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  • is there a signal emiter/consumer engine (like in Django) for .NET (C#)

    - by user118657
    Has .NET (C#) anything like Django's Signals engine? Our business logic become really complicated over few years of adding new features. I'm going to re-architecture it. Currently all features are very coupled that makes regression errors while changing something one one place - some other place may be broken. I really like Django's apps idea where separate applications introduce new functionality and are absolutely separate. Communication between apps is implemented though signals. I wounder if there is something in .NET that allows to divide project business to many separated "apps" (plug-ins, zones, modules, you name it) and make communication using some kind of "signals". For example we have simple order flow. We can add "coupon app" that if exists in the project adds abilities to use discount coupon. We can add "cross sale" module that if exists adds abilities to offer cross-sale products Email notification module that if exists adds abilities to send order email notifications. But in the same time all this modules are "self-contained" means that communication between them is done using emitting signals (ORDER_PROCCESS_START, ORDER_SUCCESS, etcs) and other modules can subscribe to this signals and process them in required way. This architecture is not related to web, all business logic is processed on the server side like without working with HTTP directly. I wonder if it's good architecture from code maintaining and testing point of few, is it possible to do this in .NET? Any drawbacks that I don't realize now?

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  • Netbeans, JPA Entity Beans in seperate projects. Unknown entity bean class

    - by Stu
    I am working in Netbeans and have my entity beans and web services in separate projects. I include the entity beans in the web services project however the ApplicaitonConfig.java file keeps getting over written and removing the entries I make for the entity beans in the associated jar file. My question is: is it required to have both the EntityBeans and the WebServices share the same project/jar file? If not what is the appropriate way to include the entity beans which are in the jar file? <?xml version="1.0" encoding="UTF-8"?> <persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"> <persistence-unit name="jdbc/emrPool" transaction-type="JTA"> <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> <jta-data-source>jdbc/emrPool</jta-data-source> <exclude-unlisted-classes>false</exclude-unlisted-classes> <properties> <property name="eclipselink.ddl-generation" value="none"/> <property name="eclipselink.cache.shared.default" value="false"/> </properties> </persistence-unit> </persistence> Based on Melc's input i verified that that the transaction type is set to JTA and the jta-data-source is set to the value for the Glassfish JDBC Resource. Unfortunately the problem still persists. I have opened the WAR file and validated that the EntityBean.jar file is the latest version and is located in the WEB-INF/lib directory of the War file. I think it is tied to the fact that the entities are not being "registered" with the entity manager. However i do not know why they are not being registered.

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  • How would I compare two Lists(Of <CustomClass>) in VB?

    - by Kumba
    I'm working on implementing the equality operator = for a custom class of mine. The class has one property, Value, which is itself a List(Of OtherClass), where OtherClass is yet another custom class in my project. I've already implemented the IComparer, IComparable, IEqualityComparer, and IEquatable interfaces, the operators =, <>, bool and not, and overriden Equals and GetHashCode for OtherClass. This should give me all the tools I need to compare these objects, and various tests comparing two singular instances of these objects so far checks out. However, I'm not sure how to approach this when they are in a List. I don't care about the list order. Given: Dim x As New List(Of OtherClass) From {New OtherClass("foo"), New OtherClass("bar"), New OtherClass("baz")} Dim y As New List(Of OtherClass) From {New OtherClass("baz"), New OtherClass("foo"), New OtherClass("bar")} Then (x = y).ToString should print out True. I need to compare the same (not distinct) set of objects in this list. The list shouldn't support dupes of OtherClass, but I'll have to figure out how to add that in later as an exception. Not interested in using LINQ. It looks nice, but in the few examples I've played with, adds a performance overhead in that bugs me. Loops are ugly, but they are fast :) A straight code answer is fine, but I'd like to understand the logic needed for such a comparison as well. I'm probably going to have to implement said logic more than a few times down the road.

