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  • DDD and Entity Base, Model using multiple identity types

    - by Thomas
    I have a model that looks like this: public interface IEntity { int Id { get; set; } } Then the idea is to have my entities inherit from this interface: public class User : IEntity { public int Id { get; set; } } However, one of my entities actually has a Guid as an identifier. public class UserSession { public Guid Id { get; set; } } I really would like all my entities inheriting from the same interface but that would force me to add an integer based identity column to the UserSession which is unnecessary since Guid is the identity, but it would keep the domain model nice since all entities would inherit from the same base. What options do I have in this scenario? Can I have two base interfaces, one for int and one for Guid? Should I add an identity column into the UserSession entity although it is unnecessary? I need the Guid so I can't just get rid of it and replace it with and integer. Any thoughts on best practices?

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  • How to get a JTextField event that started a pop up menu in Java ?

    - by Frank
    I have a JTextField that represents a day, such as "Sunday", when I left mouse click on it, it changes background color, when I right mouse click on it, a pop up menu comes up, after I click on a menu item, such as "1st of month", it gets the value, closes the menu and then change the bgcolor, my code looks like this : JTextField dayHeading=new JTextField("Su"); ...... final JPopupMenu Pmenu; JMenuItem menuItem; Pmenu=new JPopupMenu(); menuItem=new JMenuItem("1st of month"); Pmenu.add(menuItem); menuItem=new JMenuItem("2nd of month"); Pmenu.add(menuItem); ...... menuItem.addMouseListener(new MouseAdapter() { public void mouseReleased(final MouseEvent e) { System.out.println(((JMenuItem)e.getComponent()).getText()); onHeadingClicked(e); // Error : java.lang.ClassCastException: javax.swing.JMenuItem cannot be cast to javax.swing.JTextField // How to get the orininal JTextField event that started this pop up menu, so I can pass it onto onHeadingClicked() ? } }); ...... dayHeading.setEditable(false); dayHeading.setFocusable(false); dayHeading.addMouseListener(new MouseAdapter() { public void mouseReleased(final MouseEvent evt) { if (SwingUtilities.isLeftMouseButton(evt)) onHeadingClicked(evt); else if (SwingUtilities.isRightMouseButton(evt)) Pmenu.show(evt.getComponent(),evt.getX(),evt.getY()); } }); ...... void onHeadingClicked(final java.awt.event.MouseEvent evt) { final javax.swing.JTextField fld=(javax.swing.JTextField) evt.getSource(); ... } My question is : in the menuItem.addMouseListener section, how to get the orininal JTextField event that started this pop up menu, so I can pass it onto onHeadingClicked() ?

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  • core data saving in textboxes in table view controller

    - by user1489709
    I have created a five column (text boxes) cell (row) in table view controller with an option of add button. When a user clicks on add button, a new row (cell) with five column (text boxe) is added in a table view controller with null values. I want that when user fills the text boxes the data should get saved in database or if he changes any data in previous text boxes also it get saved. this is my save btn coding.. -(void)textFieldDidEndEditing:(UITextField *)textField { row1=textField.tag; NSLog(@"Row is %d",row1); path = [NSIndexPath indexPathForRow:row1 inSection:0]; Input_Details *inputDetailsObject1=[self.fetchedResultsController objectAtIndexPath:path]; /* Update the Input Values from the values in the text fields. */ EditingTableViewCell *cell; cell = (EditingTableViewCell *)[self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:row1 inSection:0]]; inputDetailsObject1.mh_Up= cell.cell_MH_up.text; inputDetailsObject1.mh_down=cell.cell_MH_dn.text; inputDetailsObject1.sewer_No=[NSNumber numberWithInt:[cell.cell_Sewer_No.text intValue]]; inputDetailsObject1.mhup_gl=[NSNumber numberWithFloat:[cell.cell_gl_MHUP.text floatValue]]; inputDetailsObject1.mhdn_gl=[NSNumber numberWithFloat:[cell.cell_gl_MHDN.text floatValue]]; inputDetailsObject1.pop_Ln=[NSNumber numberWithInt:[cell.cell_Line_pop.text intValue]]; inputDetailsObject1.sew_len=[NSNumber numberWithFloat:[cell.cell_Sewer_len.text floatValue]]; [self saveContext]; NSLog(@"Saving the MH_up value %@ is saved in save at index path %d",inputDetailsObject1.mh_Up,row1); [self.tableView reloadData]; }

