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• How to refer to object in JavaScript event handler?

  - by George Edison

  Note: This question uses jQuery but the question has nothing to do with jQuery! Okay so I have this object: var box = new BigBox(); This object has a method named Serialize(): box.AddToPage(); Here is the method AddToPage(): function AddToPage() { $('#some_item').html("<div id='box' onclick='this.OnClick()'></div>"); } The problem above is the this.OnClick() (which obviously does not work). I need the onclick handler to invoke a member of the BigBox class. How can I do this? How can an object refer to itself in an event handler?

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• databinding to self without code

  - by jcollum

  I'm building a UserControl in WPF. The control has two properties, Title and Description, that I'd like to bind to two textblocks. Seems real straightforward, and I got it working, but I'm curious about something. To get it to work I had to add this code: void CommandBlock_Loaded(object sender, RoutedEventArgs e) { this.DataContext = this; } My bindings look like this: <TextBlock Text="{Binding Title}" Width="100" ... /> <TextBlock Text="{Binding Description}" Width="100" ... /> What I'm wondering is how come I couldn't get it to work without the this.DataContext = this; and instead use DataContext="{Binding RelativeSource={RelativeSource Self}}" (in the UserControl element of the markup)? I'm sure I'm missing something about DataContexts but don't know what.

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• How can I find out how much memory an object of a C++ class consumes?

  - by Shadow

  Hi, I am developing a Graph-class, based on boost-graph-library. A Graph-object contains a boost-graph, so to say an adjacency_list, and a map. When monitoring the total memory usage of my program, it consumes quite a lot (checked with pmap). Now, I would like to know, how much of the memory is exactly consumed by a filled object of this Graph-class? With filled I mean when the adjacency_list is full of vertices and edges. I found out, that using sizeof() doesn't bring me far. Using valgrind is also not an alternative as there is quite some memory allocation done previously and this makes the usage of valgrind impractical for this purpose. I'm also not interested in what other parts of the program cost in memory, I want to focus on one single object. Thank you.

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• Refresh UltraGrid's GroupBy Sort on child bands when ListChanged?

  - by Idriss

  I am using Infragistics 2009 vol 1. My UltraGrid is bound to a BindingList of business objects "A" having themself a BindingList property of business objects "B". It results in having two bands: one named "BindingList`1", the other one "ListOfB" thanks to the currency manager. I would like to refresh the GroupBy sort of the grid whenever a change is performed on the child band through the child business object and INotifyPropertyChange. If I group by a property in the child band which is a boolean (let's say "Active") and I subscribe to the event ListChanged on the bindinglist datasource with this event handler: void Grid_ListChanged(object sender, ListChangedEventArgs e) { if (e.ListChangedType == ListChangedType.ItemChanged) { string columnKey = e.PropertyDescriptor.Name; if (e.PropertyDescriptor.PropertyType.Name == "BindingList`1") { ultraGrid.DisplayLayout.Bands[columnKey].SortedColumns.RefreshSort(true); } else { UltraGridBand band = ultraGrid.DisplayLayout.Bands[0]; UltraGridColumn gc = band.Columns[columnKey]; if (gc.IsGroupByColumn || gc.SortIndicator != SortIndicator.None) { band.SortedColumns.RefreshSort(true); } ColumnFilter cf = band.ColumnFilters[columnKey]; if (cf.FilterConditions.Count > 0) { ultraGrid.DisplayLayout.RefreshFilters(); } } } } the band.SortedColumns.RefreshSort(true) is called but It gives unpredictable results in the groupby area when the property Active is changed in the child band: if one object out of three actives becomes inactive it goes from: Active : True (3 items) To: Active : False (3 items) Instead of (which is the case when I drag the column back and forth to the group by area) Active : False (1 item) Active : True (2 items) Am I doing something wrong? Is there a way to restore the expanded state of the rows when performing a RefreshSort(true); ?

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• WinForms data binding with a Save button?

