsoleApplication16.ParameterizedRegistrationBase' does not contain a definition for 'SomethingConcrete' and no extension method 'SomethingConcrete'... 'ConsoleApplication16.ParameterizedRegistrationBase' does not contain a definition for 'SomethingDelegated' and no extension method 'SomethingDelegated'... What I want is for the extension method (Parameter<T>) to be able to be invoked on both ConcreteTypeRegistration and DelegateRegistration, and in both cases the return type should match the type the extension was invoked on. The problem is as follows: I would like to write: ct.Parameter<string>("name", "Lasse") ^------^ notice only one generic argument but also that Parameter<T> returns an object of the same type it was invoked on, which means: ct.Parameter<string>("name", "Lasse").SomethingConcrete(); ^ ^-------+-------^ | | +---------------------------------------------+ .SomethingConcrete comes from the object in "ct" which in this case is of type ConcreteTypeRegistration Is there any way I can trick the compiler into making this leap for me? If I add two generic type arguments to the Parameter method, type inference forces me to either provide both, or none, which means this: public static TReg Parameter<TReg, T>( this TReg p, string name, T value) where TReg : ParameterizedRegistrationBase gives me this: Using the generic method 'ConsoleApplication16.Extensions.Parameter<TReg,T>(TReg, string, T)' requires 2 type arguments Using the generic method 'ConsoleApplication16.Extensions.Parameter<TReg,T>(TReg, string, T)' requires 2 type arguments Which is just as bad. I can easily restructure the classes, or even make the methods non-extension-methods by introducing them into the hierarchy, but my question is if I can avoid having to duplicate the methods for the two descendants, and in some way declare them only once, for the base class. Let me rephrase that. Is there a way to change the classes in the first code example above, so that the syntax in the Main-method can be kept, without duplicating the methods in question? The code will have to be compatible with both C# 3.0 and 4.0. Edit: The reason I'd rather not leave both generic type arguments to inference is that for some services, I want to specify a parameter value for a constructor parameter that is of one type, but pass in a value that is a descendant. For the moment, matching of specified argument values and the correct constructor to call is done using both the name and the type of the argument. Let me give an example: ServiceContainerBuilder.Register<ISomeService>(r => r .From(f => f.ConcreteType<FileService>(ct => ct .Parameter<Stream>("source", new FileStream(...))))); ^--+---^ ^---+----^ | | | +- has to be a descendant of Stream | +- has to match constructor of FileService If I leave both to type inference, the parameter type will be FileStream, not Stream.

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Uninitialized constant Item::Types

- by Rasmus

Hi! First of, im a newbie ruby programmer so please bare with me if this is a very dumb question. I get this uninitialized constant error when i submit my nested forms. order.rb class Order < ActiveRecord::Base has_many :items, :dependent => :destroy has_many :types, :through => :items accepts_nested_attributes_for :items accepts_nested_attributes_for :types validates_associated :items validates_associated :types end item.rb class Item < ActiveRecord::Base has_one :types belongs_to :order accepts_nested_attributes_for :types validates_associated :types end type.rb class Type < ActiveRecord::Base belongs_to :items belongs_to :orders end new.erb.html <% form_for @order do |f| %> <%= f.error_messages %> <% f.fields_for :items do |builder| %> <table border="0"> <th>Type</th> <th>Amount</th> <th>Text</th> <th>Price</th> <tr> <% f.fields_for :type do |m| %> <td> <%= m.collection_select :type, Type.find(:all, :order => "created_at DESC"), :id, :name, {:prompt => "Select a Type" }, {:id => "selector", :onchange => "type_change(this)"} %> </td> <% end %> <td> <%= f.text_field :amount, :id => "amountField", :onchange => "change_total_price()" %> </td> <td> <%= f.text_field :text, :id => "textField" %> </td> <td> <%= f.text_field :price, :class => "priceField", :onChange => "change_total_price()" %> </td> <td> <%= link_to_remove_fields "Remove Item", f %> </td> </tr> </table> <% end %> <p><%= link_to_add_fields "Add Item", f, :items %></p> <p> <%= f.label :total_price %><br /> <%= f.text_field :total_price, :class => "priceField", :id => "totalPrice" %> </p> <p><%= f.submit "Create"%></p> <% end %> <%= link_to 'Back', orders_path %> create method in orders_controller.rb def create @order = Order.new(params[:order]) respond_to do |format| if @order.save flash[:notice] = 'Post was successfully created.' format.html { redirect_to(@order) } format.xml { render :xml => @order, :status => :created, :location => @order } else format.html { render :action => "new" } format.xml { render :xml => @order.errors, :status => :unprocessable_entity } end end end Hopefully you can see what i cant

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Architecture for Qt SIGNAL with subclass-specific, templated argument type

- by Barry Wark

I am developing a scientific data acquisition application using Qt. Since I'm not a deep expert in Qt, I'd like some architecture advise from the community on the following problem: The application supports several hardware acquisition interfaces but I would like to provide an common API on top of those interfaces. Each interface has a sample data type and a units for its data. So I'm representing a vector of samples from each device as a std::vector of Boost.Units quantities (i.e. std::vector<boost::units::quantity<unit,sample_type> >). I'd like to use a multi-cast style architecture, where each data source broadcasts newly received data to 1 or more interested parties. Qt's Signal/Slot mechanism is an obvious fit for this style. So, I'd like each data source to emit a signal like typedef std::vector<boost::units::quantity<unit,sample_type> > SampleVector signals: void samplesAcquired(SampleVector sampleVector); for the unit and sample_type appropriate for that device. Since tempalted QObject subclasses aren't supported by the meta-object compiler, there doesn't seem to be a way to have a (tempalted) base class for all data sources which defines the samplesAcquired Signal. In other words, the following won't work: template<T,U> //sample type and units class DataSource : public QObject { Q_OBJECT ... public: typedef std::vector<boost::units::quantity<U,T> > SampleVector signals: void samplesAcquired(SampleVector sampleVector); }; The best option I've been able to come up with is a two-layered approach: template<T,U> //sample type and units class IAcquiredSamples { public: typedef std::vector<boost::units::quantity<U,T> > SampleVector virtual shared_ptr<SampleVector> acquiredData(TimeStamp ts, unsigned long nsamples); }; class DataSource : public QObject { ... signals: void samplesAcquired(TimeStamp ts, unsigned long nsamples); }; The samplesAcquired signal now gives a timestamp and number of samples for the acquisition and clients must use the IAcquiredSamples API to retrieve those samples. Obviously data sources must subclass both DataSource and IAcquiredSamples. The disadvantage of this approach appears to be a loss of simplicity in the API... it would be much nicer if clients could get the acquired samples in the Slot connected. Being able to use Qt's queued connections would also make threading issues easier instead of having to manage them in the acquiredData method within each subclass. One other possibility, is to use a QVariant argument. This necessarily puts the onus on subclass to register their particular sample vector type with Q_REGISTER_METATYPE/qRegisterMetaType. Not really a big deal. Clients of the base class however, will have no way of knowing what type the QVariant value type is, unless a tag struct is also passed with the signal. I consider this solution at least as convoluted as the one above, as it forces clients of the abstract base class API to deal with some of the gnarlier aspects of type system. So, is there a way to achieve the templated signal parameter? Is there a better architecture than the one I've proposed?

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Cannot find Package fop ( Ithink)

- by efendioglu

Hello friends I try to use fop engine programatically I search for an example and I find this class import java.io.File; import java.io.IOException; import java.io.OutputStream; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerFactory; import javax.xml.transform.TransformerException; import javax.xml.transform.Source; import javax.xml.transform.Result; import javax.xml.transform.stream.StreamSource; import javax.xml.transform.sax.SAXResult; import org.apache.avalon.framework.ExceptionUtil; import org.apache.avalon.framework.logger.ConsoleLogger; import org.apache.avalon.framework.logger.Logger; import org.apache.fop.apps.Driver; import org.apache.fop.apps.FOPException; import org.apache.fop.messaging.MessageHandler; public class Invokefop { public void convertXML2PDF(File xml, File xslt, File pdf) throws IOException, FOPException, TransformerException { Driver driver = new Driver(); Logger logger = new ConsoleLogger(ConsoleLogger.LEVEL_INFO); driver.setLogger(logger); MessageHandler.setScreenLogger(logger); driver.setRenderer(Driver.RENDER_PDF); OutputStream out = new java.io.FileOutputStream(pdf); try { driver.setOutputStream(out); TransformerFactory factory = TransformerFactory.newInstance(); Transformer transformer = factory.newTransformer(new StreamSource(xslt)); Source src = new StreamSource(xml); Result res = new SAXResult(driver.getContentHandler()); transformer.transform(src, res); } finally { out.close(); } } public static void main(String[] args) { try { System.out.println("JAVA XML2PDF:: FOP ExampleXML2PDF\n"); System.out.println("JAVA XML2PDF:: Preparing..."); File base = new File("../"); File baseDir = new File(base, "in"); File outDir = new File(base, "out"); outDir.mkdirs(); File xmlfile = new File(baseDir, args[0]); File xsltfile = new File(baseDir, args[1]); File pdffile = new File(outDir, args[2]); System.out.println("JAVA XML2PDF:: Input: XML (" + xmlfile + ")"); System.out.println("JAVA XML2PDF:: Stylesheet: " + xsltfile); System.out.println("JAVA XML2PDF:: Output: PDF (" + pdffile + ")"); System.out.println(); System.out.println("JAVA XML2PDF:: Transforming..."); Invokefop app = new Invokefop(); app.convertXML2PDF(xmlfile, xsltfile, pdffile); System.out.println("JAVA XML2PDF:: Success!"); } catch (Exception e) { System.err.println(ExceptionUtil.printStackTrace(e)); System.exit(-1); } } } All the Libs from Fop are in the Classpath including the fop.jar in build directory. After I run thejavac Invokefop.java I get this error: > C:\....\fop>javac Invokefop.java Invokefop.java:21: cannot find symbol symbol : class Driver location: package org.apache.fop.apps import org.apache.fop.apps.Driver; ^ Invokefop.java:23: package org.apache.fop.messaging does not exist import org.apache.fop.messaging.MessageHandler; ^ Invokefop.java:31: cannot find symbol symbol : class Driver location: class Invokefop Driver driver = new Driver(); ^ Invokefop.java:31: cannot find symbol symbol : class Driver location: class Invokefop Driver driver = new Driver(); ^ Invokefop.java:36: cannot find symbol symbol : variable MessageHandler location: class Invokefop MessageHandler.setScreenLogger(logger); ^ Invokefop.java:39: cannot find symbol symbol : variable Driver location: class Invokefop driver.setRenderer(Driver.RENDER_PDF); ^ 6 errors I am relatively new to Java, but with this approach I try to execute the fop engine in c++ using this java class.. Have anybody some Idea, how to solve this errors... Thanx in advance..