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  • perl multithreading issue for autoincrement

    - by user3446683
    I'm writing a multi threaded perl script and storing the output in a csv file. I'm trying to insert a field called sl.no. in the csv file for each row entered but as I'm using threads, the sl. no. overlaps in most. Below is an idea of my code snippet. for ( my $count = 1 ; $count <= 10 ; $count++ ) { my $t = threads->new( \&sub1, $count ); push( @threads, $t ); } foreach (@threads) { my $num = $_->join; } sub sub1 { my $num = shift; my $start = '...'; #distributing data based on an internal logic my $end = '...'; #distributing data based on an internal logic my $next; for ( my $x = $start ; $x <= $end ; $x++ ) { my $count = $x + 1; #part of code from which I get @data which has name and age my $j = 0; if ( $x != 0 ) { $count = $next; } foreach (@data) { #j is required here for some extra code flock( OUTPUT, LOCK_EX ); print OUTPUT $count . "," . $name . "," . $age . "\n"; flock( OUTPUT, LOCK_UN ); $j++; $count++; } $next = $count; } return $num; } I need the count to be incremented which is the serial number for the rows that would be inserted in the csv file. Any help would be appreciated.

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  • Is it advisable to have an interface as the return type?

    - by wb
    I have a set of classes with the same functions but with different logic. However, each class function can return a number of objects. It is safe to set the return type as the interface? Each class (all using the same interface) is doing this with different business logic. protected IMessage validateReturnType; <-- This is in an abstract class public bool IsValid() <-- This is in an abstract class { return (validateReturnType.GetType() == typeof(Success)); } public IMessage Validate() { if (name.Length < 5) { validateReturnType = new Error("Name must be 5 characters or greater."); } else { validateReturnType = new Success("Name is valid."); } return validateReturnType; } Are there any pitfalls with unit testing the return type of an function? Also, is it considered bad design to have functions needing to be run in order for them to succeed? In this example, Validate() would have to be run before IsValid() or else IsValid() would always return false. Thank you.

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  • Sort string array by analysing date details in those strings

    - by Jason Evans
    I have a requirement for the project I'm working on right now which is proving a bit tricky for me. Basically I have to sort an array of items based on the Text property of those items: Here are my items: var answers = [], answer1 = { Id: 1, Text: '3-4 weeks ago' }, answer2 = { Id: 2, Text: '1-2 weeks ago' }, answer3 = { Id: 3, Text: '7-8 weeks ago' }, answer4 = { Id: 4, Text: '5-6 weeks ago' }, answer5 = { Id: 5, Text: '1-2 days ago' }, answer6 = { Id: 6, Text: 'More than 1 month ago' }; answers.push(answer1); answers.push(answer2); answers.push(answer3); answers.push(answer4); answers.push(answer5); answers.push(answer6); I need to analyse the Text property of each item so that, after the sorting, the array looks like this: answers[0] = { Id: 6, Text: 'More than 1 month ago' } answers[1] = { Id: 3, Text: '7-8 weeks ago' } answers[2] = { Id: 4, Text: '5-6 weeks ago' } answers[3] = { Id: 1, Text: '3-4 weeks ago' } answers[4] = { Id: 2, Text: '1-2 weeks ago' } answers[5] = { Id: 5, Text: '1-2 days ago' } The logic is that, the furthest away the date, the more high priority it is, so it should appear first in the array. So "1-2 days" is less of a priority then "7-8 weeks". So the logic is that, I need to extract the number values, and then the units (e.g. days, weeks) and somehow sort the array based on those details. Quite honestly I'm finding it very difficult to come up with a solution, and I'd appreciate any help.

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  • Expose webservice directly to webclients or keep a thin server-side script layer in between?

    - by max
    Hi, I'm developing a REST webservice (Java, Jersey). The people I'm doing this for want to directly access the webservice via Javascript. Some instinct tells me this is not a good idea, but I cannot really explain that instinct. My natural approach would have been to have the webservice do the real logic and database access, but also have some (relatively thin) server-side script layer (e.g. in PHP). Clients would talk to the PHP layer which in turn would talk to the webservice. (The webservice would be pretty local to the apache/PHP server and implicitly trust calls from the script layer. The script layer would take care of session management.) (Btw, I am not talking about just hiding the webservice behind an Apache which simply redirects calls.) But as I find myself at a lack of words/arguments to explain my instinct, I wonder whether my instinct is right - note that while I have been developing all kinds of software in all kinds of languages and frameworks for like 17 years, this is the first time I develop a webservice. So my question is basically: what are your opinions? Are there any standard setups? Is my instinct totally wrong? Or partially? ;P Many thanks, Max PS: I might add a few bits of information about the planned usage of the whole application: will be accessed by different kinds of users, partly general public, partly privileged thus, all major OS/browser combinations can be expected as clients however, writing the client is not my responsibility will potentially have very high load/traffic logic of webservice will later be massively expanded for another product which is basically a superset of the functionality of the current project there is a significant likelihood that at some point an API should be exposed which can be used by 3rd party developers - obviously, with some restrictions at some point, the public view of the product should become accessible via smartphones, too (in other words, maybe a customized version of the site to adapt to the smaller display and different input methods)

