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• Regarding Toplink Fetching Policy

  - by Chandu

  Hi, I'm working for a Swing Project and the technologies used are netbeans with Toplink essentials, mysql. The Problem I'm facing is the entity object dosn't get updated after insertions take place while calling a getter collection of the foreign key property. Ex: I have 2 tables Table1,Table2. I have sno column, id column as a primary key in Table1 & is Foreign Key in Table2. Through find method I just get the particular sno object(existed in table 1) set some values persisted to table2 & committed the transaction. When I select the same sno object through find method & gets its collection from Table2 through the getTable2Collection() of the bean(as it is already created in bean by toplink essential) I'm unable to get the latest added record except that all other records of it are displayed. After I close the application & opening it then the new record gets reflected while calling the same sno through the above process. I came to know that this is a kind of lazy fetching and there should be some way of fetch policy to be changed to make the entity object get updated with the changes. So Please help me in this regard. Regards, Chandu

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• Entity Framework Update Error in ASP.NET Mvc with related entity

  - by Barry

  I have run into a problem which have searched and tried everything i can to find a solution but to no avail. I am using the same repository and context throughout the process I have a booking entity and a userExtension Entity Below is my image i then get my form collection back from my page and create a new booking public ActionResult Create(FormCollection collection) { Booking toBooking = new Booking(); i then do some validation and property assignment and find an associated BidInstance toBooking.BidInstance = bid; i have checked and the bid is not null. finally i get the user extension file from the Current IPRINCIPAL USER as below UserExtension loggedInUser = m_BookingRepository.GetBookingCurrentUser(User); toBooking.UserExtension = loggedInUser; The Code to do the getUserExtension is : public UserExtension GetBookingCurrentUser(IPrincipal currentUser) { var user = (from u in Context.aspnet_Users .Include("UserExtension") where u.UserName == currentUser.Identity.Name select u).FirstOrDefault(); if (user != null) { var userextension = (from u in Context.UserExtension.Include("aspnet_Users") where u.aspnet_Users.UserId == user.UserId select u).FirstOrDefault(); return userextension; } else{ return null; } } It returns the userextension fine and assigns it fine. i originally used the aspnet_users but encountered this problem so tried to change it to the extension entity. as soon as i call the : Context.AddToBooking(booking); Context.SaveChanges(); i get the following exception and im completely baffled by how to fix it Entities in 'FutureFlyersEntityModel.Booking' participate in the 'FK_Booking_UserExtension' relationship. 0 related 'UserExtension' were found. 1 'UserExtension' is expected. then the final error that comes to the front end is: Metadata information for the relationship 'FutureFlyersModel.FK_Booking_BidInstance' could not be retrieved. Make sure that the EdmRelationshipAttribute for the relationship has been defined in the assembly. Parameter name: relationshipName.. But both the related entities are set in the booking entity passed thruogh PLEASE HELP Im at wits end with this

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• Linq to find pair of points with longest length?

  - by Chris

  I have the following code: foreach (Tuple<Point, Point> pair in pointsCollection) { var points = new List<Point>() { pair.Value1, pair.Value2 }; } Within this foreach, I would like to be able to determine which pair of points has the most significant length between the coordinates for each point within the pair. So, let's say that points are made up of the following pairs: (1) var points = new List<Point>() { new Point(0,100), new Point(100,100) }; (2) var points = new List<Point>() { new Point(150,100), new Point(200,100) }; So I have two sets of pairs, mentioned above. They both will plot a horizontal line. I am interested in knowing what the best approach would be to find the pair of points that have the greatest distance between, them, whether it is vertically or horizontally. In the two examples above, the first pair of points has a difference of 100 between the X coordinate, so that would be the point with the most significant difference. But if I have a collection of pairs of points, where some points will plot a vertical line, some points will plot a horizontal line, what would be the best approach for retrieving the pair from the set of points whose difference, again vertically or horizontally, is the greatest among all of the points in the collection? Thanks! Chris

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• Java SortedMap to Scala TreeMap