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How to generate a Program template by generating an abstract class

- by Byron-Lim Timothy Steffan

i have the following problem. The 1st step is to implement a program, which follows a specific protocol on startup. Therefore, functions as onInit, onConfigRequest, etc. will be necessary. (These are triggered e.g. by incoming message on a TCP Port) My goal is to generate a class for example abstract one, which has abstract functions as onInit(), etc. A programmer should just inherit from this base class and should merely override these abstract functions of the base class. The rest as of the protocol e.g. should be simply handled in the background (using the code of the base class) and should not need to appear in the programmers code. What is the correct design strategy for such tasks? and how do I deal with, that the static main method is not inheritable? What are the key-tags for this problem? (I have problem searching for a solution since I lack clear statements on this problem) Goal is to create some sort of library/class, which - included in ones code - results in executables following the protocol. EDIT (new explanation): Okay let me try to explain more detailled: In this case programs should be clients within a client server architecture. We have a client server connection via TCP/IP. Each program needs to follow a specific protocol upon program start: As soon as my program starts and gets connected to the server it will receive an Init Message (TcpClient), when this happens it should trigger the function onInit(). (Should this be implemented by an event system?) After onInit() a acknowledgement message should be sent to the server. Afterwards there are some other steps as e.g. a config message from the server which triggers an onConfig and so on. Let's concentrate on the onInit function. The idea is, that onInit (and onConfig and so on) should be the only functions the programmer should edit while the overall protocol messaging is hidden for him. Therefore, I thought using an abstract class with the abstract methods onInit(), onConfig() in it should be the right thing. The static Main class I would like to hide, since within it e.g. there will be some part which connects to the tcp port, which reacts on the Init Message and which will call the onInit function. 2 problems here: 1. the static main class cant be inherited, isn it? 2. I cannot call abstract functions from the main class in the abstract master class. Let me give an Pseudo-example for my ideas: public abstract class MasterClass { static void Main(string[] args){ 1. open TCP connection 2. waiting for Init Message from server 3. onInit(); 4. Send Acknowledgement, that Init Routine has ended successfully 5. waiting for Config message from server 6..... } public abstract void onInit(); public abstract void onConfig(); } I hope you get the idea now! The programmer should afterwards inherit from this masterclass and merely need to edit the functions onInit and so on. Is this way possible? How? What else do you recommend for solving this? EDIT: The strategy ideo provided below is a good one! Check out my comment on that.

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has_one and has_many associations: which side of the association is saved first

- by SeeBees

I have three simplified models: class Team < ActiveRecord::Base has_many :players has_one :coach end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end I use the following code to test these models: t = Team.new team.coach = Coach.new team.save! team.save! returns true. But in another test: t = Team.new team.players << Player.new team.save! team.save! gives the following error: > ActiveRecord::RecordInvalid: > Validation failed: Players is invalid > from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/validations.rb:1090:in > `save_without_dirty!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/dirty.rb:87:in `save_without_transactions!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in > `transaction' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:182:in > `transaction' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:208:in > `rollback_active_record_state!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from (irb):14 I figured out when team.save! is called, it first calls player.save!. player needs to validate the presence of the id of the associated team. But at the time player.save! is called, team hasn't been saved yet, and therefore, team_id doesn't yet exist for player. This fails the player's validation, so the error occurs. But on the other hand, team is saved before coach.save!, otherwise the first example will get the same error as the second. So I've concluded that when a has_many bs, a.save! will save bs prior to a. When a has_one b, a.save! will save a prior to b. If I am right, why is this the case? It doesn't seem logical to me. Why has_one and has_many association have different order in saving? Any ideas? Thanks.

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Ruby on Rails is complaining about a method that doesn't exist that is built into Active Record. Wha

- by grg-n-sox

This will probably just be a simple problem and I am just blind or an idiot but I could use some help. So I am going over some basic guides in Rails, reviewing the basics and such for an upcoming exam. One of the guides included was the sort-of-standard getting started guide over at guide.rubyonrails.org. Here is the link if you need it. Also all my code is for my app is from there, so I have no problem releasing any of my code since it should be the same as shown there. I didn't do a copy paste, but I basically was typing with Vim in one half of my screen and the web page in the other half, typing what I see. http://guides.rubyonrails.org/getting_started.html So like I said, I am going along the guide when I noticed past a certain point in the tutorial, I was always getting an error on the site. To find the section of code, just hit Ctrl+f on the page (or whatever you have search/find set to) and enter "accepts_". This should immediately direct you to this chunk of code. class Post < ActiveRecord::Base validates_presence_of :name, :title validates_length_of :title, :minimum => 5 has_many :comments has_many :tags accepts_nested_attributes_for :tags, :allow_destroy => :true , :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } } end So I tried putting this in my code. It is in ~/Rails/blog/app/models/post.rb in case you are wondering. However, even after all the other code I put in past that in the guide, hoping I was just missing some line of code that would come up later in the guide. But nothing, same error every time. This is what I get. NoMethodError in PostsController#index undefined method `accepts_nested_attributes_for' for #<Class:0xb7109f98> /usr/lib/ruby/gems/1.8/gems/activerecord-2.2.2/lib/active_record/base.rb:1833:in `method_missing' app/models/post.rb:7 app/controllers/posts_controller.rb:9:in `index' Request Parameters: None Response Headers: {"Content-Type"=>"", "cookie"=>[], "Cache-Control"=>"no-cache"} Now, I copied the above code from the guide. The two code sections I edited mentioned in the error message I will paste as is below. class PostsController < ApplicationController # GET /posts # GET /posts.xml before_filter :find_post, :only => [:show, :edit, :update, :destroy] def index @posts = Post.find(:all) # <= the line 9 referred to in error message respond_to do |format| format.html # index.html.erb format.xml { render :xml => @posts } end end class Post < ActiveRecord::Base validates_presence_of :name, :title validates_length_of :title, :minimum => 5 has_many :comments has_many :tags accepts_nested_attributes_for :tags, :allow_destroy => :true , # <= problem :reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } } end Also here is gem local gem list. I do note that they are a bit out of date, but the default Rails install any of the school machines (an environment likely for my exam) is basically 'gem install rails --version 2.2.2' and since they are windows machines, they come with all the normal windows ruby gems that comes with the ruby installer. However, I am running this off a Debian virtual machine of mine, but trying to set it up similarly and I figured the windows ruby gems wouldn't change anything in Rails. *** LOCAL GEMS *** actionmailer (2.2.2) actionpack (2.2.2) activerecord (2.2.2) activeresource (2.2.2) activesupport (2.2.2) gem_plugin (0.2.3) hpricot (0.8.2) linecache (0.43) log4r (1.1.7) ptools (1.1.9) rack (1.1.0) rails (2.2.2) rake (0.8.7) sqlite3-ruby (1.2.3) So any ideas on what the problem is? Thanks in advanced.

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How do I use accepts_nested_attributes_for?

- by Angela

Editing my question for conciseness and to update what I've done: How do I model having multiple Addresses for a Company and assign a single Address to a Contact, and be able to assign them when creating or editing a Contact? I want to use nested attributes to be able to add an address at the time of creating a new contact. That address exists as its own model because I may want the option to drop-down from existing addresses rather than entering from scratch. I can't seem to get it to work. I get a undefined method `build' for nil:NilClass error Here is my model for Contacts: class Contact < ActiveRecord::Base attr_accessible :first_name, :last_name, :title, :phone, :fax, :email, :company, :date_entered, :campaign_id, :company_name, :address_id, :address_attributes belongs_to :company belongs_to :address accepts_nested_attributes_for :address end Here is my model for Address: class Address < ActiveRecord::Base attr_accessible :street1, :street2, :city, :state, :zip has_many :contacts end I would like, when creating an new contact, access all the Addresses that belong to the other Contacts that belong to the Company. So here is how I represent Company: class Company < ActiveRecord::Base attr_accessible :name, :phone, :addresses has_many :contacts has_many :addresses, :through => :contacts end Here is how I am trying to create a field in the View for _form for Contact so that, when someone creates a new Contact, they pass the address to the Address model and associate that address to the Contact: <% f.fields_for :address, @contact.address do |builder| %> <p> <%= builder.label :street1, "Street 1" %> </br> <%= builder.text_field :street1 %> <p> <% end %> When I try to Edit, the field for Street 1 is blank. And I don't know how to display the value from show.html.erb. At the bottom is my error console -- can't seem to create values in the address table: My Contacts controller is as follows: def new @contact = Contact.new @contact.address.build # Iundefined method `build' for nil:NilClass @contact.date_entered = Date.today @campaigns = Campaign.find(:all, :order => "name") if params[:campaign_id].blank? else @campaign = Campaign.find(params[:campaign_id]) @contact.campaign_id = @campaign.id end if params[:company_id].blank? else @company = Company.find(params[:company_id]) @contact.company_name = @company.name end end def create @contact = Contact.new(params[:contact]) if @contact.save flash[:notice] = "Successfully created contact." redirect_to @contact else render :action => 'new' end end def edit @contact = Contact.find(params[:id]) @campaigns = Campaign.find(:all, :order => "name") end Here is a snippet of my error console: I am POSTING the attribute, but it is not CREATING in the Address table.... Processing ContactsController#create (for 127.0.0.1 at 2010-05-12 21:16:17) [POST] Parameters: {"commit"="Submit", "authenticity_token"="d8/gx0zy0Vgg6ghfcbAYL0YtGjYIUC2b1aG+dDKjuSs=", "contact"={"company_name"="Allyforce", "title"="", "campaign_id"="2", "address_attributes"={"street1"="abc"}, "fax"="", "phone"="", "last_name"="", "date_entered"="2010-05-12", "email"="", "first_name"="abc"}} Company Load (0.0ms)[0m [0mSELECT * FROM "companies" WHERE ("companies"."name" = 'Allyforce') LIMIT 1[0m Address Create (16.0ms)[0m [0;1mINSERT INTO "addresses" ("city", "zip", "created_at", "street1", "updated_at", "street2", "state") VALUES(NULL, NULL, '2010-05-13 04:16:18', NULL, '2010-05-13 04:16:18', NULL, NULL)[0m Contact Create (0.0ms)[0m [0mINSERT INTO "contacts" ("company", "created_at", "title", "updated_at", "campaign_id", "address_id", "last_name", "phone", "fax", "company_id", "date_entered", "first_name", "email") VALUES(NULL, '2010-05-13 04:16:18', '', '2010-05-13 04:16:18', 2, 2, '', '', '', 5, '2010-05-12', 'abc', '')[0m

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wxPthon problems with Wrapping StaticText