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  • Using jQuery with Windows 8 Metro JavaScript App causes security error

    - by patridge
    Since it sounded like jQuery was an option for Metro JavaScript apps, I was starting to look forward to Windows 8 dev. I installed Visual Studio 2012 Express RC and started a new project (both empty and grid templates have the same problem). I made a local copy of jQuery 1.7.2 and added it as a script reference. <!-- SomeTestApp references --> <link href="/css/default.css" rel="stylesheet" /> <script src="/js/jquery-1.7.2.js"></script> <script src="/js/default.js"></script> Unfortunately, as soon as I ran the resulting app it tosses out a console error: HTML1701: Unable to add dynamic content ' a' A script attempted to inject dynamic content, or elements previously modified dynamically, that might be unsafe. For example, using the innerHTML property to add script or malformed HTML will generate this exception. Use the toStaticHTML method to filter dynamic content, or explicitly create elements and attributes with a method such as createElement. For more information, see http://go.microsoft.com/fwlink/?LinkID=247104. I slapped a breakpoint in a non-minified version of jQuery and found the offending line: div.innerHTML = " <link/><table></table><a href='/a' style='top:1px;float:left;opacity:.55;'>a</a><input type='checkbox'/>"; Apparently, the security model for Metro apps forbids creating elements this way. This error doesn't cause any immediate issues for the user, but given its location, I am worried it will cause capability-discovery tests in jQuery to fail that shouldn't. I definitely want jQuery $.Deferred for making just about everything easier. I would prefer to be able to use the selector engine and event handling systems, but I would live without them if I had to. How does one get the latest jQuery to play nicely with Metro development?

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  • QT4 Designer - Implement Widget

    - by MOnsDaR
    I'm currently trying to get into QT4 and figure out a workflow for myself. While trying to create a widget which allows the user to connect to a hostname:port some questions appeared. The widget itself contains a LineEdit for entering the hostname, a SpinBox for entering the port and a PushButton which should emit a connect(QString hostname, unsigned int port) signal. In QTDesigner I created the necessary Form. It is saved as a .ui-File. Now the big question is how could I implement the widget? Is there a place in QTDesigner where I could add my signal to the Widget? Where could I add custom Properties? I've learned in another tutorial, which showed how to create a Widget in C++, how signals, slots, Q_PROPERTIES etc are defined and added to the widget. But there is no sourcecode in QTDesigner. Another option would be to generate sourcecode using uic. But the header says, that another generate would overwrite any changes to the sourcefiles. So how can I create a QT-widget completely with my own signals, slots and properties by using the QTDesigner for creating the UI and not having to recode everything whenever the UI is changing. Is there some kind of Roundtrip-Engineering? If thats not possible: Whats the sense of creating a Widget with QTDesigner then?

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  • how to change ASP.NET Configuration tool connection string

    - by Zviadi
    Hello, how can I change ASP.NET Configuration tool-s connection string name? (Which connection string will ASP.NET Configuration tool will use) I'm learning ASP.NET and everywhere and in book that I'm reading now theres connection string named: LocalSqlServer. I want to use my local sql server database instead of sql express to store Roles, Membership and other data. I have used aspnet_regsql.exe to create needed data structures in my database. after that I changed my web.config to look like: <connectionStrings> <remove name="LocalSqlServer"/> <add name="LocalSqlServer" connectionString="Server=(LOCAL); Database=MyDatabase;Integrated Security=True" providerName="System.Data.SqlClient" /> </connectionStrings> but when I run ASP.NET Configuration tool it says that: "The connection name 'ApplicationServices' was not found in the applications configuration or the connection string is empty." ASP.NET Configuration tool uses connection string named: ApplicationServices not LocalSqlServer. cause of that I have to modify web.config to: <connectionStrings> <add name="ApplicationServices" connectionString="Server=(LOCAL); Database=MyDatabase;Integrated Security=True" providerName="System.Data.SqlClient" /> </connectionStrings> and everything works fine. I wish to know why the hell my web site uses connection string named: ApplicationServices and all books and online documentations uses LocalSqlServer? and how to change it to LocalSqlServer? I have: Windows 7 Sql Server 2008 R2 Visual Studio 2010 Premium Project type is website