  - by Dave

  I'm having trouble converting a java SortedMap into a scala TreeMap. The SortedMap comes from deserialization and needs to be converted into a scala structure before being used. Some background, for the curious, is that the serialized structure is written through XStream and on desializing I register a converter that says anything that can be assigned to SortedMap[Comparable[_],_] should be given to me. So my convert method gets called and is given an Object that I can safely cast because I know it's of type SortedMap[Comparable[_],_]. That's where it gets interesting. Here's some sample code that might help explain it. // a conversion from comparable to ordering scala> implicit def comparable2ordering[A <: Comparable[A]](x: A): Ordering[A] = new Ordering[A] { | def compare(x: A, y: A) = x.compareTo(y) | } comparable2ordering: [A <: java.lang.Comparable[A]](x: A)Ordering[A] // jm is how I see the map in the converter. Just as an object. I know the key // is of type Comparable[_] scala> val jm : Object = new java.util.TreeMap[Comparable[_], String]() jm: java.lang.Object = {} // It's safe to cast as the converter only gets called for SortedMap[Comparable[_],_] scala> val b = jm.asInstanceOf[java.util.SortedMap[Comparable[_],_]] b: java.util.SortedMap[java.lang.Comparable[_], _] = {} // Now I want to convert this to a tree map scala> collection.immutable.TreeMap() ++ (for(k <- b.keySet) yield { (k, b.get(k)) }) <console>:15: error: diverging implicit expansion for type Ordering[A] starting with method Tuple9 in object Ordering collection.immutable.TreeMap() ++ (for(k <- b.keySet) yield { (k, b.get(k)) })

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• fluent nHibernate mapping of subclassed structure

  - by Codezy

  I have a workflow class that has a collection of phases, each phase has a collection of tasks. You can design a workflow that will be used by many engagements. When used in engagement I want to be able to add properties to each class (workflow, phase, and task). For example a task in the designer does not have people assigned, but a task in an engagement would need extra properties like who is assigned to it. I have tried many different approaches using subclasses or interfaces but I just can't get it to map the way I want. Currently I have the engagement level versions as subclasses, but I can't get Engagement phases to map to engagement workflows. Public Class WorkflowMapping Inherits ClassMap(Of Workflow) Sub New() Id(Function(x As Workflow) x.Id).Column("Workflow_Id").GeneratedBy.Identity() Map(Function(x As Workflow) x.Description) Map(Function(x As Workflow) x.Generation) Map(Function(x As Workflow) x.IsActive) HasMany(Function(x As Workflow) x.Phases).Cascade.All() End Sub End Class Public Class EngagementWorkflowMapping Inherits SubclassMap(Of EngagementWorkflow) Sub New() Map(Function(x As EngagementWorkflow) x.ClientNo) Map(Function(x As EngagementWorkflow) x.EngagementNo) End Sub End Class How would you approach mapping this in fluent (or hbm) so that you could load just the workflow base class when designing the flow, or the engagement subclass versions of each when being used by an engagement?

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• Assigning a property across threads

