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• Drools flow architecture, Drools flow events with AND join nodes

  - by Shoukry K

  I have been evaluating a number of frameworks including jBPM and Drools flow for my application requirements. Lots of the opinions seem to be inclined towards Drools flow as its more flexible, knowledge oriented, easier to integrate with business rules, etc.. The application is some sort of an Email Campaign manager , where different customers can sign in, prepare (design) and launch email campaigns. The application should be able to do the following : 1- Receive a list of email addresses, send emails to each of these addresses starting from a certain date and during a certain time interval of the day , do some custom actions, and then wait for reply emails. 2- If a reply email is received and depending on the response text of the email , and depending on the time the email was received certain actions need to happen, web service calls need to take place, and error handling for these calls. 3- The application will manage and run many and different campaigns (different customers and different flows for each customer) at any point of time. The first question is : Is Drools flow the way to go about this? My main concerns are scalability, suspending, resuming flows, and long wait, and flows management. As you see from the requirements : There is a scheduling part : Certain flows need to be run at a certain point in time, they need to get suspended and then resumed. For example start sending emails starting on Dec 1st 2010 and send emails only in the time interval between 08:00 and 17:00 GMT. By then it might be that all subscribers have been sent emails, but it might not be the case, the process needs to (resume) on Dec 2nd and send a second batch, however certain (users) already received emails and they should be able to (continue at different stages of the flow) There are long wait states : Days or even weeks , i need to persist, suspend / resume and terminate flows (manage flows) External Events : This is where i got stuck first, i tried to put together a simple flow (see attached screenshot) See image http://img46.imageshack.us/img46/9620/workflowwithevents.png , there is a start node , connected to an action node, connected to a join. An event node is connected to a second action node, which is connected to the join. The join is an AND join , after the join there is an action and the end node. Here is the sample code i am using to launch the flow : KnowledgeBuilder builder = KnowledgeBuilderFactory .newKnowledgeBuilder(); builder.add(ResourceFactory.newClassPathResource("campaign.rf", CampaignsDroolsPoc.class), ResourceType.DRF); if (builder.hasErrors()) { KnowledgeBuilderErrors errors = builder.getErrors(); Iterator<KnowledgeBuilderError> iterator = errors.iterator(); while (iterator.hasNext()) { System.out.println(iterator.next().toString()); } } KnowledgeBase base = KnowledgeBaseFactory.newKnowledgeBase(); base.addKnowledgePackages(builder.getKnowledgePackages()); final StatefulKnowledgeSession ksession = base .newStatefulKnowledgeSession(); // KnowledgeRuntimeLoggerFactory.newConsoleLogger(ksession); ksession.getWorkItemManager().registerWorkItemHandler("Log", new SendSMSWorkItemHandler()); ProcessInstance startProcess = ksession.startProcess("flow"); System.out.println("Signaling event"); startProcess.signalEvent("ev1", "ev1"); System.out.println("Signaled"); ksession.fireUntilHalt(); I am noticing that the event get triggered, the action node connected to the event gets triggered, however things seem to get stuck at the join. The flow does not continue past the AND join and the flow seems to get stuck. The action following the node does not get triggered. I also went through the drools flow documentation , and all the example codes, however i didn't find anything there. In addition any hints about the way to go about architecting the solution, and implementing it would be great.

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• Why does async BeginReceiveFrom never time out on a raw socket?

  - by James Hugard

  Writing an asynchronous Ping using Raw Sockets in F#, to enable parallel requests using as few threads as possible. Not using "System.Net.NetworkInformation.Ping", because it appears to allocate one thread per request. Am also 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. Not sure if this is a .NET issue, or an F# one... Any ideas? (note: the process must run as Admin to allow Raw Socket access) This throws a timeout: let result = Ping.Ping ( IPAddress.Parse( "192.168.33.22" ), 1000 ) However, this hangs: let result = Ping.AsyncPing ( 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 AsyncPing (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 detect a timeout when using asynchronous Socket.BeginReceive?