  - by Mat

  How is data binding in C# WinForms supposed to work when you have a Save button? I don't want the data updated until I press Save! I have two forms (list and detail) backed by a BindingList<T> collection and my custom object from that collection, respectively. I can bind each form to the list or object appropriately. However, any changes made in the detail form are immediately reflected in the list form - I don't want to save the changes and update the details shown in the list until the Save button is pressed. Is data binding designed to support this? Is there a common pattern for doing so? Whichever way I look at it, binding doesn't seem to be able to support this scenario. I've considered the following: Pass a clone of the object to the detail form, but then I have to reconcile the changes on Save - changes may have been made to the copy in the list in the meantime. Implementing IEditableObject and calling EndEdit on save almost works as I can prevent the list being notified of the changes made until Save is pressed, but if something else causes a refresh the list is updated with the interim data. I'm currently left with dispensing with data binding in my detail view, and doing it all manually. Which is rather annoying.

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• DropDownListFor and relating my lambda to my ViewModel

  - by Daniel Harvey

  After googling for a while I'm still drawing a blank here. I'm trying to use a ViewModel to pull and provide a dictionary to a drop down list inside a strongly typed View: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="Notebook.ViewModels.CorporationJoinViewModel" %> ... <%: Html.DropDownListFor(c => c.CorpDictionary.Keys, new SelectList(Model.CorpDictionary, "Value", "Key"))%> I'm getting the error CS1061: 'object' does not contain a definition for 'CorpDictionary' and no extension method 'CorpDictionary' accepting a first argument of type 'object' could be found and the relevant bit of my ViewModel public class CorporationJoinViewModel { DB _db = new DB(); // data context public Dictionary<int, string> CorpDictionary { get { Dictionary<int, string> corporations = new Dictionary<int, string>(); int x = 0; foreach (Corporation corp in _db.Corporations) { corporations.Add(x, corp.name); } return corporations; } } I'll admit i have a pretty magical understanding of how linq is finding my ViewModel object from that lambda, and the error message is making me think it's not. Is my problem the method I'm using to pass the data? What am I missing here?

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• Binding search results to data grid

  - by Abid

  I want to add search functionality to my program. There's a class which has this function: public DataTable Search() { string SQL = "Select * from Customer where " + mField + " like '%" + mValue + "%'"; DataTable dt = new DataTable(); dt = dm.GetData(SQL); return (dt); } There are setter and getter properties for mField and mValue. DM is the object of class DataManagement, which has a method GetData: public DataTable GetData(string SQL) { SqlCommand command = new SqlCommand(); SqlDataAdapter dbAdapter = new SqlDataAdapter(); DataTable DataTable = new DataTable(); command.Connection = clsConnection.GetConnection(); command.CommandText = SQL; dbAdapter.SelectCommand = command; dbAdapter.Fill(DataTable); return (DataTable); } The search functionality is currently implemented like this: private void btnfind_Click(object sender, EventArgs e) { //cust is the object of class customer// if (tbCustName.Text != "") { cust.Field="CustName"; cust.Value = tbCustName.Text; } else if (tbAddress.Text != "") { cust.Value = tbAddress.Text; cust.Field="Address"; } else if (tbEmail.Text != "") { cust.Value = tbEmail.Text; cust.Field="Email"; } else if (tbCell.Text != "") { cust.Value = tbCell.Text; cust.Field = "Cell"; } DataTable dt = new DataTable(); dt = cust.Search(); dgCustomer.DataSource = dt; RefreshGrid(); } private void RefreshGrid() { DataTable dt = new DataTable(); dt = cust.GetCustomers(); dgCustomer.DataSource = dt; } This is not working. I don't know why. Please help.

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• Understanding UML composition better

  - by Prog

  The technical difference between Composition and Aggregation in UML (and sometimes in programming too) is that with Composition, the lifetime of the objects composing the composite (e.g. an engine and a steering wheel in a car) is dependent on the composite object. While with Aggregation, the lifetime of the objects making up the composite is independent of the composite. However I'm not sure about something related to composition in UML. Say ClassA is composed of an object of ClassB: class ClassA{ ClassB bInstance; public ClassA(){ bInstance = new ClassB(); } } This is an example of composition, because bInstance is dependent on the lifetime of it's enclosing object. However, regarding UML notation - I'm not sure if I would notate the relationship between ClassA and ClassB with a filled diamond (composition) or a white diamond (aggregation). This is because while the lifetime of some ClassB instances is dependent of ClassA instances - there could be ClassB instances anywhere else in the program - not only within ClassA instances. The question is: if ClassA objects are composed of ClassB objects - but other ClassB objects are free to be used anywhere else in the program: Should the relationship between ClassA and ClassB be notated as aggregation or as composition?