  - by Mike

  I have set a property across threads before and I found this post http://stackoverflow.com/questions/142003/cross-thread-operation-not-valid-control-accessed-from-a-thread-other-than-the-t about getting a property. I think my issue with the code below is setting the variable to the collection is an object therefore on the heap and therefore is just creating a pointer to the same object So my question is besides creating a deep copy, or copying the collection into a different List object is there a better way to do the following to aviod the error during the for loop. Cross-thread operation not valid: Control 'lstProcessFiles' accessed from a thread other than the thread it was created on. Code: private void btnRunProcess_Click(object sender, EventArgs e) { richTextBox1.Clear(); BackgroundWorker bg = new BackgroundWorker(); bg.DoWork += new DoWorkEventHandler(bg_DoWork); bg.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bg_RunWorkerCompleted); bg.RunWorkerAsync(lstProcessFiles.SelectedItems); } void bg_DoWork(object sender, DoWorkEventArgs e) { WorkflowEngine engine = new WorkflowEngine(); ListBox.SelectedObjectCollection selectedCollection=null; if (lstProcessFiles.InvokeRequired) { // Try #1 selectedCollection = (ListBox.SelectedObjectCollection) this.Invoke(new GetSelectedItemsDelegate(GetSelectedItems), new object[] { lstProcessFiles }); // Try #2 //lstProcessFiles.Invoke( // new MethodInvoker(delegate { // selectedCollection = lstProcessFiles.SelectedItems; })); } else { selectedCollection = lstProcessFiles.SelectedItems; } // *********Same Error on this line******************** // Cross-thread operation not valid: Control 'lstProcessFiles' accessed // from a thread other than the thread it was created on. foreach (string l in selectedCollection) { if (engine.LoadProcessDocument(String.Format(@"C:\TestDirectory\{0}", l))) { try { engine.Run(); WriteStep(String.Format("Ran {0} Succussfully", l)); } catch { WriteStep(String.Format("{0} Failed", l)); } engine.PrintProcess(); WriteStep(String.Format("Rrinted {0} to debug", l)); } } } private delegate void WriteDelegate(string p); private delegate ListBox.SelectedObjectCollection GetSelectedItemsDelegate(ListBox list); private ListBox.SelectedObjectCollection GetSelectedItems(ListBox list) { return list.SelectedItems; }

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• Using PHP to store results of a post request

  - by Paul M

  Im currently working with an API which requires we send our collection details in xml to their server using a post request. Nothing major there but its not working, so I want to output the sent xml to a txt file so I can look at actually whats being sent!! Instead of posting to the API im posting to a document called target, but the xml its outputting its recording seems to be really wrong. Here is my target script, note that the posting script posts 3 items, so the file being written should have details of each post request one after the other. <?php error_reporting(E_ALL); ini_set('display_errors', 1); // get the request data... $payload = ''; $fp = fopen('php://input','r'); $output_file = fopen('output.txt', 'w'); while (!feof($fp)) { $payload .= fgets($fp); fwrite($output_file, $payload); } fclose($fp); fclose($output_file); ?> I also tried the following, but this just recorded the last post request so only 1 collection item was recorded in the txt file, instead of all 3 output_file = fopen('output.txt', 'w'); while (!feof($fp)) { $payload .= fgets($fp); } fwrite($output_file, $payload); fclose($fp); fclose($output_file); I know im missing something really obvious, but ive been looking at this all morning!

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• multiple keys and values with google-collections

  - by flash3000

  Hello, I would like use google-collection in order to save the following file in a Hash with multiple keys and values Key1_1, Key2_1, Key3_1, data1_1, 0, 0 Key1_2, Key2_2, Key3_2, data1_2, 0, 0 Key1_3, Key2_3, Key3_3, data1_3, 0, 0 Key1_4, Key2_4, Key3_4, data1_4, 0, 0 The first three columns are the different keys and the last two integer are the two different values. I have already prepare a code which spilt the lines in chunks. import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; public class HashMapKey { public static void main(String[] args) throws FileNotFoundException, IOException { String inputFile = "inputData.txt"; BufferedReader br = new BufferedReader(new FileReader(inputFile)); String strLine; while ((strLine = br.readLine()) != null) { String[] line = strLine.replaceAll(" ", "").trim().split(","); for (int i = 0; i < line.length; i++) { System.out.print("[" + line[i] + "]"); } System.out.println(); } } } Unfortunately, I do not know how to save these information in google-collection? Thank you in advance. Best regards,

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• Word 2007 COM - Can't directly access a page when word is set to invisible