  - by James Hugard

  Writing an asynchronous Ping using Raw Sockets in F#, to enable parallel requests using as few threads as possible. Not using "System.Net.NetworkInformation.Ping", because it appears to allocate one thread per request. Am also 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. Not sure if this is a .NET issue, or an F# one... Any ideas? (note: the process must run as Admin to allow Raw Socket access) This throws a timeout: let result = Ping.Ping ( IPAddress.Parse( "192.168.33.22" ), 1000 ) However, this hangs: let result = Ping.AsyncPing ( 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 AsyncPing (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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• Problem Registering a Generic Repository with Windsor IoC

  - by Robin

  I’m fairly new to IoC and perhaps my understanding of generics and inheritance is not strong enough for what I’m trying to do. You might find this to be a mess. I have a generic Repository base class: public class Repository<TEntity> where TEntity : class, IEntity { private Table<TEntity> EntityTable; private string _connectionString; private string _userName; public string UserName { get { return _userName; } set { _userName = value; } } public Repository() {} public Repository(string connectionString) { _connectionString = connectionString; EntityTable = (new DataContext(connectionString)).GetTable<TEntity>(); } public Repository(string connectionString, string userName) { _connectionString = connectionString; _userName = userName; EntityTable = (new DataContext(connectionString)).GetTable<TEntity>(); } // Data access methods ... ... } and a SqlClientRepository that inherits Repository: public class SqlClientRepository : Repository<Client> { private Table<Client> ClientTable; private string _connectionString; private string _userName; public SqlClientRepository() {} public SqlClientRepository(string connectionString) : base(connectionString) { _connectionString = connectionString; ClientTable = (new DataContext(connectionString)).GetTable<Client>(); } public SqlClientRepository(string connectionString, string userName) : base(connectionString, userName) { _connectionString = connectionString; _userName = userName; ClientTable = (new DataContext(connectionString)).GetTable<Client>(); } // data access methods unique to Client repository ... } The Repository class provides some generics methods like Save, Delete, etc, that I want all my repository derived classes to share. The TEntity parameter is constrained to the IEntity interface: public interface IEntity { int Id { get; set; } NameValueCollection GetSaveRuleViolations(); NameValueCollection GetDeleteRuleViolations(); } This allows the Repository class to reference these methods within its Save and Delete methods. Unit tests work fine on mock SqlClientRepository instances as well as live unit tests on the real database. However, in the MVC context: public class ClientController : Controller { private SqlClientRepository _clientRepository; public ClientController(SqlClientRepository clientRepository) { this._clientRepository = clientRepository; } public ClientController() { } // ViewResult methods ... ... } ... _clientRepository is always null. I’m using Windor Castle as an IoC container. Here is the configuration: <component id="ClientRepository" service="DomainModel.Concrete.Repository`1[[DomainModel.Entities.Client, DomainModel]], DomainModel" type="DomainModel.Concrete.SqlClientRepository, DomainModel" lifestyle="PerWebRequest"> <parameters> <connectionString>#{myConnStr}</connectionString> </parameters> </component> I’ve tried many variations in the Windsor configuration file. I suspect it’s more of a design flaw in the above code. As I'm looking over my code, it occurs to me that when registering components with an IoC container, perhaps service must always be an interface. Could this be it? Does anybody have a suggestion? Thanks in advance.