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• Formal definition for term "pure OO language"?

  - by Yauhen Yakimovich

  I can't think of a better place among SO siblings to pose such a question. Originally I wanted to ask "Is python a pure OO language?" but considering troubles and some sort of discomfort people experience while trying to define the term I decided to start with obtaining a clear definition for the term itself. It would be rather fair to start with correspondence by Dr. Alan Kay, who has coined the term (note the inspiration in biological analogy to cells or other living objects). There are following ways to approach the task: Give a comparative analysis by listing programming languages that exhibits certain properties unique and sufficient to define the term (although Smalltalk and Java are passing examples but IMO this way seems neither really complete or nor fruitful) Give a formal definition (or close to it, e.g. in more academic or mathematical style). Give a philosophical definition that would totally rely on semantical context of concrete language or a priori programming experience (there must be some chance of successful explanation by the community). My current version: "If a certain programing (formal) language that can (grammatically) differentiate between operations and operands as well as infer about the type of each operand whether this type is an object (in sense of OOP) or not then we call such a language an OO-language as long as there is at least one type in this language which is an object. Finally, if all types of the language are also objects we define such language to be pure OO-language." Would appreciate any possible improvement of it. As you can see I just made the definition dependent on the term "object" (often fully referenced as class of objects).

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• About shared (static) Members and its behavior

  - by Allende

  I just realized that I can access shared members from instances of classes (probably this is not correct, but compile and run), and also learn/discover that, I can modify shared members, then create a new instance and access the new value of the shared member. My question is, what happens to the shared members, when it comes back to the "default" value (class declaration), how dangerous is it do this ? is it totally bad ? is it valid in some cases ?. If you want to test my point here is the code (console project vb.net) that I used to test shared members, as you can see/compile/run, the shared member "x" of the class "Hello" has default value string "Default", but at runtime it changes it, and after creating a new object of that class, this object has the new value of the shared member. Module Module1 Public Class hello Public Shared x As String = "Default" Public Sub New() End Sub End Class Sub Main() Console.WriteLine("hello.x=" & hello.x) Dim obj As New hello() Console.WriteLine("obj.x=" & obj.x) obj.x = "Default shared memeber, modified in object" Console.WriteLine("obj.x=" & obj.x) hello.x = "Defaul shared member, modified in class" Console.WriteLine("hello.x=" & hello.x) Dim obj2 As New hello() Console.WriteLine("obj2.x=" & obj2.x) Console.ReadLine() End Sub End Module UPDATE: First at all, thanks to everyone, each answer give feedback, I suppose, by respect I should choose one as "the answer", I don't want to be offensive to anyone, so please don't take it so bad if I didn't choose you answer.

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• Empty interface to combine multiple interfaces

  - by user1109519

  Suppose you have two interfaces: interface Readable { public void read(); } interface Writable { public void write(); } In some cases the implementing objects can only support one of these but in a lot of cases the implementations will support both interfaces. The people who use the interfaces will have to do something like: // can't write to it without explicit casting Readable myObject = new MyObject(); // can't read from it without explicit casting Writable myObject = new MyObject(); // tight coupling to actual implementation MyObject myObject = new MyObject(); None of these options is terribly convenient, even more so when considering that you want this as a method parameter. One solution would be to declare a wrapping interface: interface TheWholeShabam extends Readable, Writable {} But this has one specific problem: all implementations that support both Readable and Writable have to implement TheWholeShabam if they want to be compatible with people using the interface. Even though it offers nothing apart from the guaranteed presence of both interfaces. Is there a clean solution to this problem or should I go for the wrapper interface? UPDATE It is in fact often necessary to have an object that is both readable and writable so simply seperating the concerns in the arguments is not always a clean solution. UPDATE2 (extracted as answer so it's easier to comment on) UPDATE3 Please beware that the primary usecase for this is not streams (although they too must be supported). Streams make a very specific distinction between input and output and there is a clear separation of responsibilities. Rather, think of something like a bytebuffer where you need one object you can write to and read from, one object that has a very specific state attached to it. These objects exist because they are very useful for some things like asynchronous I/O, encodings,...