  - by Robbie

  I'm using Word 2007 via COM from PHP 5.2 Apache 2.0 on a windows machine. The goal is to programmatically render jpeg thumbnails from each page in a Word document. The following code works correctly if you set $word-Visible to 1: try { $word = new COM('word.application'); $word->Visible = 0; $word->Documents->Open("C:\\test.doc"); echo "Number of pages: " . $word->ActiveDocument->ActiveWindow->ActivePane->Pages->Count() . "</br>"; $i = 1; foreach ($word->ActiveDocument->ActiveWindow->ActivePane->Pages as $page) { echo "Page number: $i </br>"; $i++; } //get the EMF image of the page $data = $word->ActiveDocument->ActiveWindow->ActivePane->Pages->Item(3)->EnhMetaFileBits; $word->ActiveDocument->Close(); $word->Quit(); } catch (Exception $e) { echo "Exception: " .$e->getMessage(); } The test document I'm using contains 35 pages. The code will display the correct number of pages but the for each loop only loops over 1 page. I can only directly access page 1 and 2 in the Pages-Item() collection. If I try to access another page I get the exception: "The requested member of the collection does not exist." If I set the $word-Visible property to 1 I do get all the pages in the foreach loop and I can access any page directly. Everything is working as expected if Word is set to be visible. Even stranger is the fact that if I set Word to be invisible and I don't have the foreach loop I can only access page 1 instead of page 1 and 2 if I do the for each loop. Any pointers on how I can access all the pages in the document and keeping word invisible?

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• Using Scala structural types with abstract types

  - by Joshua Hartman

  I'm trying to define a structural type defining anything that has an "add" method (for instance, a java collection or a java map). Using this, I want to define a few higher order functions that operate on a certain collection object GenericTypes { type GenericCollection[T] = { def add(value: T): java.lang.Boolean} } import GenericTypes._ trait HigherOrderFunctions[T, CollectionType[X] <: GenericCollection[X]] { def map[V](fn: (T) => V): CollectionType[V] .... } class RichJList[T](list: List[T]) extends HigherOrderFunctions[T, java.util.List] This does not compile with the following error error: Parameter type in structural refinement may not refer to abstract type defined outside that same refinement I tried removing the parameter on GenericCollection and putting it on the method: object GenericTypes { type GenericCollection = { def add[T](value: T): java.lang.Boolean} } import GenericTypes._ trait HigherOrderFunctions[T, CollectionType[X] <: GenericCollection] class RichJList[T](list: List[T]) extends HigherOrderFunctions[T, java.util.List] but I get another error: error: type arguments [T,java.util.List] do not conform to trait HigherOrderFunctions's type parameter bounds [T,CollectionType[X] <: org.scala_tools.javautils.j2s.GenericTypes.GenericCollection] Can anyone give me some advice on how to use structural typing with abstract typed parameters in Scala? Or how to achieve what I'm looking to accomplish? Thanks so much!

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• ASP.NET dynamically reassign controls in the control tree

  - by pbz

  Let's say I have a custom control that looks like this <cc:MyControl runat="server" ID="myc" LinkControlID="NewParent" /> and, on the same page: <asp:TextBox runat="server" ID="NewParent" /> What I would like to do is, from MyControl, change NewParent's parent so that it would be part of MyControl's Controls collection. When I try to do this, from OnInit, I get: The control collection cannot be modified during DataBind, Init, Load, PreRender or Unload phases. Which makes sense, but is there a way around this? I'm OK if NewParent remains the child of the Page as long as from MyControl I can somehow redirect the rendering to MyControl's control. Can this be done? Thanks. EDIT: To clarify here's a mockup of MyControl: public class MyControl : Panel { protected override void OnInit(System.EventArgs e) { base.OnInit(e); if (!String.IsNullOrEmpty(LinkControlID)) { Control link = Parent.FindControl(LinkControlID); if (link != null) { Controls.Add(link); } } } public string LinkControlID { get; set; } } This assumes that MyControl and LinkControlID are placed on the same level in the tree hierarchy, which is OK in my case.

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• Should I have different models and views for no user data than for some user data?