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  • Set size of JTable in JScrollPane and in JPanel with the size of the JFrame

    - by user1761818
    I want the table with the same width as the frame and also when I resize the frame the table need to be resized too. I think setSize() of JTable doesn't work correctly. Can you help me? import java.awt.Color; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.SwingUtilities; public class Main extends JFrame { public Main() { setSize(400, 600); String[] columnNames = {"A", "B", "C"}; Object[][] data = { {"Moni", "adsad", 2}, {"Jhon", "ewrewr", 4}, {"Max", "zxczxc", 6} }; JTable table = new JTable(data, columnNames); JScrollPane tableSP = new JScrollPane(table); int A = this.getWidth(); int B = this.getHeight(); table.setSize(A, B); JPanel tablePanel = new JPanel(); tablePanel.add(tableSP); tablePanel.setBackground(Color.red); add(tablePanel); setTitle("Marks"); setLocationRelativeTo(null); setDefaultCloseOperation(EXIT_ON_CLOSE); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { public void run() { Main ex = new Main(); ex.setVisible(true); } }); } }

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  • Adding an unknown number of JComponents to a JPanel

    - by Matthew
    Good day, I am building an Applet (JApplet to be exact) and I sub divided that into two panels. The top panel is called DisplayPanel which is a custom class that extends JPanel. The bottom panel is called InputPanel which also extends JPanel. As mentioned above, I can add those two Panel's to the applet and they display fine. The next thing that I would like to do is have the InputPanel be able to hold a random number of JComponent Objects all listed veritcally. This means that the InputPanel should be able to have JButtons, JLabels, JTextFields etc thrown at it. I then want the InputPanel to display some sort of scrolling capability. The catch is that since these two panels are already inside my applet, I need the InputPanel to stay the same size as it was given when added to the Applet. So for example, if my applet (from the web-browser html code) was given the size 700,700, and then the DisplayPanel was 700 by 350, and the InputPanel was below it with the same dimensions, I want to then be able to add lots of JComponents like buttons, to the InputPanel and the panel would stay 700 x 350 in the same position that it is at, only the panel would have scroll bars if needed. I've played with many different combinations of JScrollPane, but just cannot get it. Thank you.

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  • Strongly Typed DataSet column requires custom type to implement IXmlSerializable?

    - by Phil
    I have a strongly typed Dataset with a single table with three columns. These columns all contain custom types. DataColumn1 is of type Parent DataColumn2 is of type Child1 DataColumn3 is of type Child2 Here is what these classes look like: [Serializable] [XmlInclude(typeof(Child1)), XmlInclude(typeof(Child2))] public abstract class Parent { public int p1; } [Serializable] public class Child1 :Parent { public int c1; } [Serializable] public class Child2 : Parent { public int c1; } now, if I add a row with DataColumn1 being null, and DataColumns 2 and 3 populated and try to serialize it, it works: DataSet1 ds = new DataSet1(); ds.DataTable1.AddDataTable1Row(null, new Child1(), new Child2()); StringBuilder sb = new StringBuilder(); using (StringWriter writer = new StringWriter(sb)) { ds.WriteXml(writer);//Works! } However, if I try to add a value to DataColumn1, it fails: DataSet1 ds = new DataSet1(); ds.DataTable1.AddDataTable1Row(new Child1(), new Child1(), new Child2()); StringBuilder sb = new StringBuilder(); using (StringWriter writer = new StringWriter(sb)) { ds.WriteXml(writer);//Fails! } Here is the Exception: "Type 'WindowsFormsApplication4.Child1, WindowsFormsApplication4, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' does not implement IXmlSerializable interface therefore can not proceed with serialization." I have also tried using the XmlSerializer to serialize the dataset, but I get the same exception. Does anyone know of a way to get around this where I don't have to implement IXmlSerializable on all the Child classes? Alternatively, is there a way to implement IXmlSerializable keeping all default behavior the same (ie not having any class specific code in the ReadXml and WriteXml methods)

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  • Forum achievements on a phpBB3 board?