- by Scott B

Hello. I am having an issue with wxPython. A simplified version of the code is posted below (white space, comments, etc removed to reduce size - but the general format to my program is kept roughly the same). When I run the script, the static text correctly wraps as it should, but the other items in the panel do not move down (they act as if the statictext is only one line and thus not everything is visible). If I manually resize the window/frame, even just a tiny amount, everything gets corrected and displays as it is should. I took screen shots to show this behavior, but I just created this account and thus don't have the required 10 reputation points to be allowed to post pictures. Why does it not display correctly to begin with? I've tried all sorts of combination's of GetParent().Refresh() or Update() and GetTopLevelParent().Update() or Refresh(). I've tried everything I can think of but cannot get it to display correctly without manually resizing the frame/window. Once re-sized, it works exactly as I want it to. Information: Windows XP Python 2.5.2 wxPython 2.8.11.0 (msw-unicode) Any suggestions? Thanks! Code: #! /usr/bin/python import wx class StaticWrapText(wx.PyControl): def __init__(self, parent, id=wx.ID_ANY, label='', pos=wx.DefaultPosition, size=wx.DefaultSize, style=wx.NO_BORDER, validator=wx.DefaultValidator, name='StaticWrapText'): wx.PyControl.__init__(self, parent, id, pos, size, style, validator, name) self.statictext = wx.StaticText(self, wx.ID_ANY, label, style=style) self.wraplabel = label #self.wrap() def wrap(self): self.Freeze() self.statictext.SetLabel(self.wraplabel) self.statictext.Wrap(self.GetSize().width) self.Thaw() def DoGetBestSize(self): self.wrap() #print self.statictext.GetSize() self.SetSize(self.statictext.GetSize()) return self.GetSize() class TestPanel(wx.Panel): def __init__(self, *args, **kwargs): # Init the base class wx.Panel.__init__(self, *args, **kwargs) self.createControls() def createControls(self): # --- Panel2 ------------------------------------------------------------- self.Panel2 = wx.Panel(self, -1) msg1 = 'Below is a List of Files to be Processed' staticBox = wx.StaticBox(self.Panel2, label=msg1) Panel2_box1_v1 = wx.StaticBoxSizer(staticBox, wx.VERTICAL) Panel2_box2_h1 = wx.BoxSizer(wx.HORIZONTAL) Panel2_box3_v1 = wx.BoxSizer(wx.VERTICAL) self.wxL_Inputs = wx.ListBox(self.Panel2, wx.ID_ANY, style=wx.LB_EXTENDED) sz = dict(size=(120,-1)) wxB_AddFile = wx.Button(self.Panel2, label='Add File', **sz) wxB_DeleteFile = wx.Button(self.Panel2, label='Delete Selected', **sz) wxB_ClearFiles = wx.Button(self.Panel2, label='Clear All', **sz) Panel2_box3_v1.Add(wxB_AddFile, 0, wx.TOP, 0) Panel2_box3_v1.Add(wxB_DeleteFile, 0, wx.TOP, 0) Panel2_box3_v1.Add(wxB_ClearFiles, 0, wx.TOP, 0) Panel2_box2_h1.Add(self.wxL_Inputs, 1, wx.ALL|wx.EXPAND, 2) Panel2_box2_h1.Add(Panel2_box3_v1, 0, wx.ALL|wx.EXPAND, 2) msg = 'This is a long line of text used to test the autowrapping ' msg += 'static text message. ' msg += 'This is a long line of text used to test the autowrapping ' msg += 'static text message. ' msg += 'This is a long line of text used to test the autowrapping ' msg += 'static text message. ' msg += 'This is a long line of text used to test the autowrapping ' msg += 'static text message. ' staticMsg = StaticWrapText(self.Panel2, label=msg) Panel2_box1_v1.Add(staticMsg, 0, wx.ALL|wx.EXPAND, 2) Panel2_box1_v1.Add(Panel2_box2_h1, 1, wx.ALL|wx.EXPAND, 0) self.Panel2.SetSizer(Panel2_box1_v1) # --- Combine Everything ------------------------------------------------- final_vbox = wx.BoxSizer(wx.VERTICAL) final_vbox.Add(self.Panel2, 1, wx.ALL|wx.EXPAND, 2) self.SetSizerAndFit(final_vbox) class TestFrame(wx.Frame): def __init__(self, *args, **kwargs): # Init the base class wx.Frame.__init__(self, *args, **kwargs) panel = TestPanel(self) self.SetClientSize(wx.Size(500,500)) self.Center() class wxFileCleanupApp(wx.App): def __init__(self, *args, **kwargs): # Init the base class wx.App.__init__(self, *args, **kwargs) def OnInit(self): # Create the frame, center it, and show it frame = TestFrame(None, title='Test Frame') frame.Show() return True if __name__ == '__main__': app = wxFileCleanupApp() app.MainLoop() EDIT: See my post below for a solution that works!

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When saving a model with has_one or has_many associations, which side of the association is saved fi

- by SeeBees

I have three simplified models: class Team < ActiveRecord::Base has_many :players has_one :coach end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end I use the following code to test these models: t = Team.new team.coach = Coach.new team.save! team.save! returns true. But in another test: t = Team.new team.players << Player.new team.save! team.save! gives the following error: > ActiveRecord::RecordInvalid: > Validation failed: Players is invalid > from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/validations.rb:1090:in > `save_without_dirty!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/dirty.rb:87:in `save_without_transactions!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/connection_adapters/abstract/database_statements.rb:136:in > `transaction' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:182:in > `transaction' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:208:in > `rollback_active_record_state!' from > /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.4/lib/active_record/transactions.rb:200:in > `save!' from (irb):14 I figured out that when team.save! is called, it first calls player.save!. player needs to validate the presence of the id of the associated team. But at the time player.save! is called, team hasn't been saved yet, and therefore, team_id doesn't yet exist for player. This fails the player's validation, so the error occurs. But on the other hand, team is saved before coach.save!, otherwise the first example will get the same error as the second one. So I've concluded that when a has_many bs, a.save! will save bs prior to a. When a has_one b, a.save! will save a prior to b. If I am right, why is this the case? It doesn't seem logical to me. Why do has_one and has_many association have different order in saving? Any ideas? And is there any way I can change the order? Say I want to have the same saving order for both has_one and has_many. Thanks.

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Rails ActiveRecord friendly code from a Complex Join, Sum, and Group query

- by Chad M

PROBLEM Hello, I am having no luck trying to break down this SQL statement into ActiveRecord/Rails friendly code and I'd like to learn how I can avoid a find_by_sql statement in this situation. Scenario I have users that create audits when they perform an action. Each audit is of a specific audit_activity. Each audit_activity is worth a certain number of points, based on score_weight. I need to find the total scores of each user, based on their total accumulated audit_activity score_weights. Eventually I'll need to rank them which means adding a sort to this as well. My Code Here is my sql and simplified versions of the tables in question. Any thoughts? SQL with full column names (for clarity) SELECT users.id, u.email, SUM(audit_activity.score_weight) FROM users JOIN audits ON users.id = audits.user_id JOIN audit_activities ON audit_activities.id = audits.audit_activity_id GROUP BY users.id; Models: User, Audit, AuditActivity User fields: id, email class User < ActiveRecord::Base include Clearance::User has_many :audits end Audit fields: id, user_id, audit_activity_id class Audit < ActiveRecord::Base belongs_to :user belongs_to :audit_activity end AuditActivity fields: id, score_weight class AuditActivity < ActiveRecord::Base has_many :audits end Example Data Here is a set of SQL statements so you can play with similar data I'm working with and see what comes up when the concerned query is run. You should just be able to copy/paste the whole thing into a database query browser. CREATE TABLE users( id INTEGER NOT NULL, email TEXT (25), PRIMARY KEY (id) ); CREATE TABLE audits( id INTEGER NOT NULL, user_id INTEGER, audit_activity_id INTEGER, PRIMARY KEY (id) ); CREATE TABLE audit_activities( id INTEGER NOT NULL, score_weight INTEGER, PRIMARY KEY (id) ); INSERT INTO users(id, email) VALUES(1, "[email protected]"); INSERT INTO users(id, email) VALUES(2, "[email protected]"); INSERT INTO users(id, email) VALUES(3, "[email protected]"); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(1, 1, 1); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(2, 1, 2); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(3, 1, 1); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(4, 1, 3); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(5, 1, 1); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(6, 1, 4); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(7, 2, 4); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(8, 2, 4); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(9, 2, 4); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(10, 3, 3); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(11, 3, 2); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(12, 3, 2); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(13, 3, 2); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(14, 3, 3); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(15, 3, 1); INSERT INTO audits(id, user_id, audit_activity_id) VALUES(16, 3, 1); INSERT INTO audit_activities(id, score_weight) VALUES(1, 1); INSERT INTO audit_activities(id, score_weight) VALUES(2, 2); INSERT INTO audit_activities(id, score_weight) VALUES(3, 7); INSERT INTO audit_activities(id, score_weight) VALUES(4, 11); The Query Again, here is the query. SELECT u.id, u.email, SUM(aa.score_weight) FROM users u JOIN audits a ON u.id = a.user_id JOIN audit_activities aa ON aa.id = a.audit_activity_id GROUP BY u.id; Many Thanks, Chad

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wpf custom control problem

- by josika

Hi! I have a problem, and I have not found the solution yet. I woud like to create a base custom control and use it in another custom control. The base control work fine when I use in a window, but when I use in the other custom control, the binding does not work. What's wrong with my code? Code: Model: public class ElementModel { public string Name { get; set; } public string FullName { get; set; } } The base control: public class ListControl : Control { static ListControl() { DefaultStyleKeyProperty.OverrideMetadata(typeof(ListControl), new FrameworkPropertyMetadata(typeof(ListControl))); } public ListControl() { SetValue(ElementListProperty, new List<ElementModel>()); } public static readonly DependencyProperty ElementListProperty = DependencyProperty.Register( "ElementList", typeof(List<ElementModel>), typeof(ListControl), new FrameworkPropertyMetadata(new List<ElementModel>()) ); public List<ElementModel> ElementList { get { return (List<ElementModel>)GetValue(ElementListProperty); } set { SetValue(ElementListProperty, value); } } } The Wrapper Control: public class ListWrapper : Control { static ListWrapper() { DefaultStyleKeyProperty.OverrideMetadata(typeof(ListWrapper), new FrameworkPropertyMetadata(typeof(ListWrapper))); } public ListWrapper() { SetValue(EMListProperty, new List<ElementModel>()); } public static readonly DependencyProperty EMListProperty = DependencyProperty.Register( "EMList", typeof(List<ElementModel>), typeof(ListWrapper), new FrameworkPropertyMetadata(new List<ElementModel>()) ); public List<ElementModel> EMList { get { return (List<ElementModel>)GetValue(EMListProperty); } set { SetValue(EMListProperty, value); } } } Generic.xaml <ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:UIControl"> <Style TargetType="{x:Type local:ListControl}"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type local:ListControl}"> <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}"> <ListBox ItemsSource="{TemplateBinding ElementList}"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel> <Label Content="Name:"/> <TextBlock Text="{Binding Path=Name}" /> <Label Content="Full name:"/> <TextBlock Text="{Binding Path=FullName}" /> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Border> </ControlTemplate> </Setter.Value> </Setter> </Style> <Style TargetType="{x:Type local:ListWrapper}"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="{x:Type local:ListWrapper}"> <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}"> <local:ListControl ElementList="{TemplateBinding EMList}" /> </Border> </ControlTemplate> </Setter.Value> </Setter> </Style> If I put the controls in the window and binding properties, than the ListControl works fine and shows the elements, but the WrapperList does not. <Window x:Class="MainApplication.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:ui="clr-namespace:UIControl;assembly=UIControl" Title="Window1" Height="304" Width="628"> <Grid> <ui:ListControl x:Name="listCtr" ElementList="{Binding Path=EList}" HorizontalAlignment="Left" Width="300" /> <ui:ListWrapper x:Name="listWrp" EMList="{Binding Path=EList}" HorizontalAlignment="Right" Width="300" Background="Gray"/> </Grid> Project archive

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C++ templated factory constructor/de-serialization

- by KRao

Hi, I was looking at the boost serialization library, and the intrusive way to provide support for serialization is to define a member function with signature (simplifying): class ToBeSerialized { public: //Define this to support serialization //Notice not virtual function! template<class Archive> void serialize(Archive & ar) {.....} }; Moreover, one way to support serilization of derived class trough base pointers is to use a macro of the type: //No mention to the base class(es) from which Derived_class inherits BOOST_CLASS_EXPORT_GUID(Derived_class, "derived_class") where Derived_class is some class which is inheriting from a base class, say Base_class. Thanks to this macro, it is possible to serialize classes of type Derived_class through pointers to Base_class correctly. The question is: I am used in C++ to write abstract factories implemented through a map from std::string to (pointer to) functions which return objects of the desired type (and eveything is fine thanks to covariant types). Hover I fail to see how I could use the above non-virtual serialize template member function to properly de-serialize (i.e. construct) an object without knowing its type (but assuming that the type information has been stored by the serializer, say in a string). What I would like to do (keeping the same nomenclature as above) is something like the following: XmlArchive xmlArchive; //A type or archive xmlArchive.open("C:/ser.txt"); //Contains type information for the serialized class Base_class* basePtr = Factory<Base_class>::create("derived_class",xmlArchive); with the function on the righ-hand side creating an object on the heap of type Derived_class (via default constructor, this is the part I know how to solve) and calling the serialize function of xmlArchive (here I am stuck!), i.e. do something like: Base_class* Factory<Base_class>::create("derived_class",xmlArchive) { Base_class* basePtr = new Base_class; //OK, doable, usual map string to pointer to function static_cast<Derived_class*>( basePtr )->serialize( xmlArchive ); //De-serialization, how????? return basePtr; } I am sure this can be done (boost serialize does it but its code is impenetrable! :P), but I fail to figure out how. The key problem is that the serialize function is a template function. So I cannot have a pointer to a generic templated function. As the point in writing the templated serialize function is to make the code generic (i.e. not having to re-write the serialize function for different Archivers), it does not make sense then to have to register all the derived classes for all possible archive types, like: MY_CLASS_REGISTER(Derived_class, XmlArchive); MY_CLASS_REGISTER(Derived_class, TxtArchive); ... In fact in my code I relies on overloading to get the correct behaviour: void serialize( XmlArchive& archive, Derived_class& derived ); void serialize( TxtArchive& archive, Derived_class& derived ); ... The key point to keep in mind is that the archive type is always known, i.e. I am never using runtime polymorphism for the archive class...(again I am using overloading on the archive type). Any suggestion to help me out? Thank you very much in advance! Cheers