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  • How to configure multiple mappings using FluentHibernate?

    - by chris.baglieri
    First time rocking it with NHibernate/Fluent so apologies in advance if this is a naive question. I have a set of Models I want to map. When I create my session factory I'm trying to do all mappings at once. I am not using auto-mapping (though I may if what I am trying to do ends up being more painful than it ought to be). The problem I am running into is that it seems only the top map is taking. Given the code snippet below and running a unit test that attempts to save 'bar', it fails and checking the logs I see NHibernate is trying to save a bar entity to the foo table. While I suspect it's my mappings it could be something else that I am simply overlooking. Code that creates the session factory (note I've also tried separate calls into .Mappings): Fluently.Configure().Database(MsSqlConfiguration.MsSql2008 .ConnectionString(c => c .Server(@"localhost\SQLEXPRESS") .Database("foo") .Username("foo") .Password("foo"))) .Mappings(m => { m.FluentMappings.AddFromAssemblyOf<FooMap>() .Conventions.Add(FluentNHibernate.Conventions.Helpers .Table.Is(x => "foos")); m.FluentMappings.AddFromAssemblyOf<BarMap>() .Conventions.Add(FluentNHibernate.Conventions.Helpers .Table.Is(x => "bars")); }) .BuildSessionFactory(); Unit test snippet: using (var session = Data.SessionHelper.SessionFactory.OpenSession()) { var bar = new Bar(); session.Save(bar); Assert.NotNull(bar.Id); }

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  • C# Casting system.__comobject to class type

    - by ijrufus
    I have an Excel Add-In that I'm currently trying to set up a unit test framework for. For the unit tests I've followed this guide: http://blogs.msdn.com/b/varsha/archive/2010/08/17/writing-automated-test-cases-for-vsto-application.aspx It seems to work fine, until I want to return a class object from my interface. Specifying the class object as the return type throws a "return argument has an invalid type" exception when calling the method. Changing the return type from the class to an object allows me to call the method and get the object, but now I'm unable to cast it as the class and use it as intended, getting this exception message when I try: > Unable to cast COM object of type 'System.__ComObject' to class type > 'anaplan.Utility.XYCoordinates'. Instances of types that represent COM > components cannot be cast to types that do not represent COM > components; however they can be cast to interfaces as long as the > underlying COM component supports QueryInterface calls for the IID of > the interface. I've retrieved the Type name using VisualBasic.Information.TypeName and it's showing it as the class I expect. Is there any way to get the comobject cast back to the class? Or another way to access the properties it has? Or am I just being a bit stupid here?

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  • Draggable cards (touch enumeration) issue

    - by glitch
    I'm trying to let a player tap, drag and release a card from a fanned stack on the screen to a 4x4 field on the board. My cards are instantiated from a custom class that inherits from the UIImageView class. I started with the Touches sample app, and I modified the event handlers for touches to iterate over my player's card hand instead of the 3 squares the sample app allows you to move on screen. Everything works, until that is, I move the card I'm dragging near another card. I'm really drawing a blank here for the logic to get the cards to behave properly. Here's my code: - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { NSUInteger numTaps = [[touches anyObject] tapCount]; if(numTaps = 1) { for (UITouch *touch in touches) { [self dispatchFirstTouchAtPoint:[touch locationInView: self.boardCardView] forEvent:nil]; } } } -(void) dispatchFirstTouchAtPoint:(CGPoint)touchPoint forEvent:(UIEvent *)event { for (int i = 0; i<5; i++) { UIImageView *touchedCard = boardBuffer[i]; if (CGRectContainsPoint([touchedCard frame], touchPoint)) { [self animateFirstTouchAtPoint:touchPoint forView:touchedCard]; } } } - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { NSUInteger touchCount = 0; for (UITouch *touch in touches){ [self dispatchTouchEvent:[touch view] toPosition:[touch locationInView:self.boardCardView]]; touchCount++; } } My questions are: How do I get the touch logic to disallow other cards from being picked up by a dragging finger? Is there anyway I can only enumerate the objects that are directly below a player's finger and explicitly disable other objects from responding? Thanks!