    - by VIVA LA NWO
    I recently started a new community. The forum software is phpBB3, and so far so good. In an attempt to make my community more unique and interesting, I had to idea of having user achievements. Let me give you a quick run-down. Each user has achievements that they can earn (these will probably be across all users), for example an achievement for when a user hits 1,000 posts, when they upload an avatar, when one of their topics gets 1,000 views and so on. Each achievement has points, for example an achievement like uploading an avatar will be 10 points and reaching 10,000 points will grant 50 achievement points. If anyone here plays World of Warcraft you may be seeing where I'm getting the ideas from. :) What I'm struggling to get my head around though is how exactly to code this... I could keep a record of all users activity and add it to a special database table possibly, and then check via cron every minute or so if any user has met achievement criteria... but then I also want it controllable through the ACP so I can easily add new achievements and change their points etc. My mind is pretty blank when it comes to anything but the most simple things. What I really posted here for was feedback on the idea and how you all think I should go about doing this. The coding part should be pretty simple for me once I get my head around how phpBBB MODs need to be written. Thanks for reading, and I look forward to your replies. :)

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  • (nested) user controls within a mvp pattern causing sporadic problems

    - by LLEA
    hi everyone, I have a serious problem with nested user controls (UCs) in WinForms while trying to implement the mvp pattern (passive view). The project consists of one model (designed as a singleton) and a set of different presenters with corresponding view interfaces. To avoid one huge view interface and therefore an overloaded main UI, I decided to make use of a set of different UCs. Each UC has one view interface and one presenter that can access the model. But there are nested UCs: meaning that one specialised UC implements sort of a basic UC. The main UI just represents a container for all those UCs. So far, so good (if not, please ask)?! There are two problems that I am facing now (but I guess both are of the same origin): From time to time it is not possible anymore to load the UCs and test them within the Visual Studio 2008 User Control Test Container. The error message just says that a project with an output type of class library cannot be started directly etc. I can "handle" that by unloading all UC projects and reloading them afterwards. (I guess the references to all mvp components and other UCs are then updated). Assuming that the implementation of my mvp pattern is okay and all those UCs are testable within the VS Test Container at a certain time - there is the biggest problem still left: I am not able to add any UC (even the basic and unnested ones) to a simple Form (UI). The error message: error message.jpg Could it be that my basic UC causes all these Problems?! It consists of two simple ComboBoxes and implements a basic presenter and basic view interface. Whenever I add this UC to a different UC the VS designer adds two references to the public getter methods of the UC as resources. I then manually remove those resources from the resx-file and commend the corresponding lines in the designer file. thx in advance

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  • movieClip in Array displays null, and aren't showing up on stage.addChild(Array[i])

    - by jtdino
    i am new to Actionscript3, i need to know why i keep getting Parameter child must be non-null. And my code won't display 5 enemyBlock objects onto the stage but only just one. any tips and help will be much appreciated. thanks in advance. returns: TypeError: Error #2007: Parameter child must be non-null. at flash.display::DisplayObjectContainer/addChild() at flash.display::Stage/addChild() at BlockDrop_fla::MainTimeline/EnemyBlockPos() at BlockDrop_fla::MainTimeline/frame2() // declare varibles var isEnemyMoving:Boolean = false; var enemyArray:Array; var enemyBlock:MovieClip = new EnemyBlock(); // assign EnemyBlock class to enemyBlock var enemyBlockMC:MovieClip; var count:int = 5; var mapWidth:Number = 800; var mapHeight:Number = 600; function EnemyBlockPos() :void { // assign new MovieClip not null enemyBlockMC = new MovieClip; enemyArray = new Array(); for(var i=1; i<= count; i++){ // add class to MC enemyBlockMC.addChild(enemyBlock); // randomize position enemyBlock.x = Math.round(Math.random()*mapWidth); enemyBlock.y = Math.round(Math.random()*mapHeight); // set motion enemyBlock.movement = 5; // add MC to array enemyArray.push(enemyBlockMC); } for (var w = 1; w <= enemyArray.length; w++) { addChild(enemyArray[w]); } } // endOf EnemyBlockPos