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SOAP and NHibernate Session in C#

- by Anonymous Coward

In a set of SOAP web services the user is authenticated with custom SOAP header (username/password). Each time the user call a WS the following Auth method is called to authenticate and retrieve User object from NHibernate session: [...] public Services : Base { private User user; [...] public string myWS(string username, string password) { if( Auth(username, password) ) { [...] } } } public Base : WebService { protected static ISessionFactory sesFactory; protected static ISession session; static Base { Configuration conf = new Configuration(); [...] sesFactory = conf.BuildSessionFactory(); } private bool Auth(...) { session = sesFactory.OpenSession(); MembershipUser user = null; if (UserCredentials != null && Membership.ValidateUser(username, password)) { luser = Membership.GetUser(username); } ... try { user = (User)session.Get(typeof(User), luser.ProviderUserKey.ToString()); } catch { user = null; throw new [...] } return user != null; } } When the WS work is done the session is cleaned up nicely and everything works: the WSs create, modify and change objects and Nhibernate save them in the DB. The problems come when an user (same username/password) calls the same WS at same time from different clients (machines). The state of the saved objects are inconsistent. How do I manage the session correctly to avoid this? I searched and the documentation about Session management in NHibernate is really vast. Should I Lock over user object? Should I set up a "session share" management between WS calls from same user? Should I use Transaction in some savvy way? Thanks Update1 Yes, mSession is 'session'. Update2 Even with a non-static session object the data saved in the DB are inconsistent. The pattern I use to insert/save object is the following: var return_value = [...]; try { using(ITransaction tx = session.Transaction) { tx.Begin(); MyType obj = new MyType(); user.field = user.field - obj.field; // The fields names are i.e. but this is actually what happens. session.Save(user); session.Save(obj); tx.Commit(); return_value = obj.another_field; } } catch ([...]) { // Handling exceptions... } finally { // Clean up session.Flush(); session.Close(); } return return_value; All new objects (MyType) are correctly saved but the user.field status is not as I would expect. Even obj.another_field is correct (the field is an ID with generated=on-save policy). It is like 'user.field = user.field - obj.field;' is executed more times then necessary.

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Windows opaque UserControl not refreshing any graphical changes made on it

- by Debajyoti Das

I have created a Windows UserControl. It actually paints a Grid (i.e. vertical and horizontal lines) using Graphics. User can change each cell height and width, and according to that Grid is refreshed. Overriding the OnPaint event I have created the grid. I used SetStyle(ControlStyles.Opaque, true) to make it transparent. I used this control on a form and from there I change the values of the cell height and width but due to Opaque the new grid is overlapping on the previous one and making it clumsy. How do I resolve this? UserControl Code: public partial class Grid : UserControl { public Grid() { InitializeComponent(); SetStyle(ControlStyles.Opaque, true); } private float _CellWidth = 10, _CellHeight = 10; private Color _GridColor = Color.Black; public float CellWidth { get { return this._CellWidth; } set { this._CellWidth = value; } } public float CellHeight { get { return this._CellHeight; } set { this._CellHeight = value; } } public Color GridColor { get { return this._GridColor; } set { this._GridColor = value; } } protected override void OnPaint(PaintEventArgs e) { base.OnPaint(e); Graphics g; float iHeight = this.Height; float iWidth = this.Width; g = e.Graphics; Pen myPen = new Pen(GridColor); myPen.Width = 1; if (this.CellWidth > 0 && this.CellHeight > 0) { for (float X = 0; X <= iWidth; X += this.CellWidth) { g.DrawLine(myPen, X, 0, X, iHeight); } for (float Y = 0; Y <= iHeight; Y += this.CellHeight) { g.DrawLine(myPen, 0, Y, iWidth, Y); } } } public override void Refresh() { base.ResumeLayout(true); base.Refresh(); ResumeLayout(true); } } Form Code: public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { } private void btnBrowse_Click(object sender, EventArgs e) { try { if (ofdImage.ShowDialog() == System.Windows.Forms.DialogResult.OK) { pbImage.Image = Image.FromFile(ofdImage.FileName); } } catch (Exception ex) { MessageBox.Show(ex.Message); } } private void btnShowGrid_Click(object sender, EventArgs e) { if (grid1.Visible) { grid1.Visible = false; btnShowGrid.Text = "Show"; } else { grid1.Visible = true; btnShowGrid.Text = "Hide"; } } private void btnGridCellMaximize_Click(object sender, EventArgs e) { grid1.CellHeight += 1; grid1.CellWidth += 1; grid1.Refresh(); } private void btnGridCellMinimize_Click(object sender, EventArgs e) { grid1.CellHeight -= 1; grid1.CellWidth -= 1; grid1.Refresh(); } }

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How to reserve public API to internal usage in .NET?

- by mark

Dear ladies and sirs. Let me first present the case, which will explain my question. This is going to be a bit long, so I apologize in advance :-). I have objects and collections, which should support the Merge API (it is my custom API, the signature of which is immaterial for this question). This API must be internal, meaning only my framework should be allowed to invoke it. However, derived types should be able to override the basic implementation. The natural way to implement this pattern as I see it, is this: The Merge API is declared as part of some internal interface, let us say IMergeable. Because the interface is internal, derived types would not be able to implement it directly. Rather they must inherit it from a common base type. So, a common base type is introduced, which would implement the IMergeable interface explicitly, where the interface methods delegate to respective protected virtual methods, providing the default implementation. This way the API is only callable by my framework, but derived types may override the default implementation. The following code snippet demonstrates the concept: internal interface IMergeable { void Merge(object obj); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } void IMergeable.Merge(object obj) { Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } All is fine, provided a single common base type suffices, which is usually true for non collection types. The thing is that collections must be mergeable as well. Collections do not play nicely with the presented concept, because developers do not develop collections from the scratch. There are predefined implementations - observable, filtered, compound, read-only, remove-only, ordered, god-knows-what, ... They may be developed from scratch in-house, but once finished, they serve wide range of products and should never be tailored to some specific product. Which means, that either: they do not implement the IMergeable interface at all, because it is internal to some product the scope of the IMergeable interface is raised to public and the API becomes open and callable by all. Let us refer to these collections as standard collections. Anyway, the first option screws my framework, because now each possible standard collection type has to be paired with the respective framework version, augmenting the standard with the IMergeable interface implementation - this is so bad, I am not even considering it. The second option breaks the framework as well, because the IMergeable interface should be internal for a reason (whatever it is) and now this interface has to open to all. So what to do? My solution is this. make IMergeable public API, but add an extra parameter to the Merge method, I call it a security token. The interface implementation may check that the token references some internal object, which is never exposed to the outside. If this is the case, then the method was called from within the framework, otherwise - some outside API consumer attempted to invoke it and so the implementation can blow up with a SecurityException. Here is the modified code snippet demonstrating this concept: internal static class InternalApi { internal static readonly object Token = new object(); } public interface IMergeable { void Merge(object obj, object token); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } public void Merge(object obj, object token) { if (!object.ReferenceEquals(token, InternalApi.Token)) { throw new SecurityException("bla bla bla"); } Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } Of course, this is less explicit than having an internally scoped interface and the check is moved from the compile time to run time, yet this is the best I could come up with. Now, I have a gut feeling that there is a better way to solve the problem I have presented. I do not know, may be using some standard Code Access Security features? I have only vague understanding of it, but can LinkDemand attribute be somehow related to it? Anyway, I would like to hear other opinions. Thanks.

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Azure - Part 4 - Table Storage Service in Windows Azure