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  • Design patterns for Caching Images in a MVC?

    - by Onema
    Hi, I'm designing an image cache system that will be used in an MVC CMS. The main purpose of the image cacher is to modify images: scale, crop, etc and cache them in the client site. I have created an image cache Model and Mapper that interact with the Database, to keep track of the images and know what kind of actions have been applied to them (scale, crop, etc). In addition to the Model and Mapper I have created a ImageCacher Class that is used by the API to manage the Model and image creation based on arguments passed by the client site, this class creates the images and generates the links to the images for the View. A coworker argued that I need to include the functionality of this last Class inside the Model, as the bulk of the logic should go in the model. I respectfully disagree with him since I feel the model's responsibility is to deal with the information about the images cached at the database level, and the responsibility of the ImageCacher Class is to create the url/image that we will be caching (keeping the single responsibility principle). In addition to this I believe that a model should not have Presentation-related features, like creating or showing images. Does anyone have any insight on this? is there a particular design pattern that would make this division of tasks clear and and the image cacher reusable? Should I add all the logic in the Model? Thank you.

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  • Absence of property syntax in Java

    - by Vojislav Stojkovic
    C# has syntax for declaring and using properties. For example, one can declare a simple property, like this: public int Size { get; set; } One can also put a bit of logic into the property, like this: public string SizeHex { get { return String.Format("{0:X}", Size); } set { Size = int.Parse(value, NumberStyles.HexNumber); } } Regardless of whether it has logic or not, a property is used in the same way as a field: int fileSize = myFile.Size; I'm no stranger to either Java or C# -- I've used both quite a lot and I've always missed having property syntax in Java. I've read in this question that "it's highly unlikely that property support will be added in Java 7 or perhaps ever", but frankly I find it too much work to dig around in discussions, forums, blogs, comments and JSRs to find out why. So my question is: can anyone sum up why Java isn't likely to get property syntax? Is it because it's not deemed important enough when compared to other possible improvements? Are there technical (e.g. JVM-related) limitations? Is it a matter of politics? (e.g. "I've been coding in Java for 50 years now and I say we don't need no steenkin' properties!") Is it a case of bikeshedding?

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  • Methods to see result fo a code change faster

    - by Can't Tell
    This question came to me when developing using Eclipse. I use JBoss Application Server and use hot code replacement. But this option requires that the 'build automatically' option to be enabled. This makes Eclipse build the workspace automatically (periodically or when a file is saved?) and for a large code base this takes too much time and processing which makes the machine freeze for a while. Also sometimes an error message is shown saying that hot code replacement failed. The question that I have is: is there a better way to see the result of a code change? Currently I have the following two suggestions: Have unit tests - this will allow to run a single test and see the result of a code change. ( But for a JavaEE application that uses EJBs is it easy to setup unit tests?) Use OSGi - which allows to add jars to the running system without bringing down the JVM. Any ideas on above suggestions or any other suggestion or a framework that allows to do this is welcome.