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  • Liskov Substition and Composition

    - by FlySwat
    Let say I have a class like this: public sealed class Foo { public void Bar { // Do Bar Stuff } } And I want to extend it to add something beyond what an extension method could do....My only option is composition: public class SuperFoo { private Foo _internalFoo; public SuperFoo() { _internalFoo = new Foo(); } public void Bar() { _internalFoo.Bar(); } public void Baz() { // Do Baz Stuff } } While this works, it is a lot of work...however I still run into a problem: public void AcceptsAFoo(Foo a) I can pass in a Foo here, but not a super Foo, because C# has no idea that SuperFoo truly does qualify in the Liskov Substitution sense...This means that my extended class via composition is of very limited use. So, the only way to fix it is to hope that the original API designers left an interface laying around: public interface IFoo { public Bar(); } public sealed class Foo : IFoo { // etc } Now, I can implement IFoo on SuperFoo (Which since SuperFoo already implements Foo, is just a matter of changing the signature). public class SuperFoo : IFoo And in the perfect world, the methods that consume Foo would consume IFoo's: public void AcceptsAFoo(IFoo a) Now, C# understands the relationship between SuperFoo and Foo due to the common interface and all is well. The big problem is that .NET seals lots of classes that would occasionally be nice to extend, and they don't usually implement a common interface, so API methods that take a Foo would not accept a SuperFoo and you can't add an overload. So, for all the composition fans out there....How do you get around this limitation? The only thing I can think of is to expose the internal Foo publicly, so that you can pass it on occasion, but that seems messy.

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  • How to do buffered intersection checks on an IPoint?

    - by Quigrim
    How would I buffer an IPoint to do an intersection check using IRelationalOperator? I have, for arguments sake: IPoint p1 = xxx; IPoint p2 = yyy; IRelationalOperator rel1 = (IRelationalOperator)p1; if (rel.Intersects (p2)) // Do something But now I want to add a tolerance to my check, so I assume the right way to do that is by either buffering p1 or p2. Right? How do I add such a buffer? Note: the Intersects method I am using is an extension method I wrote to simplify my code. Here it is: /// <summary> /// Returns true if the IGeometry is intersected. /// This method negates the Disjoint method. /// </summary> /// <param name="relOp">The rel op.</param> /// <param name="other">The other.</param> /// <returns></returns> public static bool Intersects ( this IRelationalOperator relOp, IGeometry other) { return (!relOp.Disjoint (other)); }

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  • Combining the jquery Calendar picker with the jquery validation and getting them to play nice?

    - by MBonig
    I'm just starting to get into jquery/javascript programming so this may be a beginner question but I sure can't seem to find anything about it. I have a text field on a form. I've used the JQuery UI Calendar picker to make data entry better. I've also added jquery validation to ensure that if the user enters the date by hand that it's still valid. Here is the html: <input class="datepicker" id="Log_ServiceStartTime_date" name="Log_ServiceStartTime_date" type="text" value="3/16/2010"></input> and javascript: $('form').validate(); $('#Log_ServiceStartTime_date').rules('add','required'); $('#Log_ServiceStartTime_date').rules('add','date'); the problem I'm having is this: If a user puts in a bad date, or no date at all, the validation correctly kicks in and the error description displays. However, if the user clicks on the textbox to bring up the calendar picker and selects a date, the date fills into the field but the validation does not go away. If the user clicks into the textbox and then back out, the validation correctly goes away. How can I get the calendar picker to kick off the validation routine once a date is selected? thanks