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• How to Access a descendant object's internal method in C#

  - by Giovanni Galbo

  I'm trying to access a method that is marked as internal in the parent class (in its own assembly) in an object that inherits from the same parent. Let me explain what I'm trying to do... I want to create Service classes that return IEnumberable with an underlying List to non-Service classes (e.g. the UI) and optionally return an IEnumerable with an underlying IQueryable to other services. I wrote some sample code to demonstrate what I'm trying to accomplish, shown below. The example is not real life, so please remember that when commenting. All services would inherit from something like this (only relevant code shown): public class ServiceBase<T> { protected readonly ObjectContext _context; protected string _setName = String.Empty; public ServiceBase(ObjectContext context) { _context = context; } public IEnumerable<T> GetAll() { return GetAll(false); } //These are not the correct access modifiers.. I want something //that is accessible to children classes AND between descendant classes internal protected IEnumerable<T> GetAll(bool returnQueryable) { var query = _context.CreateQuery<T>(GetSetName()); if(returnQueryable) { return query; } else { return query.ToList(); } } private string GetSetName() { //Some code... return _setName; } } Inherited services would look like this: public class EmployeeService : ServiceBase<Employees> { public EmployeeService(ObjectContext context) : base(context) { } } public class DepartmentService : ServiceBase<Departments> { private readonly EmployeeService _employeeService; public DepartmentService(ObjectContext context, EmployeeService employeeService) : base(context) { _employeeService = employeeService; } public IList<Departments> DoSomethingWithEmployees(string lastName) { //won't work because method with this signature is not visible to this class var emps = _employeeService.GetAll(true); //more code... } } Because the parent class lives is reusable, it would live in a different assembly than the child services. With GetAll(bool returnQueryable) being marked internal, the children would not be able to see each other's GetAll(bool) method, just the public GetAll() method. I know that I can add a new internal GetAll method to each service (or perhaps an intermediary parent class within the same assembly) so that each child service within the assembly can see each other's method; but it seems unnecessary since the functionality is already available in the parent class. For example: internal IEnumerable<Employees> GetAll(bool returnIQueryable) { return base.GetAll(returnIQueryable); } Essentially what I want is for services to be able to access other service methods as IQueryable so that they can further refine the uncommitted results, while everyone else gets plain old lists. Any ideas? EDIT You know what, I had some fun playing a little code golf with this... but ultimately I wouldn't be able to use this scheme anyway because I pass interfaces around, not classes. So in my example GetAll(bool returnIQueryable) would not be in the interface, meaning I'd have to do casting, which goes against what I'm trying to accomplish. I'm not sure if I had a brain fart or if I was just too excited trying to get something that I thought was neat to work. Either way, thanks for the responses.

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• Simple Observation in Django: How Can I Correctly Modify The `attrs` sent to __new__ of a Django Mod