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  • How can I [simply] consume JSON Data in a Line of Business Web Application

    - by Atomiton
    I usually use JSON with jQuery to just return a string with html. However, I want to start to use Javascript objects in my code. What's the simplest way to get started using json objects on my page? Here's a sample Ajax call ( after $(document).ready( { ... }) of course: $('#btn').click(function(event) { event.preventDefault(); var out = $('#result'); $.ajax({ url: "CustomerServices.asmx/GetCustomersByInvoiceCount", success: function(msg) { // // Iterate through the json results and spit them out to a page? // }, data: "{ 'invoiceCount' : 100 }" }); }); My WebMethod: [WebMethod(Description="Gets customers with more than n invoices")] public List<Customer> GetCustomersByInvoiceCount(int? invoiceCount) { using (dbDataContext db = new dbDataContext()) { return db.Customers.Where(c => c.InvoiceCount >= invoiceCount); } } What gets returned: {"d":[{"__type":"Customer","Account":"1116317","Name":"SOME COMPANY","Address":"UNit 1 , 392 JOHN ST. ","LastTransaction":"\/Date(1268294400000)\/","HighestBalance":13922.34},{"__type":"Customer","Account":"1116318","Name":"ANOTHER COMPANY","Address":"UNIT #345 , 392 JOHN ST. ","LastTransaction":"\/Date(1265097600000)\/","HighestBalance":549.42}]} What I'd LIKE to know, is what are people generally doing with this returned json? Do you iterate through the properties and create an html table on the fly? Is there way to "bind" JSON data using a javascript version of reflection ( something like the .Net GridView Control ) Do you throw this returned data into a Javascript Object and then do something with it? An example of what I want to achieve is to have an plain ol' html page ( on a mobile device )with a list of a Salesperson's Customers. When one of those customers are clicked, the customer id gets sent to a webservice which retrieves the customer details that are relevant to a sales person. I know the SO talent pool is quite deep so I figured you all here would be able to guide in the right direction and give me a few ideas on the best way to approach this.

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  • Asynchronous SQL Operations

    - by Paul Hatcherian
    I've got a problem I'm not sure how best to solve. I have an application which updates a database in response to ad hoc requests. One request in particular is quite common. The request is an update that by itself is quite simple, but has some complex preconditions. For this request the business layer first requests a set of data from the data layer. The business logic layer evaluated the data from the database and parameters from the request, from this the action to be performed is determined, and the request's response message(s) are created. The business layer now executes the actual update command that is the purpose of the request. This last step is the problem, this command is dependent on the state of the database, which might have changed since the business logic ran. Locking down the data read in this operation across several round-trips to the database doesn't seem like a good idea either. Is there a 'best-practice' way to accomplish something like this? Thanks!

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  • Building a structure/object in a place other than the constructor

    - by Vishal Naidu
    I have different types of objects representing the same business entity. UIObject, PowershellObject, DevCodeModelObject, WMIObject all are different representation to the same entity. So say if the entity is Animal then I have AnimalUIObject, AnimalPSObject, AnimalModelObject, AnimalWMIObject, etc. Now the implementations of AnimalUIObject, AnimalPSObject, AnimalModelObject are all in separate assemblies. Now my scenario is I want to verify the contents of business entity Animal irrespective of the assembly it came from. So I created a GenericAnimal class to represent the Animal entity. Now in GenericAnimal I added the following constructors: GenericAnimal(AnimalUIObject) GenericAnimal(AnimalPSObject) GenericAnimal(AnimalModelObject) Basically I made GenericAnimal depend on all the underlying assemblies so that while verifying I deal with this abstraction. Now the other approach to do this is have GenericAnimal with an empty constructor an allow these underlying assemblies to have a Transform() method which would build the GenericAnimal. Both approaches have some pros and cons: The 1st approach: Pros: All construction logic is in one place in one class GenericAnimal Cons: GenericAnimal class must be touched every-time there is a new representation form. The 2nd approach: Pros: construction responsibility is delegated to the underlying assembly. Cons: As construction logic is spread accross assemblies, tomorrow if I need to add a property X in GenericAnimal then I have to touch all the assemblies to change the Transform method. Which approach looks better ? or Which would you consider a lesser evil ? Is there any alternative way better than the above two ?