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• Functional programming compared to OOP with classes

  - by luckysmack

  I have been interested in some of the concepts of functional programming lately. I have used OOP for some time now. I can see how I would build a fairly complex app in OOP. Each object would know how to do things that object does. Or anything it's parents class does as well. So I can simply tell Person().speak() to make the person talk. But how do I do similar things in functional programming? I see how functions are first class items. But that function only does one specific thing. Would I simply have a say() method floating around and call it with an equivalent of Person() argument so I know what kind of thing is saying something? So I can see the simple things, just how would I do the comparable of OOP and objects in functional programming, so I can modularize and organize my code base? For reference, my primary experience with OOP is Python, PHP, and some C#. The languages that I am looking at that have functional features are Scala and Haskell. Though I am leaning towards Scala. Basic Example (Python): Animal(object): def say(self, what): print(what) Dog(Animal): def say(self, what): super().say('dog barks: {0}'.format(what)) Cat(Animal): def say(self, what): super().say('cat meows: {0}'.format(what)) dog = Dog() cat = Cat() dog.say('ruff') cat.say('purr')

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• A few questions about how JavaScript works

  - by KayoticSully

  I originally posted on Stack Overflow and was told I might get some better answers here. I have been looking deeply into JavaScript lately to fully understand the language and have a few nagging questions that I can not seem to find answers to (Specifically dealing with Object Oriented programming. I know JavaScript is meant to be used in an OOP manner I just want to understand it for the sake of completeness). Assuming the following code: function TestObject() { this.fA = function() { // do stuff } this.fB = testB; function testB() { // do stuff } } TestObject.prototype = { fC : function { // do stuff } } What is the difference between functions fA and fB? Do they behave exactly the same in scope and potential ability? Is it just convention or is one way technically better or proper? If there is only ever going to be one instance of an object at any given time, would adding a function to the prototype such as fC even be worthwhile? Is there any benefit to doing so? Is the prototype only really useful when dealing with many instances of an object or inheritance? And what is technically the "proper" way to add methods to the prototype the way I have above or calling TestObject.prototype.functionName = function(){} every time? I am looking to keep my JavaScript code as clean and readable as possible but am also very interested in what the proper conventions for Objects are in the language. I come from a Java and PHP background and am trying to not make any assumptions about how JavaScript works since I know it is very different being prototype based. Also are there any definitive JavaScript style guides or documentation about how JavaScript operates at a low level? Thanks!

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• How would you model an objects representing different phases of an entity life cycle?

  - by Ophir Yoktan

  I believe the scenario is common mostly in business workflows - for example: loan management the process starts with a loan application, then there's the loan offer, the 'live' loan, and maybe also finished loans. all these objects are related, and share many fields all these objects have also many fields that are unique for each entity the variety of objects maybe large, and the transformation between the may not be linear (for example: a single loan application may end up as several loans of different types) How would you model this? some options: an entity for each type, each containing the relevant fields (possibly grouping related fields as sub entities) - leads to duplication of data. an entity for each object, but instead of duplicating data, each object has a reference to it's predecessor (the loan doesn't contain the loaner details, but a reference to the loan application) - this causes coupling between the object structure, and the way it was created. if we change the loan application, it shouldn't effect the structure of the loan entity. one large entity, with fields for the whole life cycle - this can create 'mega objects' with many fields. it also doesn't work well when there's a one to many or many to many relation between the phases.