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  • Get location of element you just pushed into vector C++

    - by Satchmo Brown
    I am curious about how pushing back into a vector works. I want a way to push back an element and then be able to add it's location in the vector to a double array serving as a type of map. Something like this: // Create a bomb Bomb b; b.currentTime = SDL_GetTicks(); b.explodeTime = SDL_GetTicks() + 3000; b.owner = player; b.power = 2; b.x = x; b.y = y; bombVec.push_back(b); bombs[y][x] = THIS_IS_WHAT_I_WANT; This way when I explode the bomb, I can check the map and then have an ID in the vector to deal with. Every non bomb square will have a -1. Also, just curious. Imagine I have 3 elements in a vector. I delete the second one and then add another. Does the new element go in the same location as the one that was deleted? Thanks!

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  • Is there unreachable code in this snippet? I don't think so, but Resharper is telling me otherwise.

    - by The Matt
    I have the following method I came across in a code review. Inside the loop Resharper is telling me that if (narrativefound == false) is incorrect becuase narrativeFound is always true. I don't think this is the case, because in order to set narrativeFound to true it has to pass the conditional string compare first, so how can it always be true? Am I missing something? Is this a bug in Resharper or in our code? public Chassis GetChassisForElcomp(SPPA.Domain.ChassisData.Chassis asMaintained, SPPA.Domain.ChassisData.Chassis newChassis) { Chassis c = asMaintained; List<Narrative> newNarrativeList = new List<Narrative>(); foreach (Narrative newNarrative in newChassis.Narratives) { bool narrativefound = false; foreach (Narrative orig in asMaintained.Narratives) { if (string.Compare(orig.PCode, newNarrative.PCode) ==0 ) { narrativefound = true; if (newNarrative.NarrativeValue.Trim().Length != 0) { orig.NarrativeValue = newNarrative.NarrativeValue; newNarrativeList.Add(orig); } break; } if (narrativefound == false) { newNarrativeList.Add(newNarrative); } } } c.SalesCodes = newChassis.SalesCodes; c.Narratives = newNarrativeList; return c; }

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  • Getting data from child controls loaded programmatically

    - by Farinha
    I've created 2 controls to manipulate a data object: 1 for viewing and another for editing. On one page I load the "view" User Control and pass data to it this way: ViewControl control = (ViewControl)LoadControl("ViewControl.ascx"); control.dataToView = dataObject; this.container.Controls.Add(control); That's all fine and inside the control I can grab that data and display it. Now I'm trying to follow a similar approach for editing. I have a different User Control for this (with some textboxes for editing) to which I pass the original data the same way I did for the view: EditControl control = (EditControl)LoadControl("EditControl.ascx"); control.dataToEdit = dataObject; this.container.Controls.Add(control); Which also works fine. The problem now is getting to this data. When the user clicks a button I need to fetch the data that was edited and do stuff with it. What's happening is that because the controls are being added programmatically, the data that the user changed doesn't seem to be accessible anywhere. Is there a solution for this? Or is this way of trying to keep things separated and possibly re-usable not possible? Thanks in advance.

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  • Active Directory Membership Provider - how to expand on this?

    - by Jaxidian
    I'm working on getting an MVC app up and running via AD Membership Provider and I'm having some issues figuring this out. I have a base configuration setup and working when I login as [email protected] + password. <connectionStrings> <add name="MyConnString" connectionString="LDAP://domaincontroller/OU=Product Users,DC=my,DC=domain,DC=com" /> </connectionStrings> <membership defaultProvider="MyProvider"> <providers> <clear /> <add name="MyProvider" connectionStringName="MyConnString" connectionUsername="my.domain.com\service_account" connectionPassword="biguglypassword" type="System.Web.Security.ActiveDirectoryMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" /> </providers> </membership> However, I'd LIKE to do some other things and I'm not sure how to go about them. Login without typing the domain (i.e. the "@my.domain.com"). I realize that this could only work if I limit myself to just one domain - that's fine. Organize users in up to N different OUs within a single OU. As you can tell from my current connection string, I'm authenticating users in my Product Users OU. I would LIKE to create OUs for various companies within this OU and put the users into those OUs. How can I authenticate across all of these different OUs? I'm trying to figure out how the Active Directory Membership Provider ties in with the Profile and Role providers. Are there AD versions of those too or am I stuck with SQL, home-grown, or finding something somebody else has coded up? Many thanks!!