- by Shaun

In Windows Azure platform there are 3 storage we can use to save our data on the cloud. They are the Table, Blob and Queue. Before the Chinese New Year Microsoft announced that Azure SDK 1.1 had been released and it supports a new type of storage – Drive, which allows us to operate NTFS files on the cloud. I will cover it in the coming few posts but now I would like to talk a bit about the Table Storage. Concept of Table Storage Service The most common development scenario is to retrieve, create, update and remove data from the data storage. In the normal way we communicate with database. When we attempt to move our application over to the cloud the most common requirement should be have a storage service. Windows Azure provides a in-build service that allow us to storage the structured data, which is called Windows Azure Table Storage Service. The data stored in the table service are like the collection of entities. And the entities are similar to rows or records in the tradtional database. An entity should had a partition key, a row key, a timestamp and set of properties. You can treat the partition key as a group name, the row key as a primary key and the timestamp as the identifer for solving the concurrency problem. Different with a table in a database, the table service does not enforce the schema for tables, which means you can have 2 entities in the same table with different property sets. The partition key is being used for the load balance of the Azure OS and the group entity transaction. As you know in the cloud you will never know which machine is hosting your application and your data. It could be moving based on the transaction weight and the number of the requests. If the Azure OS found that there are many requests connect to your Book entities with the partition key equals “Novel” it will move them to another idle machine to increase the performance. So when choosing the partition key for your entities you need to make sure they indecate the category or gourp information so that the Azure OS can perform the load balance as you wish. Consuming the Table Although the table service looks like a database, you cannot access it through the way you are using now, neither ADO.NET nor ODBC. The table service exposed itself by ADO.NET Data Service protocol, which allows you can consume it through the RESTful style by Http requests. The Azure SDK provides a sets of classes for us to connect it. There are 2 classes we might need: TableServiceContext and TableServiceEntity. The TableServiceContext inherited from the DataServiceContext, which represents the runtime context of the ADO.NET data service. It provides 4 methods mainly used by us: CreateQuery: It will create a IQueryable instance from a given type of entity. AddObject: Add the specified entity into Table Service. UpdateObject: Update an existing entity in the Table Service. DeleteObject: Delete an entity from the Table Service. Beofre you operate the table service you need to provide the valid account information. It’s something like the connect string of the database but with your account name and the account key when you created the storage service on the Windows Azure Development Portal. After getting the CloudStorageAccount you can create the CloudTableClient instance which provides a set of methods for using the table service. A very useful method would be CreateTableIfNotExist. It will create the table container for you if it’s not exsited. And then you can operate the eneities to that table through the methods I mentioned above. Let me explain a bit more through an exmaple. We always like code rather than sentence. Straightforward Accessing to the Table Here I would like to build a WCF service on the Windows Azure platform, and for now just one requirement: it would allow the client to create an account entity on the table service. The WCF service would have a method named Register and accept an instance of the account which the client wants to create. After perform some validation it will add the entity into the table service. So the first thing I should do is to create a Cloud Application on my VIstial Studio 2010 RC. (The Azure SDK 1.1 only supports VS2008 and VS2010 RC.) The solution should be like this below. Then I added a configuration items for the storage account through the Settings section under the cloud project. (Double click the Services file under Roles folder and navigate to the Setting section.) This setting will be used when to retrieve my storage account information. Since for now I just in the development phase I will select “UseDevelopmentStorage=true”. And then I navigated to the WebRole.cs file under my WCF project. If you have read my previous posts you would know that this file defines the process when the application start, and terminate on the cloud. What I need to do is to when the application start, set the configuration publisher to load my config file with the config name I specified. So the code would be like below. I removed the original service and contract created by the VS template and add my IAccountService contract and its implementation class - AccountService. And I add the service method Register with the parameters: email, password and it will return a boolean value to indicates the result which is very simple. At this moment if I press F5 the application will be established on my local development fabric and I can see my service runs well through the browser. Let’s implement the service method Rigister, add a new entity to the table service. As I said before the entities you want to store in the table service must have 3 properties: partition key, row key and timespan. You can create a class with these 3 properties. The Azure SDK provides us a base class for that named TableServiceEntity in Microsoft.WindowsAzure.StorageClient namespace. So what we need to do is more simply, create a class named Account and let it derived from the TableServiceEntity. And I need to add my own properties: Email, Password, DateCreated and DateDeleted. The DateDeleted is a nullable date time value to indecate whether this entity had been deleted and when. Do you notice that I missed something here? Yes it’s the partition key and row key I didn’t assigned. The TableServiceEntity base class defined 2 constructors one was a parameter-less constructor which will be used to fill values into the properties from the table service when retrieving data. The other was one with 2 parameters: partition key and row key. As I said below the partition key may affect the load balance and the row key must be unique so here I would like to use the email as the parition key and the email plus a Guid as the row key. OK now we finished the entity class we need to store onto the table service. The next step is to create a data access class for us to add it. Azure SDK gives us a base class for it named TableServiceContext as I mentioned below. So let’s create a class for operate the Account entities. The TableServiceContext need the storage account information for its constructor. It’s the combination of the storage service URI that we will create on Windows Azure platform, and the relevant account name and key. The TableServiceContext will use this information to find the related address and verify the account to operate the storage entities. Hence in my AccountDataContext class I need to override this constructor and pass the storage account into it. All entities will be saved in the table storage with one or many tables which we call them “table containers”. Before we operate an entity we need to make sure that the table container had been created on the storage. There’s a method we can use for that: CloudTableClient.CreateTableIfNotExist. So in the constructor I will perform it firstly to make sure all method will be invoked after the table had been created. Notice that I passed the storage account enpoint URI and the credentials to specify where my storage is located and who am I. Another advise is that, make your entity class name as the same as the table name when create the table. It will increase the performance when you operate it over the cloud especially querying. Since the Register WCF method will add a new account into the table service, here I will create a relevant method to add the account entity. Before implement, I should add a reference - System.Data.Services.Client to the project. This reference provides some common method within the ADO.NET Data Service which can be used in the Windows Azure Table Service. I will use its AddObject method to create my account entity. Since the table service are not fully implemented the ADO.NET Data Service, there are some methods in the System.Data.Services.Client that TableServiceContext doesn’t support, such as AddLinks, etc. Then I implemented the serivce method to add the account entity through the AccountDataContext. You can see in the service implmentation I load the storage account information through my configuration file and created the account table entity from the parameters. Then I created the AccountDataContext. If it’s my first time to invoke this method the constructor of the AccountDataContext will create a table container for me. Then I use Add method to add the account entity into the table. Next, let’s create a farely simple client application to test this service. I created a windows console application and added a service reference to my WCF service. The metadata information of the WCF service cannot be retrieved if it’s deployed on the Windows Azure even though the <serviceMetadata httpGetEnabled="true"/> had been set. If we need to get its metadata we can deploy it on the local development service and then changed the endpoint to the address which is on the cloud. In the client side app.config file I specified the endpoint to the local development fabric address. And the just implement the client to let me input an email and a password then invoke the WCF service to add my acocunt. Let’s run my application and see the result. Of course it should return TRUE to me. And in the local SQL Express I can see the data had been saved in the table. Summary In this post I explained more about the Windows Azure Table Storage Service. I also created a small application for demostration of how to connect and consume it through the ADO.NET Data Service Managed Library provided within the Azure SDK. I only show how to create an eneity in the storage service. In the next post I would like to explain about how to query the entities with conditions thruogh LINQ. I also would like to refactor my AccountDataContext class to make it dyamic for any kinds of entities. Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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Passing multiple simple POST Values to ASP.NET Web API

- by Rick Strahl

A few weeks backs I posted a blog post about what does and doesn't work with ASP.NET Web API when it comes to POSTing data to a Web API controller. One of the features that doesn't work out of the box - somewhat unexpectedly - is the ability to map POST form variables to simple parameters of a Web API method. For example imagine you have this form and you want to post this data to a Web API end point like this via AJAX: <form> Name: <input type="name" name="name" value="Rick" /> Value: <input type="value" name="value" value="12" /> Entered: <input type="entered" name="entered" value="12/01/2011" /> <input type="button" id="btnSend" value="Send" /> </form> <script type="text/javascript"> $("#btnSend").click( function() { $.post("samples/PostMultipleSimpleValues?action=kazam", $("form").serialize(), function (result) { alert(result); }); }); </script> or you might do this more explicitly by creating a simple client map and specifying the POST values directly by hand:$.post("samples/PostMultipleSimpleValues?action=kazam", { name: "Rick", value: 1, entered: "12/01/2012" }, $("form").serialize(), function (result) { alert(result); }); On the wire this generates a simple POST request with Url Encoded values in the content:POST /AspNetWebApi/samples/PostMultipleSimpleValues?action=kazam HTTP/1.1 Host: localhost User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:15.0) Gecko/20100101 Firefox/15.0.1 Accept: application/json Connection: keep-alive Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Referer: http://localhost/AspNetWebApi/FormPostTest.html Content-Length: 41 Pragma: no-cache Cache-Control: no-cachename=Rick&value=12&entered=12%2F10%2F2011 Seems simple enough, right? We are basically posting 3 form variables and 1 query string value to the server. Unfortunately Web API can't handle request out of the box. If I create a method like this:[HttpPost] public string PostMultipleSimpleValues(string name, int value, DateTime entered, string action = null) { return string.Format("Name: {0}, Value: {1}, Date: {2}, Action: {3}", name, value, entered, action); }You'll find that you get an HTTP 404 error and { "Message": "No HTTP resource was found that matches the request URI…"} Yes, it's possible to pass multiple POST parameters of course, but Web API expects you to use Model Binding for this - mapping the post parameters to a strongly typed .NET object, not to single parameters. Alternately you can also accept a FormDataCollection parameter on your API method to get a name value collection of all POSTed values. If you're using JSON only, using the dynamic JObject/JValue objects might also work. ModelBinding is fine in many use cases, but can quickly become overkill if you only need to pass a couple of simple parameters to many methods. Especially in applications with many, many AJAX callbacks the 'parameter mapping type' per method signature can lead to serious class pollution in a project very quickly. Simple POST variables are also commonly used in AJAX applications to pass data to the server, even in many complex public APIs. So this is not an uncommon use case, and - maybe more so a behavior that I would have expected Web API to support natively. The question "Why aren't my POST parameters mapping to Web API method parameters" is already a frequent one… So this is something that I think is fairly important, but unfortunately missing in the base Web API installation. Creating a Custom Parameter Binder Luckily Web API is greatly extensible and there's a way to create a custom Parameter Binding to provide this functionality! Although this solution took me a long while to find and then only with the help of some folks Microsoft (thanks Hong Mei!!!), it's not difficult to hook up in your own projects. It requires one small class and a GlobalConfiguration hookup. Web API parameter bindings allow you to intercept processing of individual parameters - they deal with mapping parameters to the signature as well as converting the parameters to the actual values that are returned. Here's the implementation of the SimplePostVariableParameterBinding class:public class SimplePostVariableParameterBinding : HttpParameterBinding { private const string MultipleBodyParameters = "MultipleBodyParameters"; public SimplePostVariableParameterBinding(HttpParameterDescriptor descriptor) : base(descriptor) { } /// <summary> /// Check for simple binding parameters in POST data. Bind POST /// data as well as query string data /// </summary> public override Task ExecuteBindingAsync(ModelMetadataProvider metadataProvider, HttpActionContext actionContext, CancellationToken cancellationToken) { // Body can only be read once, so read and cache it NameValueCollection col = TryReadBody(actionContext.Request); string stringValue = null; if (col != null) stringValue = col[Descriptor.ParameterName]; // try reading query string if we have no POST/PUT match if (stringValue == null) { var query = actionContext.Request.GetQueryNameValuePairs(); if (query != null) { var matches = query.Where(kv => kv.Key.ToLower() == Descriptor.ParameterName.ToLower()); if (matches.Count() > 0) stringValue = matches.First().Value; } } object value = StringToType(stringValue); // Set the binding result here SetValue(actionContext, value); // now, we can return a completed task with no result TaskCompletionSource<AsyncVoid> tcs = new TaskCompletionSource<AsyncVoid>(); tcs.SetResult(default(AsyncVoid)); return tcs.Task; } private object StringToType(string stringValue) { object value = null; if (stringValue == null) value = null; else if (Descriptor.ParameterType == typeof(string)) value = stringValue; else if (Descriptor.ParameterType == typeof(int)) value = int.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(Int32)) value = Int32.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(Int64)) value = Int64.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(decimal)) value = decimal.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(double)) value = double.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(DateTime)) value = DateTime.Parse(stringValue, CultureInfo.CurrentCulture); else if (Descriptor.ParameterType == typeof(bool)) { value = false; if (stringValue == "true" || stringValue == "on" || stringValue == "1") value = true; } else value = stringValue; return value; } /// <summary> /// Read and cache the request body /// </summary> /// <param name="request"></param> /// <returns></returns> private NameValueCollection TryReadBody(HttpRequestMessage request) { object result = null; // try to read out of cache first if (!request.Properties.TryGetValue(MultipleBodyParameters, out result)) { // parsing the string like firstname=Hongmei&lastname=Ge result = request.Content.ReadAsFormDataAsync().Result; request.Properties.Add(MultipleBodyParameters, result); } return result as NameValueCollection; } private struct AsyncVoid { } } The ExecuteBindingAsync method is fired for each parameter that is mapped and sent for conversion. This custom binding is fired only if the incoming parameter is a simple type (that gets defined later when I hook up the binding), so this binding never fires on complex types or if the first type is not a simple type. For the first parameter of a request the Binding first reads the request body into a NameValueCollection and caches that in the request.Properties collection. The request body can only be read once, so the first parameter request reads it and then caches it. Subsequent parameters then use the cached POST value collection. Once the form collection is available the value of the parameter is read, and the value is translated into the target type requested by the Descriptor. SetValue writes out the value to be mapped. Once you have the ParameterBinding in place, the binding has to be assigned. This is done along with all other Web API configuration tasks at application startup in global.asax's Application_Start:GlobalConfiguration.Configuration.ParameterBindingRules .Insert(0, (HttpParameterDescriptor descriptor) => { var supportedMethods = descriptor.ActionDescriptor.SupportedHttpMethods; // Only apply this binder on POST and PUT operations if (supportedMethods.Contains(HttpMethod.Post) || supportedMethods.Contains(HttpMethod.Put)) { var supportedTypes = new Type[] { typeof(string), typeof(int), typeof(decimal), typeof(double), typeof(bool), typeof(DateTime) }; if (supportedTypes.Where(typ => typ == descriptor.ParameterType).Count() > 0) return new SimplePostVariableParameterBinding(descriptor); } // let the default bindings do their work return null; }); The ParameterBindingRules.Insert method takes a delegate that checks which type of requests it should handle. The logic here checks whether the request is POST or PUT and whether the parameter type is a simple type that is supported. Web API calls this delegate once for each method signature it tries to map and the delegate returns null to indicate it's not handling this parameter, or it returns a new parameter binding instance - in this case the SimplePostVariableParameterBinding. Once the parameter binding and this hook up code is in place, you can now pass simple POST values to methods with simple parameters. The examples I showed above should now work in addition to the standard bindings. Summary Clearly this is not easy to discover. I spent quite a bit of time digging through the Web API source trying to figure this out on my own without much luck. It took Hong Mei at Micrsoft to provide a base example as I asked around so I can't take credit for this solution :-). But once you know where to look, Web API is brilliantly extensible to make it relatively easy to customize the parameter behavior. I'm very stoked that this got resolved - in the last two months I've had two customers with projects that decided not to use Web API in AJAX heavy SPA applications because this POST variable mapping wasn't available. This might actually change their mind to still switch back and take advantage of the many great features in Web API. I too frequently use plain POST variables for communicating with server AJAX handlers and while I could have worked around this (with untyped JObject or the Form collection mostly), having proper POST to parameter mapping makes things much easier. I said this in my last post on POST data and say it again here: I think POST to method parameter mapping should have been shipped in the box with Web API, because without knowing about this limitation the expectation is that simple POST variables map to parameters just like query string values do. I hope Microsoft considers including this type of functionality natively in the next version of Web API natively or at least as a built-in HttpParameterBinding that can be just added. This is especially true, since this binding doesn't affect existing bindings. Resources SimplePostVariableParameterBinding Source on GitHub Global.asax hookup source Mapping URL Encoded Post Values in ASP.NET Web API© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api AJAX Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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Creating a JSONP Formatter for ASP.NET Web API