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• LoginView inside FormView control is not databinding on PostBack

  - by subkamran

  I have a fairly simple form: <asp:FormView> <EditItemTemplate> <asp:LoginView> <RoleGroups> <asp:RoleGroup roles="Blah"> <ContentTemplate> <!-- Databound Controls using Bind/Eval --> </ContentTemplate> </asp:RoleGroup> </RoleGroups> </asp:LoginView> <!-- Databound Controls --> </EditItemTemplate> </asp:FormView> <asp:LinqDataSource OnUpdating="MyDataSource_Updating" /> I handle my LinqDataSource OnUpdating event and do some work handling some M:N fields. That all works. However, once the update is finished (and I call e.Cancel = true), the LoginView control does not databind its children... so they are all blank. The FormView's viewstate is still fine, as all the rest of the controls outside of the LoginView appear fine. I even handle the FormView_DataBound event and a Trace shows that the FormView is being databound on postback. Why then is the LoginView not keeping its ViewState/being databound? Here's a sample code snippet showing the flow: protected void MyDataSource_Updating(object s, LinqDataSourceUpdateEventArgs e) { try { Controller.DoSomething(newData); // attempts to databind again here fail // frmView.DataBind(); // MyDataSource.DataBind(); // LoginView.DataBind(); } catch { // blah } finally { e.Cancel = true; } }

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• ListBox Items Not Visible after DataBinding

  - by SidC

  Good Evening All, I am writing a page that allows users to search a parts table, select quantities and a listbox is to be populated with gridview values. Here's a snippet of my aspx page: <asp:ListBox runat="server" ID="lbItems" Width="155px"> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> <asp:ListItem></asp:ListItem> </asp:ListBox> Here's the relevant contents of codebehind: Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 'Define DataTable Columns as incoming gridview fields Dim dtSelParts As DataTable = New DataTable Dim dr As DataRow = dtSelParts.NewRow() dtSelParts.Columns.Add("PartNumber") dtSelParts.Columns.Add("NSN") dtSelParts.Columns.Add("PartName") dtSelParts.Columns.Add("Qty") 'Select those gridview rows that have txtQty <> 0 For Each row As GridViewRow In MySearch.Rows Dim textboxText As String = _ CType(row.FindControl("txtQty"), TextBox).Text If textboxText <> "0" Then 'Create the row dr = dtSelParts.NewRow() 'Fill the row with data dr("PartNumber") = MySearch.DataKeys(row.RowIndex)("PartNumber") dr("NSN") = MySearch.DataKeys(row.RowIndex)("NSN") dr("PartName") = MySearch.DataKeys(row.RowIndex)("PartName") 'Add the row to the table dtSelParts.Rows.Add(dr) End If Next 'Need to send items to Listbox control lbItems lbItems.DataSource = New DataView(dtSelParts) lbItems.DataValueField = "PartNumber" lbItems.DataValueField = "NSN" lbItems.DataValueField = "PartName" lbItems.DataBind() End Sub The page runs fine in that my search functiobnality is intact, and I can input quantity values into my gridview's textbox. When I click Add to Quote the Listbox receives focus, but no list items are visible. I've created several list items in the aspx page, however I don't know how to populate the contents of my datatable in the listbox. Can someone help a newbie with this, seemingly, easy issue? Thanks, Sid

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• Creating an object that is ready to be used & unset properties - with IoC

  - by GetFuzzy

  I have a question regarding the specifics of object creation and the usage of properties. A best practice is to put all the properties into a state such that the object is useful when its created. Object constructors help ensure that required dependencies are created. I've found myself following a pattern lately, and then questioning its appropriateness. The pattern looks like this... public class ThingProcesser { public List<Thing> CalculatedThings { get; set; } public ThingProcesser() { CalculatedThings = new List<Thing>(); } public double FindCertainThing() { CheckForException(); foreach (var thing in CalculatedThings) { //do some stuff with things... } } public double FindOtherThing() { CheckForException(); foreach (var thing in CalculatedThings) { //do some stuff with things... } } private void CheckForException() { if (CalculatedThings.Count < 2) throw new InvalidOperationException("Calculated things must have more than 2 items"); } } The list of items is not being changed, just looked through by the methods. There are several methods on the class, and to avoid having to pass the list of things to each function as a method parameter, I set it once on the class. While this works, does it violate the principle of least astonishment? Since starting to use IoC I find myself not sticking things into the constructor, to avoid having to use a factory pattern. For example, I can argue with myself and say well the ThingProcessor really needs a List to work, so the object should be constructed like this. public class ThingProcesser { public List<Thing> CalculatedThings { get; set; } public ThingProcesser(List<Thing> calculatedThings) { CalculatedThings = calculatedThings; } } However, if I did this, it would complicate things for IoC, and this scenario hardly seems appropriate for something like the factory pattern. So in summary, are there some good guidelines for when something should be part of the object state, vs. passed as a method parameter? When using IoC, is the factory pattern the best way to deal with objects that need created with state? If something has to be passed to multiple methods in a class, does that render it a good candidate to be part of the objects state?