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  • Is the Java classpath final after JVM startup?

    - by Jens
    Hi, I have read a lot about the Java class loading process lately. Often I came across texts that claimed that it is not possible to add classes to the classpath during runtime and load them without class loader hackery (URLClassLoaders etc.) As far as I know classes are loaded dynamically. That means their bytecode representation is only loaded and transformed to a java.lang.Class object when needed. So shouldn't it be possible to add a JAR or *.class file to the classpath after the JVM started and load those classes, provided they haven't been loaded yet? (To be clear: In this case the classpath is simple folder on the filesystem. "Adding a JAR or *.class file" simply means dropping them in this folder.) And if not, does that mean that the classpath is searched on JVM startup and all fully qualified names of the found classes are cached in an internal "list"? It would be nice of you if you could point me to some sources in your answers. Preferably the offical SUN documentation: Sun JVM Spec. I have read the spec but could not find anything about the classpath and if it's finalized on JVM startup. P.s. This is a theoretical question. I just want to know if it is possible. There is nothing practical I want to achieve. There is just my thirst for knowledge :)

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  • How do I make my ArrayList Thread-Safe? Another approach to problem in Java?

    - by thechiman
    I have an ArrayList that I want to use to hold RaceCar objects that extend the Thread class as soon as they are finished executing. A class, called Race, handles this ArrayList using a callback method that the RaceCar object calls when it is finished executing. The callback method, addFinisher(RaceCar finisher), adds the RaceCar object to the ArrayList. This is supposed to give the order in which the Threads finish executing. I know that ArrayList isn't synchronized and thus isn't thread-safe. I tried using the Collections.synchronizedCollection(c Collection) method by passing in a new ArrayList and assigning the returned Collection to an ArrayList. However, this gives me a compiler error: Race.java:41: incompatible types found : java.util.Collection required: java.util.ArrayList finishingOrder = Collections.synchronizedCollection(new ArrayList(numberOfRaceCars)); Here is the relevant code: public class Race implements RaceListener { private Thread[] racers; private ArrayList finishingOrder; //Make an ArrayList to hold RaceCar objects to determine winners finishingOrder = Collections.synchronizedCollection(new ArrayList(numberOfRaceCars)); //Fill array with RaceCar objects for(int i=0; i<numberOfRaceCars; i++) { racers[i] = new RaceCar(laps, inputs[i]); //Add this as a RaceListener to each RaceCar ((RaceCar) racers[i]).addRaceListener(this); } //Implement the one method in the RaceListener interface public void addFinisher(RaceCar finisher) { finishingOrder.add(finisher); } What I need to know is, am I using a correct approach and if not, what should I use to make my code thread-safe? Thanks for the help!

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  • Lazy loading is not working for one to many

    - by Shire
    Any 1-M that use the primary key of the parent table, but any 1-M that uses a different column does not work. It generates the SQL correctly, but put the value of the key into the SQL instead of the column value I want. Example mapping: public TemplateMap() { Table("IMPORT"); LazyLoad(); Id(x => x.ImportId).Column("IMPORT_ID").GeneratedBy.Assigned(); Map(x => x.ImportSetId).Column("IMPORTSET_ID"); HasMany(x => x.GoodChildren) .Access.CamelCaseField() .KeyColumns.Add("IMPORT_ID") .Cascade.Delete() .Inverse(); HasMany(x => x.BadChildren) .Access.CamelCaseField() .KeyColumns.Add("IMPORTSET_ID") .Cascade.Delete() .Inverse(); } Lazy loading works for GoodChildren, but not for BadChildren. The SQL statement is correct for both children. But the wrong values are use. If the value of IMPORT_ID is 10 and the value of IMPORTSET_ID is 12. The value 10 will be used for the IMPORTSET_ID in the SQL for BadChildren instead of 12. Anyone have any ideas what I need to change to get BadChildren to work correctly? Note: GoodChildren links to IMPORT_ID on Template BadChildren links to IMPORTSET_ID on Template