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  • Can I transform this asynchronous java network API into a monadic representation (or something else

    - by AlecZorab
    I've been given a java api for connecting to and communicating over a proprietary bus using a callback based style. I'm currently implementing a proof-of-concept application in scala, and I'm trying to work out how I might produce a slightly more idiomatic scala interface. A typical (simplified) application might look something like this in Java: DataType type = new DataType(); BusConnector con = new BusConnector(); con.waitForData(type.getClass()).addListener(new IListener<DataType>() { public void onEvent(DataType t) { //some stuff happens in here, and then we need some more data con.waitForData(anotherType.getClass()).addListener(new IListener<anotherType>() { public void onEvent(anotherType t) { //we do more stuff in here, and so on } }); } }); //now we've got the behaviours set up we call con.start(); In scala I can obviously define an implicit conversion from (T = Unit) into an IListener, which certainly makes things a bit simpler to read: implicit def func2Ilistener[T](f: (T => Unit)) : IListener[T] = new IListener[T]{ def onEvent(t:T) = f } val con = new BusConnector con.waitForData(DataType.getClass).addListener( (d:DataType) => { //some stuff, then another wait for stuff con.waitForData(OtherType.getClass).addListener( (o:OtherType) => { //etc }) }) Looking at this reminded me of both scalaz promises and f# async workflows. My question is this: Can I convert this into either a for comprehension or something similarly idiomatic (I feel like this should map to actors reasonably well too) Ideally I'd like to see something like: for( d <- con.waitForData(DataType.getClass); val _ = doSomethingWith(d); o <- con.waitForData(OtherType.getClass) //etc )

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  • Writing a generic function that can take a Writer as well as an OutputStream

    - by ebruchez
    I wrote a couple of functions that look like this: def myWrite(os: OutputStream) = {} def myWrite(w: Writer) = {} Now both are very similar and I thought I would try to write a single parametrized version of the function. I started with a type with the two methods that are common in the Java OutputStream and Writer: type Writable[T] = { def close() : Unit def write(cbuf: Array[T], off: Int, len: Int): Unit } One issue is that OutputStream writes Byte and Writer writes Char, so I parametrized the type with T. Then I write my function: def myWrite[T, A[T] <: Writable[T]](out: A[T]) = {} and try to use it: val w = new java.io.StringWriter() myWrite(w) Result: <console>:9: error: type mismatch; found : java.io.StringWriter required: ?A[ ?T ] Note that implicit conversions are not applicable because they are ambiguous: both method any2ArrowAssoc in object Predef of type [A](x: A)ArrowAssoc[A] and method any2Ensuring in object Predef of type [A](x: A)Ensuring[A] are possible conversion functions from java.io.StringWriter to ?A[ ?T ] myWrite(w) I tried a few other combinations of types and parameters, to no avail so far. My question is whether there is a way of achieving this at all, and if so how. (Note that the implementation of myWrite will need, internally, to know the type T that parametrizes the write() method, because it needs to create a buffer as in new ArrayT.)

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  • LINQ2SQL: How to let a column accept null values as zero (0) in Self-Relation table

    - by Remon
    As described in the img, I got a parent-Children relation and since the ParentID not accepting null values (and I can't change to nullabel due to some restriction in the UI I have), how can I remove an existence relation between ReportDataSources in order to change the parent for them (here i want to set the parentId for one of them = 0) how could i do that since i cant change the ParentID directly and setting Parent = null is not valid public void SetReportDataSourceAsMaster(ReportDataSource reportDataSource) { //Some logic - not necessarily for this scenario //Reset Master this.ReportDataSources.ToList().ForEach(rds => rds.IsMaster = false); //Set Master reportDataSource.IsMaster = true; //Set Parent ID for the rest of the Reports data sources this.ReportDataSources.Where(rds => rds.ID != reportDataSource.ID).ToList().ForEach(rds => { //Change Parent ID rds.Parent = reportDataSource; //Remove filttering data rds.FilteringDataMembers.Clear(); //Remove Grouping Data rds.GroupingDataMembers.Clear(); }); //Delete parent HERE THE EXCEPTION THROWN AFTER CALLING SUBMITCHANGES() reportDataSource.Parent = null; //Other logic } Exception thrown after calling submitChanges An attempt was made to remove a relationship between a ReportDataSource and a ReportDataSource. However, one of the relationship's foreign keys (ReportDataSource.ParentID) cannot be set to null.

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  • Controlling race condition at startup.