  - by Sam Holder

  I'm just starting to learn asp.net mvc and I'm not sure what the right thing to do is. I have a user and a user has a collection of (0 or more) reminders. I have a controller for the user which gets the reminders for the currently logged in user from a reminder service. It populates a model which holds some information about the user and the collection of reminders. My question is should I have 2 different views, one for when there are no reminders and one for when there are some reminders? Or should I have 1 view which checks the number of reminders and displays different things? Having one view seems wrong as then I end up with code in my view which says if (Model.Reminders.Count==0){//do something} else {do something else}, and having logic in the view feels wrong. But if I want to have 2 different views then I'd like to have some code like this in my controller: [Authorize] public ActionResult Index() { MembershipUser currentUser = m_membershipService.GetUser(); IList<Reminder> reminders = m_reminderRepository.GetReminders(currentUser); if (reminders.Count == 0) { var model = new EmptyReminderModel { Email = currentUser.Email, UserName = currentUser.UserName }; return View(model); } else { var model = new ReminderModel { Email = currentUser.Email, UserName = currentUser.UserName, Reminders = reminders }; return View(model); } but obviously this doesn't compile as the View can't take both different types. So if I'm going to do this should I return a specific named view from my controller, depending on the emptiness of the reminders, or should my Index() method redirect to other actions like so: [Authorize] public ActionResult Index() { MembershipUser currentUser = m_membershipService.GetUser(); IList<Reminder> reminders = m_reminderRepository.GetReminders(currentUser); if (reminders.Count == 0) { return RedirectToAction("ShowEmptyReminders"); } else { return RedirectToAction("ShowReminders"); } } which seems nicer but then I need to re-query the reminders for the current user in the ShowReminders action. Or should I be doing something else entirely?

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• stack overflow on XMLListCollection collectionEvent

  - by reidLinden

  I'm working on a Flex 3 project, and I'm using a pair of XMLListCollection(s) to manage a combobox and a data grid. The combobox piece is working perfectly. The XMLListCollection for this is static. The user picks an item, and, on "change", it fires off an addItem() to the second collection. The second collection's datagrid then displays the updated list, and all is well. The datagrid, however, is editable. A further complication is that I have another event handler bound to the second XMLLIstCollection's "change" event, and in that handler, I do make additional changes to the second list. This essentially causes an infinite loop (a stack overflow :D ), of the second lists "change" handler. I'm not really sure how to handle this. Searching has brought up an idea or two regarding AutoUpdate functionality, but I wasn't able to get much out of them. In particular, the behavior persists, executing the 'updates' as soon as I re-enable, so I imagine I may be doing it wrong. I want the update to run, in general, just not DURING that code block. Thanks for your help!

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• Sharepoint isn't accepting new Credentials initially when switching users.

  - by Tiziani

  Hi all, I have a standard website (one webapplication and one site collection) with some custom pages and webparts. The issue I'm having is that when I try to switch users, using the "Sign In As a Different User" and entering new credentials (even for another site collection admin account), IE tries the account three times, and then it presents a 401 Access Denied screen. After that, if I erase all the stuff of access denied page from the browser's url, I'm logged as the new account I just had entered and was not accepted. After researching for a while on google, I found a KB ( http://support.microsoft.com/kb/970814 ) that might relate, but just tested here and it didn't work at all. The modified method suggested by the KB is the following: function LoginAsAnother(url, bUseSource) { document.cookie="loginAsDifferentAttemptCount=0"; if (bUseSource=="1") { GoToPage(url); } else { //var ch=url.indexOf("?") =0 ? "&" : "?"; //url+=ch+"Source="+escapeProperly(window.location.href); //STSNavigate(url); document.execCommand("ClearAuthenticationCache"); } } But after making this change, it no longer asks for a new credential. Any ideas?

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• Binding a WPF ComboBox to a different ItemsSource within a ListBox DataTemplate

  - by tjans

  I have a ListBox that contains a textbox and a combobox in its datatemplate: <ListBox Height="147" Margin="158,29,170,0" Name="PitcherListBox" VerticalAlignment="Top" ItemsSource="{Binding SomeCollectionOfObjects}" Background="Black"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal"> <TextBox Text="{Binding Path=Name}" /> <ComboBox ItemsSource="{Binding LocalArrayOfIntsProperty}" /> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> I want to bind the listbox to a collection of objects (which I've done successfully), but I want the combobox in the above datatemplate to have its itemssource set to a local property on the window (array of ints). I still want the combobox to have a two-way bind between its selected item and a property on the collection of objects... I have the following in code: PitcherListBox.DataContext = this; Basically in the end, I want the combobox within the listbox to have a different itemssource than the listbox itself. I can't seem to figure out how to change the ComboBox's ItemsSource in XAML. Can someone provide me some feedback? Thanks!