- by Rick Strahl

Out of the box ASP.NET WebAPI does not include a JSONP formatter, but it's actually very easy to create a custom formatter that implements this functionality. JSONP is one way to allow Browser based JavaScript client applications to bypass cross-site scripting limitations and serve data from the non-current Web server. AJAX in Web Applications uses the XmlHttp object which by default doesn't allow access to remote domains. There are number of ways around this limitation <script> tag loading and JSONP is one of the easiest and semi-official ways that you can do this. JSONP works by combining JSON data and wrapping it into a function call that is executed when the JSONP data is returned. If you use a tool like jQUery it's extremely easy to access JSONP content. Imagine that you have a URL like this: http://RemoteDomain/aspnetWebApi/albums which on an HTTP GET serves some data - in this case an array of record albums. This URL is always directly accessible from an AJAX request if the URL is on the same domain as the parent request. However, if that URL lives on a separate server it won't be easily accessible to an AJAX request. Now, if the server can serve up JSONP this data can be accessed cross domain from a browser client. Using jQuery it's really easy to retrieve the same data with JSONP:function getAlbums() { $.getJSON("http://remotedomain/aspnetWebApi/albums?callback=?",null, function (albums) { alert(albums.length); }); } The resulting callback the same as if the call was to a local server when the data is returned. jQuery deserializes the data and feeds it into the method. Here the array is received and I simply echo back the number of items returned. From here your app is ready to use the data as needed. This all works fine - as long as the server can serve the data with JSONP. What does JSONP look like? JSONP is a pretty simple 'protocol'. All it does is wrap a JSON response with a JavaScript function call. The above result from the JSONP call looks like this:Query17103401925975181569_1333408916499( [{"Id":"34043957","AlbumName":"Dirty Deeds Done Dirt Cheap",…},{…}] ) The way JSONP works is that the client (jQuery in this case) sends of the request, receives the response and evals it. The eval basically executes the function and deserializes the JSON inside of the function. It's actually a little more complex for the framework that does this, but that's the gist of what happens. JSONP works by executing the code that gets returned from the JSONP call. JSONP and ASP.NET Web API As mentioned previously, JSONP support is not natively in the box with ASP.NET Web API. But it's pretty easy to create and plug-in a custom formatter that provides this functionality. The following code is based on Christian Weyers example but has been updated to the latest Web API CodePlex bits, which changes the implementation a bit due to the way dependent objects are exposed differently in the latest builds. Here's the code: using System; using System.IO; using System.Net; using System.Net.Http.Formatting; using System.Net.Http.Headers; using System.Threading.Tasks; using System.Web; using System.Net.Http; namespace Westwind.Web.WebApi { /// <summary> /// Handles JsonP requests when requests are fired with /// text/javascript or application/json and contain /// a callback= (configurable) query string parameter /// /// Based on Christian Weyers implementation /// https://github.com/thinktecture/Thinktecture.Web.Http/blob/master/Thinktecture.Web.Http/Formatters/JsonpFormatter.cs /// </summary> public class JsonpFormatter : JsonMediaTypeFormatter { public JsonpFormatter() { SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json")); SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/javascript")); //MediaTypeMappings.Add(new UriPathExtensionMapping("jsonp", "application/json")); JsonpParameterName = "callback"; } /// <summary> /// Name of the query string parameter to look for /// the jsonp function name /// </summary> public string JsonpParameterName {get; set; } /// <summary> /// Captured name of the Jsonp function that the JSON call /// is wrapped in. Set in GetPerRequestFormatter Instance /// </summary> private string JsonpCallbackFunction; public override bool CanWriteType(Type type) { return true; } /// <summary> /// Override this method to capture the Request object /// and look for the query string parameter and /// create a new instance of this formatter. /// /// This is the only place in a formatter where the /// Request object is available. /// </summary> /// <param name="type"></param> /// <param name="request"></param> /// <param name="mediaType"></param> /// <returns></returns> public override MediaTypeFormatter GetPerRequestFormatterInstance(Type type, HttpRequestMessage request, MediaTypeHeaderValue mediaType) { var formatter = new JsonpFormatter() { JsonpCallbackFunction = GetJsonCallbackFunction(request) }; return formatter; } /// <summary> /// Override to wrap existing JSON result with the /// JSONP function call /// </summary> /// <param name="type"></param> /// <param name="value"></param> /// <param name="stream"></param> /// <param name="contentHeaders"></param> /// <param name="transportContext"></param> /// <returns></returns> public override Task WriteToStreamAsync(Type type, object value, Stream stream, HttpContentHeaders contentHeaders, TransportContext transportContext) { if (!string.IsNullOrEmpty(JsonpCallbackFunction)) { return Task.Factory.StartNew(() => { var writer = new StreamWriter(stream); writer.Write( JsonpCallbackFunction + "("); writer.Flush(); base.WriteToStreamAsync(type, value, stream, contentHeaders, transportContext).Wait(); writer.Write(")"); writer.Flush(); }); } else { return base.WriteToStreamAsync(type, value, stream, contentHeaders, transportContext); } } /// <summary> /// Retrieves the Jsonp Callback function /// from the query string /// </summary> /// <returns></returns> private string GetJsonCallbackFunction(HttpRequestMessage request) { if (request.Method != HttpMethod.Get) return null; var query = HttpUtility.ParseQueryString(request.RequestUri.Query); var queryVal = query[this.JsonpParameterName]; if (string.IsNullOrEmpty(queryVal)) return null; return queryVal; } } } Note again that this code will not work with the Beta bits of Web API - it works only with post beta bits from CodePlex and hopefully this will continue to work until RTM :-) This code is a bit different from Christians original code as the API has changed. The biggest change is that the Read/Write functions no longer receive a global context object that gives access to the Request and Response objects as the older bits did. Instead you now have to override the GetPerRequestFormatterInstance() method, which receives the Request as a parameter. You can capture the Request there, or use the request to pick up the values you need and store them on the formatter. Note that I also have to create a new instance of the formatter since I'm storing request specific state on the instance (information whether the callback= querystring is present) so I return a new instance of this formatter. Other than that the code should be straight forward: The code basically writes out the function pre- and post-amble and the defers to the base stream to retrieve the JSON to wrap the function call into. The code uses the Async APIs to write this data out (this will take some getting used to seeing all over the place for me). Hooking up the JsonpFormatter Once you've created a formatter, it has to be added to the request processing sequence by adding it to the formatter collection. Web API is configured via the static GlobalConfiguration object. protected void Application_Start(object sender, EventArgs e) { // Verb Routing RouteTable.Routes.MapHttpRoute( name: "AlbumsVerbs", routeTemplate: "albums/{title}", defaults: new { title = RouteParameter.Optional, controller = "AlbumApi" } ); GlobalConfiguration .Configuration .Formatters .Insert(0, new Westwind.Web.WebApi.JsonpFormatter()); } That's all it takes. Note that I added the formatter at the top of the list of formatters, rather than adding it to the end which is required. The JSONP formatter needs to fire before any other JSON formatter since it relies on the JSON formatter to encode the actual JSON data. If you reverse the order the JSONP output never shows up. So, in general when adding new formatters also try to be aware of the order of the formatters as they are added. Resources JsonpFormatter Code on GitHub© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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Metro: Query Selectors