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  • EF 4.0 Code only assocation from abstract to derived

    - by Jeroen
    Using EF 4.0 Code only i want to make an assocation between an abstract and normal class. I have class 'Item', 'ContentBase' and 'Test'. 'ContentBase' is abstract and 'Test' derives from it. 'ContentBase' has a property 'Item' that links to an instance of 'Item'. So that 'Test.Item' or any class that derives from 'ContentBase' has an 'Item' navigation property. In my DB every record for Test has a matching record for Item. public class Item { public int Id { get; set;} } public abstract class ContentBase { public int ContentId { get; set;} public int Id { get; set;} public Item Item { get; set;} } public class Test : ContentBase { public string Name { get; set;} } now some init code public void SomeInitFunction() { var itemConfig = new EntityConfiguration<Item>(); itemConfig.HasKey(p => p.Id); itemConfig.Property(p => p.Id).IsIdentity(); this.ContextBuilder.Configurations.Add(itemConfig); var testConfig = new EntityConfiguration<Test>(); testConfig.HasKey(p => p.ContentId); testConfig.Property(p => p.ContentId).IsIdentity(); // the problem testConfig.Relationship(p => p.Item).HasConstraint((p, q) => p.Id == q.Id); this.ContextBuilder.Configurations.Add(testConfig); } This gives an error: A key is registered for the derived type 'Test'. Keys must be registered for the root type 'ContentBase'. anyway i try i get an error. What am i a doing wrong?

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  • Achieving Thread-Safety

    - by Smasher
    Question How can I make sure my application is thread-safe? Are their any common practices, testing methods, things to avoid, things to look for? Background I'm currently developing a server application that performs a number of background tasks in different threads and communicates with clients using Indy (using another bunch of automatically generated threads for the communication). Since the application should be highly availabe, a program crash is a very bad thing and I want to make sure that the application is thread-safe. No matter what, from time to time I discover a piece of code that throws an exception that never occured before and in most cases I realize that it is some kind of synchronization bug, where I forgot to synchronize my objects properly. Hence my question concerning best practices, testing of thread-safety and things like that. mghie: Thanks for the answer! I should perhaps be a little bit more precise. Just to be clear, I know about the principles of multithreading, I use synchronization (monitors) throughout my program and I know how to differentiate threading problems from other implementation problems. But nevertheless, I keep forgetting to add proper synchronization from time to time. Just to give an example, I used the RTL sort function in my code. Looked something like FKeyList.Sort (CompareKeysFunc); Turns out, that I had to synchronize FKeyList while sorting. It just don't came to my mind when initially writing that simple line of code. It's these thins I wanna talk about. What are the places where one easily forgets to add synchronization code? How do YOU make sure that you added sync code in all important places?

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  • How to place images on top of each other in java

    - by Haxed
    Hi, I have a background image of a road, which I have displayed on a JFrame using an ImageIcon. I want to put a car on top of that background image at a certain (x,y) location. I tried using another ImageIcon and the background does not appear when I run the program , however the car does. import javax.swing.ImageIcon; import javax.swing.JFrame; import javax.swing.JLabel; public class Gui extends JFrame { private ImageIcon northcar = new ImageIcon("src/north.gif"); private ImageIcon usIcon = new ImageIcon("src/trafficLight.jpg"); public Gui() { add(new JLabel(usIcon)); // background image does not appear after the i added the northcar label add(new JLabel(northcar)); // this picture can be seen } public static void main(String[] args) { Gui frame = new Gui(); frame.setTitle("TestImageIcon"); frame.setLocationRelativeTo(null); // Center the frame frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setBounds(0, 0, 650, 650); frame.setVisible(true); } } I heard about using a canvas but have no clue. Any ideas ? Many Thanks

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