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• Mapping self-table one-to-many using non-PK clolumns

  - by Harel Moshe

  Hey, i have a legacy DB to which a Person object is mapped, having a collection of family-members, like this: class Person { ... string Id; /* 9-digits string */ IList<Person> Family; ... } The PERSON table seems like: Id: CHAR(9), PK FamilyId: INT, NOT NULL and several other non-relevant columns. I'm trying to map the Family collection to the PERSON table using the FamilyId column, which is not the PK as mentioned above. So, i actually have a one-to-many which is self-table-referential. I'm getting an error saying 'Cast is not valid' when my mapping looks like this: ... <set name="Family" table="Person" lazy="false"> <key column="FamilyId" /> <one-to-many class="Person" /> </set> ... because obviously, the join NHibernate is trying to make is between the PK column, Id, and the 'secondary' column, FamilyId, instead of joining the FamilyId column to itself. Any ideas please?

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• Generics and collections ... struggling with an implementation

  - by mattruma

  I am trying to figure out a way to leverage generics so I can make the property Value be an actual type that initialized (not sure if this is the correct way of saying it) when my collection class is created. I would like to have the syntax be something like: var list = new ListItemCollection<Guid>(parameters would go here); I have the following class: [Serializable] public class ListItem { public object Value { get; set; } public string Text { get; set; } public object DataContext { get; set; } public Nullable<bool> Checked { get; set; } public ListItem() { this.Checked = false; } } I have the following collection: [Serializable] public class ListItemCollection : List<ListItem> { public ListItem this[object value] { get { foreach (var child in this) { if (child.Value.Equals(value)) return child; } return null; } } public bool Contains(object value) { foreach (var child in this) { if (child.Value.Equals(value)) return true; } return false; } public void Add(object value, string text) { this.Add(value, text, null); } public void Add(object value, string text, object dataContext) { var child = new ListItem(); child.Value = value; child.Text = text; child.DataContext = dataContext; this.Add(child); } public ListItemCollection() { } public ListItemCollection(IEnumerable items, string displayMember, string valueMember, bool showEmptyItem, string emptyItemText, object emptyItemValue) { if (showEmptyItem) { this.Add(emptyItemValue, emptyItemText); } foreach (object item in items) { object text = null; object value = null; text = item.GetType().GetProperty(displayMember).GetValue(item, null); value = item.GetType().GetProperty(valueMember).GetValue(item, null); // Add the item this.Add(value, text.ToString(), item); } } }

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• Is there any way to programitically change a Data/ItemTemplate in Silverlight?

  - by Kris Erickson

  So I have a Listbox, which is using an ItemTemplate to display an image. I want to be able to change the size of the displayed image in the ItemTemplate. Through databinding I can change the Width, but the only way I can see how to do this is to add a Property (Say, ImageSize) to the class I am binding to and then change every item in the colleciton to have a new ImageSize. Is there no way to access the property of an item in that Datatemplate? E.g. <navigation:Page.Resources> <DataTemplate x:Key="ListBoxItemTemplate"> <Viewbox Height="100" Width="100"> <Image Source="{Binding Image}"/> </Viewbox> </DataTemplate> </navigation:Page.Resources> <Grid> <ListBox ItemTemplate="{StaticResource ListBoxItemTemplate}" ItemSource="{Binding Collection}"/> </Grid> Is there anyway to set the Width and Height of the viewbox without binding a property to every element in the collection?