    - by Will Hartung
    I have some code that I want to have some one time initialisation performed. But this code doesn't have a definite lifecycle, so my logic can be potentially invoked by multiple threads before my initialisation is done. So, I want to basically ensure that my logic code "waits" until initialisation is done. This is my first cut. public class MyClass { private static final AtomicBoolean initialised = new AtomicBoolean(false); public void initialise() { synchronized(initialised) { initStuff(); initialised.getAndSet(true); initialised.notifyAll(); } } public void doStuff() { synchronized(initialised) { if (!initialised.get()) { try { initialised.wait(); } catch (InterruptedException ex) { throw new RuntimeException("Uh oh!", ex); } } } doOtherStuff(); } } I basically want to make sure this is going to do what I think it's going to do -- block doStuff until the initialised is true, and that I'm not missing a race condition where doStuff might get stuck on a Object.wait() that will never arrive. Edit: I have no control over the threads. And I want to be able to control when all of the initialisation is done, which is why doStuff() can't call initialise(). I used an AtomicBoolean as it was a combination of a value holder, and an object I could synchronize. I could have also simply had a "public static final Object lock = new Object();" and a simple boolean flag. AtomicBoolean conveniently gave me both. A Boolean can not be modified. The CountDownLatch is exactly what I was looking for. I also considered using a Sempahore with 0 permits. But the CountDownLatch is perfect for just this task.

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  • Mixing stored procedures and ORM

    - by Jason
    The company I work for develops a large application which is almost entirely based on stored procedures. We use classic ASP and SQL Server and the major part of the business logic is contained inside those stored procedures. For example, (I know, this is bad...) a single stored procedure can be used for different purposes (insert, update, delete, make some calculations, ...). Most of the time, a stored procedure is used for operations on related tables, but this is not always the case. We are planning to move to ASP.NET in a near future. I have read a lot of posts on StackOverflow recommending that I move the business logic outside the database. The thing is, I have tried to convince the people who takes the decisions at our company and there is nothing I can do to change their mind. Since I want to be able to use the advantages of object-oriented programming, I want to map the tables to actual classes. So far, my solution is to use an ORM (Entity Framework 4 or nHibernate) to avoid mapping the objects manually (mostly to retrieve the data) and use some kind of Data Access Layer to call the existing stored procedures (for saving). I want your advice on this. Do you think it is a good solution? Any ideas?

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  • Custom Tile Layer Problem

    - by Myra
    Hi,I'm currently implementing logic on custom tile layers via OpenLayers function getTiles() { var res = this.map.getResolution(); var x = Math.round((bounds.left - this.maxExtent.left) / (res * this.tileSize.w)); var y = Math.round((this.maxExtent.top - bounds.top) / (res * this.tileSize.h)); var z = this.map.getZoom(); return ......; } What I need to is to carry this code in Google API v3. As I searched documentation I found this code to work with: var customtile = new google.maps.ImageMapType({ getTileUrl: function (coord, zoom) { .... .... } Unfortonately,I cannot convert logic in OpenLayers code to Google. As I know resolution is 180 * tileSize.w / Math.pow(2, zoom) //where tileSize is 256x256 Since Google projection is same with my tiles WGS84 boundary should be -180,-90,90,180 I need to calculate to extent coordinates,but in function getTileUrl,there are two arguments.One of which is zoom,but the other coord is some x,y pair which I dont understand what that is.What is that exactly ? How can I generalize formula for calculating tile numbers in Google Maps? Thank you Myra

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  • Django Admin Running Same Query Thousands of Times for Model