- by Stephen.Walther

The goal of this blog entry is to explain how to perform queries using selectors when using the WinJS library. In particular, you learn how to use the WinJS.Utilities.query() method and the QueryCollection class to retrieve and modify the elements of an HTML document. Introduction to Selectors When you are building a Web application, you need some way of easily retrieving elements from an HTML document. For example, you might want to retrieve all of the input elements which have a certain class. Or, you might want to retrieve the one and only element with an id of favoriteColor. The standard way of retrieving elements from an HTML document is by using a selector. Anyone who has ever created a Cascading Style Sheet has already used selectors. You use selectors in Cascading Style Sheets to apply formatting rules to elements in a document. For example, the following Cascading Style Sheet rule changes the background color of every INPUT element with a class of .required in a document to the color red: input.red { background-color: red } The “input.red” part is the selector which matches all INPUT elements with a class of red. The W3C standard for selectors (technically, their recommendation) is entitled “Selectors Level 3” and the standard is located here: http://www.w3.org/TR/css3-selectors/ Selectors are not only useful for adding formatting to the elements of a document. Selectors are also useful when you need to apply behavior to the elements of a document. For example, you might want to select a particular BUTTON element with a selector and add a click handler to the element so that something happens whenever you click the button. Selectors are not specific to Cascading Style Sheets. You can use selectors in your JavaScript code to retrieve elements from an HTML document. jQuery is famous for its support for selectors. Using jQuery, you can use a selector to retrieve matching elements from a document and modify the elements. The WinJS library enables you to perform the same types of queries as jQuery using the W3C selector syntax. Performing Queries with the WinJS.Utilities.query() Method When using the WinJS library, you perform a query using a selector by using the WinJS.Utilities.query() method. The following HTML document contains a BUTTON and a DIV element: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Application1</title>  <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script>  <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> </head> <body> <button>Click Me!</button> <div style="display:none"> <h1>Secret Message</h1> </div> </body> </html> The document contains a reference to the following JavaScript file named \js\default.js: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.Utilities.query("button").listen("click", function () { WinJS.Utilities.query("div").clearStyle("display"); }); } }; app.start(); })(); The default.js script uses the WinJS.Utilities.query() method to retrieve all of the BUTTON elements in the page. The listen() method is used to wire an event handler to the BUTTON click event. When you click the BUTTON, the secret message contained in the hidden DIV element is displayed. The clearStyle() method is used to remove the display:none style attribute from the DIV element. Under the covers, the WinJS.Utilities.query() method uses the standard querySelectorAll() method. This means that you can use any selector which is compatible with the querySelectorAll() method when using the WinJS.Utilities.query() method. The querySelectorAll() method is defined in the W3C Selectors API Level 1 standard located here: http://www.w3.org/TR/selectors-api/ Unlike the querySelectorAll() method, the WinJS.Utilities.query() method returns a QueryCollection. We talk about the methods of the QueryCollection class below. Retrieving a Single Element with the WinJS.Utilities.id() Method If you want to retrieve a single element from a document, instead of matching a set of elements, then you can use the WinJS.Utilities.id() method. For example, the following line of code changes the background color of an element to the color red: WinJS.Utilities.id("message").setStyle("background-color", "red"); The statement above matches the one and only element with an Id of message. For example, the statement matches the following DIV element: <div id="message">Hello!</div> Notice that you do not use a hash when matching a single element with the WinJS.Utilities.id() method. You would need to use a hash when using the WinJS.Utilities.query() method to do the same thing like this: WinJS.Utilities.query("#message").setStyle("background-color", "red"); Under the covers, the WinJS.Utilities.id() method calls the standard document.getElementById() method. The WinJS.Utilities.id() method returns the result as a QueryCollection. If no element matches the identifier passed to WinJS.Utilities.id() then you do not get an error. Instead, you get a QueryCollection with no elements (length=0). Using the WinJS.Utilities.children() method The WinJS.Utilities.children() method enables you to retrieve a QueryCollection which contains all of the children of a DOM element. For example, imagine that you have a DIV element which contains children DIV elements like this: <div id="discussContainer"> <div>Message 1</div> <div>Message 2</div> <div>Message 3</div> </div> You can use the following code to add borders around all of the child DIV element and not the container DIV element: var discussContainer = WinJS.Utilities.id("discussContainer").get(0); WinJS.Utilities.children(discussContainer).setStyle("border", "2px dashed red"); It is important to understand that the WinJS.Utilities.children() method only works with a DOM element and not a QueryCollection. Notice that the get() method is used to retrieve the DOM element which represents the discussContainer. Working with the QueryCollection Class Both the WinJS.Utilities.query() method and the WinJS.Utilities.id() method return an instance of the QueryCollection class. The QueryCollection class derives from the base JavaScript Array class and adds several useful methods for working with HTML elements: addClass(name) – Adds a class to every element in the QueryCollection. clearStyle(name) – Removes a style from every element in the QueryCollection. conrols(ctor, options) – Enables you to create controls. get(index) – Retrieves the element from the QueryCollection at the specified index. getAttribute(name) – Retrieves the value of an attribute for the first element in the QueryCollection. hasClass(name) – Returns true if the first element in the QueryCollection has a certain class. include(items) – Includes a collection of items in the QueryCollection. listen(eventType, listener, capture) – Adds an event listener to every element in the QueryCollection. query(query) – Performs an additional query on the QueryCollection and returns a new QueryCollection. removeClass(name) – Removes a class from the every element in the QueryCollection. removeEventListener(eventType, listener, capture) – Removes an event listener from every element in the QueryCollection. setAttribute(name, value) – Adds an attribute to every element in the QueryCollection. setStyle(name, value) – Adds a style attribute to every element in the QueryCollection. template(templateElement, data, renderDonePromiseContract) – Renders a template using the supplied data. toggleClass(name) – Toggles the specified class for every element in the QueryCollection. Because the QueryCollection class derives from the base Array class, it also contains all of the standard Array methods like forEach() and slice(). Summary In this blog post, I’ve described how you can perform queries using selectors within a Windows Metro Style application written with JavaScript. You learned how to return an instance of the QueryCollection class by using the WinJS.Utilities.query(), WinJS.Utilities.id(), and WinJS.Utilities.children() methods. You also learned about the methods of the QueryCollection class.

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CodePlex Daily Summary for Monday, June 10, 2013

CodePlex Daily Summary for Monday, June 10, 2013Popular ReleasesNexusCamera: NexusCamera: Nexus Camera is a control for Windows Phone 7 & 8, which can be used as a menu on the Camera. The idea in making this control when we use a camera nexus. Thanks for Nexus. Need Windows Phone Toolkit https://phone.codeplex.com/ View Sample Camera http://tctechcrunch2011.files.wordpress.com/2012/11/nexus4-camera.jpgVR Player: VR Player 0.3 ALPHA: New plugin system with individual folders TrackIR support Maya and 3ds max formats support Dual screen support Mono layouts (left and right) Cylinder height parameter Barel effect factor parameter Razer hydra filter parameter VRPN bug fixes UI improvements Performances improvements Stabilization and logging with Log4Net New default values base on users feedback CTRL key to open menuZXMAK2: Version 2.7.5.4: - add hayes modem device (thanks to Eltaron) - add host joystick selection - fix joystick bits (swapped in previous version)SimCityPak: SimCityPak 0.1.0.8: SimCityPak 0.1.0.8 New features: Import BMP color palettes for vehicles Import RASTER file (uncompressed 8.8.8.8 DDS files) View different channels of RASTER files or preview of all layers combined Find text in javascripts TGA viewer Ground textures added to lot editor Many additional identified instances and propertiesWsus Package Publisher: Release v1.2.1306.09: Add more verifications on certificate validation. WPP will not let user to try publishing an update until the certificate is valid. Add certificate expiration date on the 'About' form. Filter Approbation to avoid a user to try to approve an update for uninstallation when the update do not support uninstallation. Add the server and console version on the 'About' form. WPP will not let user to publish an update until the server and console are not at the same level. WPP do not let user ...AJAX Control Toolkit: June 2013 Release: AJAX Control Toolkit Release Notes - June 2013 Release Version 7.0607June 2013 release of the AJAX Control Toolkit. AJAX Control Toolkit .NET 4.5 – AJAX Control Toolkit for .NET 4.5 and sample site (Recommended). AJAX Control Toolkit .NET 4 – AJAX Control Toolkit for .NET 4 and sample site (Recommended). AJAX Control Toolkit .NET 3.5 – AJAX Control Toolkit for .NET 3.5 and sample site (Recommended). Notes: - Instructions for using the AJAX Control Toolkit with ASP.NET 4.5 can be found at...Rawr: Rawr 5.2.1: This is the Downloadable WPF version of Rawr!For web-based version see http://elitistjerks.com/rawr.php You can find the version notes at: http://rawr.codeplex.com/wikipage?title=VersionNotes Rawr Addon (NOT UPDATED YET FOR MOP)We now have a Rawr Official Addon for in-game exporting and importing of character data hosted on Curse. The Addon does not perform calculations like Rawr, it simply shows your exported Rawr data in wow tooltips and lets you export your character to Rawr (including ba...VG-Ripper & PG-Ripper: PG-Ripper 1.4.13: changes NEW: Added Support for "ImageJumbo.com" links FIXED: Ripping of Threads with multiple pagesXomega Framework: Xomega.Framework 1.4: Adding support for Visual Studio 2012 and .Net framework 4.5. Minor bug fixes and enhancements.sb0t v.5: sb0t 5.14: Stability fix in script engine. Avatar.exists property fixed in scripting. cb0t custom font protocol re-added and updated to support new Ares.ASP.NET MVC Forum: MVCForum v1.3.5: This is a bug release version, with a couple of small usability features and UI changes. All the small amount of bugs reported in v1.3 have been fixed, no upgrade needed just overwrite the files and everything should just work.Json.NET: Json.NET 5.0 Release 6: New feature - Added serialized/deserialized JSON to verbose tracing New feature - Added support for using type name handling with ISerializable content Fix - Fixed not using default serializer settings with primitive values and JToken.ToObject Fix - Fixed error writing BigIntegers with JsonWriter.WriteToken Fix - Fixed serializing and deserializing flag enums with EnumMember attribute Fix - Fixed error deserializing interfaces with a valid type converter Fix - Fixed error deser...Christoc's DotNetNuke Module Development Template: DotNetNuke 7 Project Templates V2.3 for VS2012: V2.3 - Release Date 6/5/2013 Items addressed in this 2.3 release Fixed bad namespace for BusinessController in one of the C# templates. Updated documentation in all templates. Setting up your DotNetNuke Module Development Environment Installing Christoc's DotNetNuke Module Development Templates Customizing the latest DotNetNuke Module Development Project TemplatesPulse: Pulse 0.6.7.0: A number of small bug fixes to stabilize the previous Beta. Sorry about the never ending "New Version" bug!QlikView Extension - Animated Scatter Chart: Animated Scatter Chart - v1.0: Version 1.0 including Source Code qar File Example QlikView application Tested With: Browser Firefox 20 (x64) Google Chrome 27 (x64) Internet Explorer 9 QlikView QlikView Desktop 11 - SR2 (x64) QlikView Desktop 11.2 - SR1 (x64) QlikView Ajax Client 11.2 - SR2 (based on x64)BarbaTunnel: BarbaTunnel 7.2: Warning: HTTP Tunnel is not compatible with version 6.x and prior, HTTP packet format has been changed. Check Version History for more information about this release.SuperWebSocket, a .NET WebSocket Server: SuperWebSocket 0.8: This release includes these changes below: Upgrade SuperSocket to 1.5.3 which is much more stable Added handshake request validating api (WebSocketServer.ValidateHandshake(TWebSocketSession session, string origin)) Fixed a bug that the m_Filters in the SubCommandBase can be null if the command's method LoadSubCommandFilters(IEnumerable<SubCommandFilterAttribute> globalFilters) is not invoked Fixed the compatibility issue on Origin getting in the different version protocols Marked ISub...BlackJumboDog: Ver5.9.0: 2013.06.04 Ver5.9.0 (1) ?????????????????????????????????($Remote.ini Tmp.ini) (2) ThreadBaseTest?? (3) ????POP3??????SMTP???????????????? (4) Web???????、?????????URL??????????????? (5) Ftp???????、LIST?????????????? (6) ?????????????????????Media Companion: Media Companion MC3.569b: New* Movies - Autoscrape/Batch Rescrape extra fanart and or extra thumbs. * Movies - Alternative editor can add manually actors. * TV - Batch Rescraper, AutoScrape extrafanart, if option enabled. Fixed* Movies - Slow performance switching to movie tab by adding option 'Disable "Not Matching Rename Pattern"' to Movie Preferences - General. * Movies - Fixed only actors with images were scraped and added to nfo * Movies - Fixed filter reset if selected tab was above Home Movies. * Updated Medi...Nearforums - ASP.NET MVC forum engine: Nearforums v9.0: Version 9.0 of Nearforums with great new features for users and developers: SQL Azure support Admin UI for Forum Categories Avoid html validation for certain roles Improve profile picture moderation and support Warn, suspend, and ban users Web administration of site settings Extensions support Visit the Roadmap for more details. Webdeploy package sha1 checksum: 9.0.0.0: e687ee0438cd2b1df1d3e95ecb9d66e7c538293b New ProjectsASP.NET MVC 4 and RequireJS: ASP.NET MVC 4 application with Areas and RequireJSBaseX - Base converter and calculator: Dealing with numbers of any base in .NET.C# Exercises: C# ExercisesClassfinder: ClassfinderCreative OS ALPHA: This is a OS!!!!CSS Exercises: CSS ExercisesCustom Workflow Action: Project showing how to create and use Custom Workflow Action for SharePoint Designer 2013.Devshed Tools: Provides easy to use and compile-time-support solution for various type of projects on the .NET framework. Currently Devshed.Web is in development.Envar Editor: Edit environment variables easily on windowsExcel To Sql: A simplified tool for importing Excel data into SQL.HTML Exercises: HTML ExercisesKnockout.js with ASP.NET MVC: This project implements a system which maps .NET ViewModels to javascript ViewModels for use with knockout.js, using Razor markup syntax.LogoBids: LOGO??????,ORM??OpenAccess ORMManagistics: Management Logistics Application (including: Warehouse, Sale, Purchase, ...)Matrix Switch Preset Utility: A small utility for managing the inputs and outputs from a matrix switch via RS-232. Developed in WPF (VB9) and running on the .Net3.5SP1 framework.MvcSystemsCommander: An ASP.NET C# MVC4 webapp to help systems administrators consolidate common systems administration tasksNewspaperAgent: My small projectOutlook Recovery Software - Efficiently Repair Damaged PST File: This project tells you the easiest way to recover PST file of Outlook. Complete information has been given here to help users.Pattern: Testprocedure: a new procedural programming framework based on .net, by using lambda expression, it can handle async io friendly and provide a full lock-free solutionSharePoint 2013 custom field samples: SharePoint 2013 custom field samples is a research project aims to provide samples for developing custom fields in SharePoint 2013.SharePoint 2013 List Forms: This small framework allows you to manage custom list forms using rendering templates and controls stored in a SharePoint library.The Coconut Cranium Decision Engine: The Coconut Cranium Decision Engine is a boolean decision engine using the most mind-bendingly worse way of working.TxtToSeq: Command line utility to convert Commodore SEQ files to TXT files and vice-versa.ultgw: ult gw