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• Generate number sequences with LINQ

  - by tanascius

  I try to write a LINQ statement which returns me all possible combinations of numbers (I need this for a test and I was inspired by this article of Eric Lippert). The method's prototype I call looks like: IEnumerable<Collection<int>> AllSequences( int start, int end, int size ); The rules are: all returned collections have a length of size number values within a collection have to increase every number between start and end should be used So calling the AllSequences( 1, 5, 3 ) should result in 10 collections, each of size 3: 1 2 3 1 2 4 1 2 5 1 3 4 1 3 5 1 4 5 2 3 4 2 3 5 2 4 5 3 4 5 Now, somehow I'd really like to see a pure LINQ solution. I am able to write a non LINQ solution on my own, so please put no effort into a solution without LINQ. My tries so far ended at a point where I have to join a number with the result of a recursive call of my method - something like: return from i in Enumerable.Range( start, end - size + 1 ) select BuildCollection(i, AllSequences( i, end, size -1)); But I can't manage it to implement BuildCollection() on a LINQ base - or even skip this method call. Can you help me here?

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• using indexer to retrieve Linq to SQL object from datastore

  - by fearofawhackplanet

  class UserDatastore : IUserDatastore { ... public IUser this[Guid userId] { get { User user = (from u in _dataContext.Users where u.Id == userId select u).FirstOrDefault(); return user; } } ... } One of the developers in our team is arguing that an indexer in the above situation is not appropriate and that a GetUser(Guid id) method should be prefered. The arguments being that: 1) We aren't indexing into an in-memory collection, the indexer is basically performing a hidden SQL query 2) Using a Guid in an indexer is bad (FxCop flagged this also) 3) Returning null from an indexer isn't normal behaviour 4) An API user generally wouldn't expect any of this behaviour I agree to an extent with (most of) these points. But I'm also inclined to argue that one of the characteristics of Linq is to abstract the database access to make it appear that you're simply working with a bunch of collections, even though the lazy evaluation paradigm means those collections aren't evaluated until you run a query over them. It doesn't seem inconsistent to me to access the datastore in the same manner as if it was a concrete in-memory collection here. Also bearing in mind this is an inherited codebase which uses this pattern extensively and consistently, is it worth the refactoring? I accept that it might have been better to use a Get method from the start, but I'm not yet convinced that it's completely incorrect to be using an indexer. I'd be interested to hear all opinions, thanks.

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• XML comments on delegate declared events

  - by Matt Whitfield

  I am visiting some old code, and there are quite a few events declared with delegates manually rather than using EventHandler<T>, like this: /// <summary> /// Delegate for event Added /// </summary> /// <param name="index">Index of the item</param> /// <param name="item">The item itself</param> public delegate void ItemAdded(int index, T item); /// <summary> /// Added is raised whenever an item is added to the collection /// </summary> public event ItemAdded Added; All well and good, until I come to use sandcastle to document the library, because it then can't find any XML comments for the private Added field that is generated by the event declaration. I want to try and sort that out, but what I would like to do is either: Get sandcastle to ignore the auto-generated private field without telling it to ignore all private fields entirely or Get XML comments generated for the private field Is there any way of achieving this without re-factoring the code to look like this: /// <summary> /// Delegate for event <see cref="Added"/> /// </summary> /// <param name="index">Index of the item</param> /// <param name="item">The item itself</param> public delegate void ItemAdded(int index, T item); /// <summary> /// Private storage for the event firing delegate for the <see cref="Added"/> event /// </summary> private ItemAdded _added; /// <summary> /// Added is raised whenever an item is added to the collection /// </summary> public event ItemAdded Added { add { _added += value; } remove { _added -= value; } }

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• Database access through collections

  - by Mike

  Hi All, I have an 3 tiered application where I need to get database results and populated the UI. I have a MessagesCollection class that deals with messages. I load my user from the database. On the instantiation of a user (ie. new User()), a MessageCollection Messages = new MessageCollection(this) is performed. Message collection accepts a user as a parameter. User user = user.LoadUser("bob"); I want to get the messages for Bob. user.Messages.GetUnreadMessages(); GetUnreadMessages calls my Business Data provider which in turn calls the data access layer. The Business data provider returns List. My question is - I am not sure what the best practice is here - If I have a collection of messages in an array inside the MessagesCollection class, I could implement ICollection to provide GetEnumerator() and ability to traverse the messages. But what happens if the messages change and the the user has old messages loaded? What about big message collections? What if my user had 10,000 unread messages? I don't think accessing the database and returning 10,000 Message objects would be efficient.