    - by Tom
    Running into an odd . . . loop when trying to view a model in the Django admin. I have three related models (code trimmed for brevity, hopefully I didn't trim something I shouldn't have): class Association(models.Model): somecompany_entity_id = models.CharField(max_length=10, db_index=True) name = models.CharField(max_length=200) def __unicode__(self): return self.name class ResidentialUnit(models.Model): building = models.CharField(max_length=10) app_number = models.CharField(max_length=10) unit_number = models.CharField(max_length=10) unit_description = models.CharField(max_length=100, blank=True) association = models.ForeignKey(Association) created = models.DateTimeField(auto_now_add=True) updated = models.DateTimeField(auto_now=True) def __unicode__(self): return '%s: %s, Unit %s' % (self.association, self.building, self.unit_number) class Resident(models.Model): unit = models.ForeignKey(ResidentialUnit) type = models.CharField(max_length=20, blank=True, default='') lookup_key = models.CharField(max_length=200) jenark_id = models.CharField(max_length=20, blank=True) user = models.ForeignKey(User) is_association_admin = models.BooleanField(default=False, db_index=True) show_in_contact_list = models.BooleanField(default=False, db_index=True) created = models.DateTimeField(auto_now_add=True) updated = models.DateTimeField(auto_now=True) _phones = {} home_phone = None work_phone = None cell_phone = None app_number = None account_cache_key = None def __unicode__(self): return '%s' % self.user.get_full_name() It's the last model that's causing the problem. Trying to look at a Resident in the admin takes 10-20 seconds. If I take 'self.association' out of the __unicode__ method for ResidentialUnit, a resident page renders pretty quickly. Looking at it in the debug toolbar, without the association name in ResidentialUnit (which is a foreign key on Resident), the page runs 14 queries. With the association name put back in, it runs a far more impressive 4,872 queries. The strangest part is the extra queries all seem to be looking up the association name. They all come from the same line, the __unicode__ method for ResidentialUnit. Each one is the exact same thing, e.g., SELECT `residents_association`.`id`, `residents_association`.`jenark_entity_id`, `residents_association`.`name` FROM `residents_association` WHERE `residents_association`.`id` = 1096 ORDER BY `residents_association`.`name` ASC I assume I've managed to create a circular reference, but if it were truly circular, it would just die, not run 4000x and then return. Having trouble finding a good Google or StackOverflow result for this.

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  • Help with HTTP Intercepting Proxy in Ruby?

    - by Philip
    I have the beginnings of an HTTP Intercepting Proxy written in Ruby: require 'socket' # Get sockets from stdlib server = TCPServer.open(8080) # Socket to listen on port 8080 loop { # Servers run forever Thread.start(server.accept) do |client| puts "** Got connection!" @output = "" @host = "" @port = 80 while line = client.gets line.chomp! if (line =~ /^(GET|CONNECT) .*(\.com|\.net):(.*) (HTTP\/1.1|HTTP\/1.0)$/) @port = $3 elsif (line =~ /^Host: (.*)$/ && @host == "") @host = $1 end print line + "\n" @output += line + "\n" # This *may* cause problems with not getting full requests, # but without this, the loop never returns. break if line == "" end if (@host != "") puts "** Got host! (#{@host}:#{@port})" out = TCPSocket.open(@host, @port) puts "** Got destination!" out.print(@output) while line = out.gets line.chomp! if (line =~ /^<proxyinfo>.*<\/proxyinfo>$/) # Logic is done here. end print line + "\n" client.print(line + "\n") end out.close end client.close end } This simple proxy that I made parses the destination out of the HTTP request, then reads the HTTP response and performs logic based on special HTML tags. The proxy works for the most part, but seems to have trouble dealing with binary data and HTTPS connections. How can I fix these problems?

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  • performance issue: difference between select s.* vs select *

    - by kamil
    Recently I had some problem in performance of my query. The thing is described here: poor Hibernate select performance comparing to running directly - how debug? After long time of struggling, I've finally discovered that the query with select prefix like: select sth.* from Something as sth... Is 300x times slower then query started this way: select * from Something as sth.. Could somebody help me, and asnwer why is that so? Some external documents on this would be really useful. The table used for testing was: SALES_UNIT table contains some basic info abot sales unit node such as name and etc. The only association is to table SALES_UNIT_TYPE, as ManyToOne. The primary key is ID and field VALID_FROM_DTTM which is date. SALES_UNIT_RELATION contains relation PARENT-CHILD between sales unit nodes. Consists of SALES_UNIT_PARENT_ID, SALES_UNIT_CHILD_ID and VALID_TO_DTTM/VALID_FROM_DTTM. No association with any tables. The PK here is ..PARENT_ID, ..CHILD_ID and VALID_FROM_DTTM The actual query I've done was: select s.* from sales_unit s left join sales_unit_relation r on (s.sales_unit_id = r.sales_unit_child_id) where r.sales_unit_child_id is null select * from sales_unit s left join sales_unit_relation r on (s.sales_unit_id = r.sales_unit_child_id) where r.sales_unit_child_id is null Same query, both uses left join and only difference is with select.

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