  - by DGGenuine

  Hello, I'm a strong proponent of the observer pattern, and this is what I'd like to be able to do in my Django models.py: class AModel(Model): __metaclass__ = SomethingMagical @post_save(AnotherModel) @classmethod def observe_another_model_saved(klass, sender, instance, created, **kwargs): pass @pre_init('YetAnotherModel') @classmethod def observe_yet_another_model_initializing(klass, sender, *args, **kwargs): pass @post_delete('DifferentApp.SomeModel') @classmethod def observe_some_model_deleted(klass, sender, **kwargs): pass This would connect a signal with sender = the decorator's argument and receiver = the decorated method. Right now my signal connection code all exists in __init__.py which is okay, but a little unmaintainable. I want this code all in one place, the models.py file. Thanks to helpful feedback from the community I'm very close (I think.) (I'm using a metaclass solution instead of the class decorator solution in the previous question/answer because you can't set attributes on classmethods, which I need.) I am having a strange error I don't understand. At the end of my post are the contents of a models.py that you can pop into a fresh project/application to see the error. Set your database to sqlite and add the application to installed apps. This is the error: Validating models... Unhandled exception in thread started by Traceback (most recent call last): File "/Library/Python/2.6/site-packages//lib/python2.6/site-packages/django/core/management/commands/runserver.py", line 48, in inner_run File "/Library/Python/2.6/site-packages/django/core/management/base.py", line 253, in validate raise CommandError("One or more models did not validate:\n%s" % error_text) django.core.management.base.CommandError: One or more models did not validate: local.myothermodel: 'my_model' has a relation with model MyModel, which has either not been installed or is abstract. I've indicated a few different things you can comment in/out to fix the error. First, if you don't modify the attrs sent to the metaclass's __new__, then the error does not arise. (Note even if you copy the dictionary element by element into a new dictionary, it still fails; only using the exact attrs dictionary works.) Second, if you reference the first model by class rather than by string, the error also doesn't arise regardless of what you do in __new__. I appreciate your help. I'll be githubbing the solution if and when it works. Maybe other people would enjoy a simplified way to use Django signals to observe application happenings. #models.py from django.db import models from django.db.models.base import ModelBase from django.db.models import signals import pdb class UnconnectedMethodWrapper(object): sender = None method = None signal = None def __init__(self, signal, sender, method): self.signal = signal self.sender = sender self.method = method def post_save(sender): return _make_decorator(signals.post_save, sender) def _make_decorator(signal, sender): def decorator(view): return UnconnectedMethodWrapper(signal, sender, view) return decorator class ConnectableModel(ModelBase): """ A meta class for any class that will have static or class methods that need to be connected to signals. """ def __new__(cls, name, bases, attrs): unconnecteds = {} ## NO WORK newattrs = {} for name, attr in attrs.iteritems(): if isinstance(attr, UnconnectedMethodWrapper): unconnecteds[name] = attr newattrs[name] = attr.method #replace the UnconnectedMethodWrapper with the method it wrapped. else: newattrs[name] = attr ## NO WORK # newattrs = {} # for name, attr in attrs.iteritems(): # newattrs[name] = attr ## WORKS # newattrs = attrs new = super(ConnectableModel, cls).__new__(cls, name, bases, newattrs) for name, unconnected in unconnecteds.iteritems(): _connect_signal(unconnected.signal, unconnected.sender, getattr(new, name), new._meta.app_label) return new def _connect_signal(signal, sender, receiver, default_app_label): # full implementation also accepts basestring as sender and will look up model accordingly signal.connect(sender=sender, receiver=receiver) class MyModel(models.Model): __metaclass__ = ConnectableModel @post_save('In my application this string matters') @classmethod def observe_it(klass, sender, instance, created, **kwargs): pass @classmethod def normal_class_method(klass): pass class MyOtherModel(models.Model): ## WORKS # my_model = models.ForeignKey(MyModel) ## NO WORK my_model = models.ForeignKey('MyModel')

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• Marking multi-level nested forms as "dirty" in Rails

  - by Charles Kihe

  I have a three-level multi-nested form in Rails. The setup is like this: Projects have many Milestones, and Milestones have many Notes. The goal is to have everything editable within the page with JavaScript, where we can add multiple new Milestones to a Project within the page, and add new Notes to new and existing Milestones. Everything works as expected, except that when I add new notes to an existing Milestone (new Milestones work fine when adding notes to them), the new notes won't save unless I edit any of the fields that actually belong to the Milestone to mark the form "dirty"/edited. Is there a way to flag the Milestone so that the new Notes that have been added will save? Edit: sorry, it's hard to paste in all of the code because there's so many parts, but here goes: Models class Project < ActiveRecord::Base has_many :notes, :dependent => :destroy has_many :milestones, :dependent => :destroy accepts_nested_attributes_for :milestones, :allow_destroy => true accepts_nested_attributes_for :notes, :allow_destroy => true, :reject_if => proc { |attributes| attributes['content'].blank? } end class Milestone < ActiveRecord::Base belongs_to :project has_many :notes, :dependent => :destroy accepts_nested_attributes_for :notes, :allow_destroy => true, :allow_destroy => true, :reject_if => proc { |attributes| attributes['content'].blank? } end class Note < ActiveRecord::Base belongs_to :milestone belongs_to :project scope :newest, lambda { |*args| order('created_at DESC').limit(*args.first || 3) } end I'm using an jQuery-based, unobtrusive version of Ryan Bates' combo helper/JS code to get this done. Application Helper def add_fields_for_association(f, association, partial) new_object = f.object.class.reflect_on_association(association).klass.new fields = f.fields_for(association, new_object, :child_index => "new_#{association}") do |builder| render(partial, :f => builder) end end I render the form for the association in a hidden div, and then use the following JavaScript to find it and add it as needed. JavaScript function addFields(link, association, content, func) { var newID = new Date().getTime(); var regexp = new RegExp("new_" + association, "g"); var form = content.replace(regexp, newID); var link = $(link).parent().next().before(form).prev(); if (func) { func.call(); } return link; } I'm guessing the only other relevant piece of code that I can think of would be the create method in the NotesController: def create respond_with(@note = @owner.notes.create(params[:note])) do |format| format.js { render :json => @owner.notes.newest(3).all.to_json } format.html { redirect_to((@milestone ? [@project, @milestone, @note] : [@project, @note]), :notice => 'Note was successfully created.') } end end The @owner ivar is created in the following before filter: def load_milestone @milestone = @project.milestones.find(params[:milestone_id]) if params[:milestone_id] end def determine_owner @owner = load_milestone @owner ||= @project end Thing is, all this seems to work fine, except when I'm adding new notes to existing milestones. The milestone has to be "touched" in order for new notes to save, or else Rails won't pay attention.