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• How to prevent Hibernate from nullifying relationship column during entity removal

  - by Grzegorz

  I have two entities, A and B. I need to easily retrieve entities A, joined with entities B on the condition of equal values of some column (some column from A equal to some column in B). Those columns are not primary or foreign keys, they contain same business data. I just need to have access from each instance of A to the collection of B's with the same value of this column. So I model it like this: class A { @OneToMany @JoinColumn(name="column_in_B", referencedColumnName="column_in_A") Collection<B> bs; This way, I can run queries like "select A join fetch a.bs b where b...." (Actually, the real relationship here is many-to-many. But when I use @ManyToMany, Hibernate forces me to use join table, which doesnt exist here. So I have to use @OneToMany as workaround). So far so good. The main problem is: whenever I delete an instance of A, hibernate calls "Update B set column_in_B = null", becuase it thinks the column_in_B is foreign key pointing at primary key in A (and because row in A is deleted, it tries to clean the foreign key in B). BUT the column_in_B IS NOT a foreign key, and can't be modified, because it causes data lost (and this column is NOT NULL anyway in my case, causing data integerity exception to be thrown). Plese help me with this. How to model such relationships with Hibernate? (I would call it "virtual relationships", or "secondary relationships" or so: as they are not based on foreign keys, they are just some shortcuts which allows for retrieving related objects and quering for them with HQL)

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• JPA @ManyToMany on only one side?

  - by Ethan Leroy

  I am trying to refresh the @ManyToMany relation but it gets cleared instead... My Project class looks like this: @Entity public class Project { ... @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER) @JoinTable(name = "PROJECT_USER", joinColumns = @JoinColumn(name = "PROJECT_ID", referencedColumnName = "ID"), inverseJoinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "ID")) private Collection<User> users; ... } But I don't have - and I don't want - the collection of Projects in the User entity. When I look at the generated database tables, they look good. They contain all columns and constraints (primary/foreign keys). But when I persist a Project that has a list of Users (and the users are still in the database), the mapping table doesn't get updated gets updated but when I refresh the project afterwards, the list of Users is cleared. For better understanding: Project project = ...; // new project with users that are available in the db System.out.println(project getUsers().size()); // prints 5 em.persist(project); System.out.println(project getUsers().size()); // prints 5 em.refresh(project); System.out.println(project getUsers().size()); // prints 0 So, how can I refresh the relation between User and Project?

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• Recommendations, Asp.Net ObjectDataSource bind result of webservice call

  - by DerDres

  I need recommendations on how to solve / structure a solution to the following problem. In an asp.net web application i'll have to visualise results returned from a web service call. Im planning to use a repeater server control and bind this with an objectdatasource. The service returns a result of the form: public class SearchResult : IExtensibleDataObject { [DataMember] public Guid SearchId { get; set; } [DataMember] public DateTime Timestamp { get; set; } [DataMember] public int Offset { get; set; } [DataMember] public int TotalResults { get; set; } [DataMember] public IList<ResultDocumentData> Documents { get; set; } It is the collection of Documents that I need to visualise with a repeater which will be associated with an ObjectDataSource. The datasource should work on the type ResultDocumentData; the collection property in the class SearchResult. I think I need to wrap the call to the webservice in a dataaccess layer class, that will have a getDocuments method returning an IList, that the ObjectDataSource can use as its SelectMethod. I think I could make this work, but I would like to know how to do it in an elegant way. Can you give me general recommendations and/or recommendations for the following: WebProject Folderstructure + naming Naming conventions for the name of the service wrapper class Creating the service reference

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