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Unity – Part 5: Injecting Values

- by Ricardo Peres

Introduction This is the fifth post on Unity. You can find the introductory post here, the second post, on dependency injection here, a third one on Aspect Oriented Programming (AOP) here and the latest so far, on writing custom extensions, here. This time we will talk about injecting simple values. An Inversion of Control (IoC) / Dependency Injector (DI) container like Unity can be used for things other than injecting complex class dependencies. It can also be used for setting property values or method/constructor parameters whenever a class is built. The main difference is that these values do not have a lifetime manager associated with them and do not come from the regular IoC registration store. Unlike, for instance, MEF, Unity won’t let you register as a dependency a string or an integer, so you have to take a different approach, which I will describe in this post. Scenario Let’s imagine we have a base interface that describes a logger – the same as in previous examples: 1: public interface ILogger 2: { 3: void Log(String message); 4: } And a concrete implementation that writes to a file: 1: public class FileLogger : ILogger 2: { 3: public String Filename 4: { 5: get; 6: set; 7: } 8: 9: #region ILogger Members 10: 11: public void Log(String message) 12: { 13: using (Stream file = File.OpenWrite(this.Filename)) 14: { 15: Byte[] data = Encoding.Default.GetBytes(message); 16: 17: file.Write(data, 0, data.Length); 18: } 19: } 20: 21: #endregion 22: } And let’s say we want the Filename property to come from the application settings (appSettings) section on the Web/App.config file. As usual with Unity, there is an extensibility point that allows us to automatically do this, both with code configuration or statically on the configuration file. Extending Injection We start by implementing a class that will retrieve a value from the appSettings by inheriting from ValueElement: 1: sealed class AppSettingsParameterValueElement : ValueElement, IDependencyResolverPolicy 2: { 3: #region Private methods 4: private Object CreateInstance(Type parameterType) 5: { 6: Object configurationValue = ConfigurationManager.AppSettings[this.AppSettingsKey]; 7: 8: if (parameterType != typeof(String)) 9: { 10: TypeConverter typeConverter = this.GetTypeConverter(parameterType); 11: 12: configurationValue = typeConverter.ConvertFromInvariantString(configurationValue as String); 13: } 14: 15: return (configurationValue); 16: } 17: #endregion 18: 19: #region Private methods 20: private TypeConverter GetTypeConverter(Type parameterType) 21: { 22: if (String.IsNullOrEmpty(this.TypeConverterTypeName) == false) 23: { 24: return (Activator.CreateInstance(TypeResolver.ResolveType(this.TypeConverterTypeName)) as TypeConverter); 25: } 26: else 27: { 28: return (TypeDescriptor.GetConverter(parameterType)); 29: } 30: } 31: #endregion 32: 33: #region Public override methods 34: public override InjectionParameterValue GetInjectionParameterValue(IUnityContainer container, Type parameterType) 35: { 36: Object value = this.CreateInstance(parameterType); 37: return (new InjectionParameter(parameterType, value)); 38: } 39: #endregion 40: 41: #region IDependencyResolverPolicy Members 42: 43: public Object Resolve(IBuilderContext context) 44: { 45: Type parameterType = null; 46: 47: if (context.CurrentOperation is ResolvingPropertyValueOperation) 48: { 49: ResolvingPropertyValueOperation op = (context.CurrentOperation as ResolvingPropertyValueOperation); 50: PropertyInfo prop = op.TypeBeingConstructed.GetProperty(op.PropertyName); 51: parameterType = prop.PropertyType; 52: } 53: else if (context.CurrentOperation is ConstructorArgumentResolveOperation) 54: { 55: ConstructorArgumentResolveOperation op = (context.CurrentOperation as ConstructorArgumentResolveOperation); 56: String args = op.ConstructorSignature.Split('(')[1].Split(')')[0]; 57: Type[] types = args.Split(',').Select(a => Type.GetType(a.Split(' ')[0])).ToArray(); 58: ConstructorInfo ctor = op.TypeBeingConstructed.GetConstructor(types); 59: parameterType = ctor.GetParameters().Where(p => p.Name == op.ParameterName).Single().ParameterType; 60: } 61: else if (context.CurrentOperation is MethodArgumentResolveOperation) 62: { 63: MethodArgumentResolveOperation op = (context.CurrentOperation as MethodArgumentResolveOperation); 64: String methodName = op.MethodSignature.Split('(')[0].Split(' ')[1]; 65: String args = op.MethodSignature.Split('(')[1].Split(')')[0]; 66: Type[] types = args.Split(',').Select(a => Type.GetType(a.Split(' ')[0])).ToArray(); 67: MethodInfo method = op.TypeBeingConstructed.GetMethod(methodName, types); 68: parameterType = method.GetParameters().Where(p => p.Name == op.ParameterName).Single().ParameterType; 69: } 70: 71: return (this.CreateInstance(parameterType)); 72: } 73: 74: #endregion 75: 76: #region Public properties 77: [ConfigurationProperty("appSettingsKey", IsRequired = true)] 78: public String AppSettingsKey 79: { 80: get 81: { 82: return ((String)base["appSettingsKey"]); 83: } 84: 85: set 86: { 87: base["appSettingsKey"] = value; 88: } 89: } 90: #endregion 91: } As you can see from the implementation of the IDependencyResolverPolicy.Resolve method, this will work in three different scenarios: When it is applied to a property; When it is applied to a constructor parameter; When it is applied to an initialization method. The implementation will even try to convert the value to its declared destination, for example, if the destination property is an Int32, it will try to convert the appSettings stored string to an Int32. Injection By Configuration If we want to configure injection by configuration, we need to implement a custom section extension by inheriting from SectionExtension, and registering our custom element with the name “appSettings”: 1: sealed class AppSettingsParameterInjectionElementExtension : SectionExtension 2: { 3: public override void AddExtensions(SectionExtensionContext context) 4: { 5: context.AddElement<AppSettingsParameterValueElement>("appSettings"); 6: } 7: } And on the configuration file, for setting a property, we use it like this: 1: <appSettings> 2: <add key="LoggerFilename" value="Log.txt"/> 3: </appSettings> 4: <unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> 5: <container> 6: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.ConsoleLogger, MyAssembly"/> 7: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.FileLogger, MyAssembly" name="File"> 8: <lifetime type="singleton"/> 9: <property name="Filename"> 10: <appSettings appSettingsKey="LoggerFilename"/> 11: </property> 12: </register> 13: </container> 14: </unity> If we would like to inject the value as a constructor parameter, it would be instead: 1: <unity xmlns="http://schemas.microsoft.com/practices/2010/unity"> 2: <sectionExtension type="MyNamespace.AppSettingsParameterInjectionElementExtension, MyAssembly" /> 3: <container> 4: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.ConsoleLogger, MyAssembly"/> 5: <register type="MyNamespace.ILogger, MyAssembly" mapTo="MyNamespace.FileLogger, MyAssembly" name="File"> 6: <lifetime type="singleton"/> 7: <constructor> 8: <param name="filename" type="System.String"> 9: <appSettings appSettingsKey="LoggerFilename"/> 10: </param> 11: </constructor> 12: </register> 13: </container> 14: </unity> Notice the appSettings section, where we add a LoggerFilename entry, which is the same as the one referred by our AppSettingsParameterInjectionElementExtension extension. For more advanced behavior, you can add a TypeConverterName attribute to the appSettings declaration, where you can pass an assembly qualified name of a class that inherits from TypeConverter. This class will be responsible for converting the appSettings value to a destination type. Injection By Attribute If we would like to use attributes instead, we need to create a custom attribute by inheriting from DependencyResolutionAttribute: 1: [Serializable] 2: [AttributeUsage(AttributeTargets.Parameter | AttributeTargets.Property, AllowMultiple = false, Inherited = true)] 3: public sealed class AppSettingsDependencyResolutionAttribute : DependencyResolutionAttribute 4: { 5: public AppSettingsDependencyResolutionAttribute(String appSettingsKey) 6: { 7: this.AppSettingsKey = appSettingsKey; 8: } 9: 10: public String TypeConverterTypeName 11: { 12: get; 13: set; 14: } 15: 16: public String AppSettingsKey 17: { 18: get; 19: private set; 20: } 21: 22: public override IDependencyResolverPolicy CreateResolver(Type typeToResolve) 23: { 24: return (new AppSettingsParameterValueElement() { AppSettingsKey = this.AppSettingsKey, TypeConverterTypeName = this.TypeConverterTypeName }); 25: } 26: } As for file configuration, there is a mandatory property for setting the appSettings key and an optional TypeConverterName for setting the name of a TypeConverter. Both the custom attribute and the custom section return an instance of the injector AppSettingsParameterValueElement that we implemented in the first place. Now, the attribute needs to be placed before the injected class’ Filename property: 1: public class FileLogger : ILogger 2: { 3: [AppSettingsDependencyResolution("LoggerFilename")] 4: public String Filename 5: { 6: get; 7: set; 8: } 9: 10: #region ILogger Members 11: 12: public void Log(String message) 13: { 14: using (Stream file = File.OpenWrite(this.Filename)) 15: { 16: Byte[] data = Encoding.Default.GetBytes(message); 17: 18: file.Write(data, 0, data.Length); 19: } 20: } 21: 22: #endregion 23: } Or, if we wanted to use constructor injection: 1: public class FileLogger : ILogger 2: { 3: public String Filename 4: { 5: get; 6: set; 7: } 8: 9: public FileLogger([AppSettingsDependencyResolution("LoggerFilename")] String filename) 10: { 11: this.Filename = filename; 12: } 13: 14: #region ILogger Members 15: 16: public void Log(String message) 17: { 18: using (Stream file = File.OpenWrite(this.Filename)) 19: { 20: Byte[] data = Encoding.Default.GetBytes(message); 21: 22: file.Write(data, 0, data.Length); 23: } 24: } 25: 26: #endregion 27: } Usage Just do: 1: ILogger logger = ServiceLocator.Current.GetInstance<ILogger>("File"); And off you go! A simple way do avoid hardcoded values in component registrations. Of course, this same concept can be applied to registry keys, environment values, XML attributes, etc, etc, just change the implementation of the AppSettingsParameterValueElement class. Next stop: custom lifetime managers.

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