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• XSD Schema for XML with multiple structures

  - by Xetius

  I am attempting to write an XML Schema to cover a number of XML conditions which I may encounter. I have the same root element (serviceRequest) with different child elements. I was trying to use the xs:extension element to define multiple versions, but it is complaining about unexpected element orderInclusionCriteria etc. Am I going about this the right way, or is there a better way to define this? The other way I thought about this was to have a single xs:choice with all the options inside it, but this seemed somewhat inelegant. These XSD files are for use within XMLBeans if that makes any difference. I have Given the following 2 examples of XML: 1) <?xml version="1.0" encoding="utf-8"?> <serviceRequest method="GOO" debug="NO"> <sessionId sID="ABC1234567" /> <orderInclusionCriteria accountId="1234567" accountNum="1234567890" /> </serviceRequest> 2) <?xml version="1.0" encoding="utf-8"?> <serviceRequest method="GOO" debug="NO"> <sessionId sID="ABC1234567" /> <action aType='MakePayment'> <makePayment accountID='CH91015165S' amount='5.00' /> </action> </serviceRequest> I thought I could use the following schema file: <?xml version="1.0" encoding="UTF-8"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="serviceRequest" type="ServiceRequestType" /> <xs:element name="session" type="SessionType" /> <xs:attribute name="method" type="xs:string" /> <xs:attribute name="debug" type="xs:string" /> <xs:complexType name="SessionType"> <xs:attribute name="sID" use="required"> <xs:simpleType> <xs:restriction base="xs:string"/> </xs:simpleType> </xs:attribute> </xs:complexType> <xs:complexType name="ServiceRequestType"> <xs:sequence> <xs:element ref="session" /> </xs:sequence> <xs:attribute ref="method" /> <xs:attribute ref="debug" /> </xs:complexType> <xs:complexType name="OrderTrackingServiceRequest"> <xs:complexContent> <xs:extension base="ServiceRequestType"> <xs:complexType> <xs:sequence> <xs:element name="OrderInclusionCriteria" type="xs:string" /> </xs:sequence> </xs:complexType> </xs:extension> </xs:complexContent> </xs:complexType> <xs:complexType name="Action"> <xs:complexContent> <xs:extension base="ServiceRequestType"> <xs:complexType> <xs:sequence> <xs:element name="makePayment"> <xs:complexType> <xs:attribute name="accountID" type="xs:string" /> <xs:attribute name="amount" type="xs:string" /> <xs:complexType> </xs:element> </xs:sequence> <xs:attribute name="aType" type="xs:string" /> </xs:complexType> </xs:extension> </xs:complexContent> </xs:complexType> </xs:schema>

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• 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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• 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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