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• MVVM/Presentation Model With WinForms

  - by Erik Ashepa

  Hi, I'm currently working on a brownfield application, it's written with winforms, as a preparation to use WPF in a later version, out team plans to at least use the MVVM/Presentation model, and bind it against winforms... I've explored the subject, including the posts in this site (which i love very much), when boiled down, the main advantage of wpf are : binding controls to properties in xaml. binding commands to command objects in the viewmodel. the first feature is easy to implement (in code), or with a generic control binder, which binds all the controls in the form. the second feature is a little harder to implement, but if you inherit from all your controls and add a command property (which is triggered by an internal event such as click), which is binded to a command instance in the ViewModel. The challenges I'm currently aware of are : implementing a commandmanager, (which will trigger the CanInvoke method of the commands as necessery. winforms only supports one level of databinding : datasource, datamember, wpf is much more flexible. am i missing any other major features that winforms lacks in comparison with wpf, when attempting to implement this design pattern? i sure many of you will recommend some sort of MVP pattern, but MVVM/Presentation model is the way to go for me, because I'll want future WPF support. Thanks in advance, Erik.

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• Binding a DropDownList in ListView InsertItemTemplate throwing an error

  - by Telos

  I've got a ListView which binds to a LinqDataSource and displays selected locations. The insert item Contains a dropdownlist that pulls from another LinqDataSource to give all the unselected locations. The problem is that I get the following error when loading the page: Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control. I'm doing a very similar setup in another page of the website, and it isn't giving us this error so I'm pretty confused. I know I can work around this by not binding, manually finding the control and getting the value, but this should work and I don't understand why it isn't. Any thoughts? The better part of the source code is below. <asp:LinqDataSource ID="ldsLocations" runat="server" ContextTypeName="ClearviewInterface.ESLinqDataContext" EnableDelete="true" EnableInsert="true" OnInserting="ldsLocations_Inserting" OnDeleting="ldsLocations_Deleting" TableName="crmLocations" OrderBy="addr1" OnSelecting="ldsLocations_Selecting" /> <asp:LinqDataSource ID="ldsFreeLocations" runat="server" ContextTypeName="ClearviewInterface.ESLinqDataContext" OrderBy="addr1" TableName="v_CVLocations" OnSelecting="ldsFreeLocations_Selecting" /> <asp:ListView ID="lvLocations" DataSourceID="ldsLocations" DataKeyNames="ID" InsertItemPosition="LastItem" runat="server" > <InsertItemTemplate> <tr> <td colspan="6"><hr /></td> </tr> <tr> <td colspan="2"> <asp:DropDownList ID="ddlFreeLocations" DataSourceID="ldsFreeLocations" DataTextField="addr1" DataValueField="record" MarkFirstMatch="true" SelectedValue='<%# Bind("record") %>' runat="server" /> </td> <td><asp:ImageButton ID="btnAdd" CommandName="Insert" SkinID="Insert" runat="server" /></td> </tr> </InsertItemTemplate>

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• Gridview buttonfield works LinkButton doesn't

  - by Karsten

  I've been fighting this problem for many hours now and could really use some help :-) This is the grid <asp:GridView ID="annonceView" runat="server" AutoGenerateColumns="False" DataKeyNames="Id" DataSourceID="dataSourceAnnoncer"> <Columns> <asp:BoundField DataField="Productname" HeaderText="Productname" /> <asp:buttonfield buttontype="Link" commandname="Delete" text="Delete"/> <asp:TemplateField HeaderText="Administration"> <ItemTemplate> <asp:LinkButton ID="lnkBtnDelete" runat="server" Text="Delete" CausesValidation="False" CommandName="Delete" OnClientClick="return confirm('Delete?')" /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> <asp:LinqDataSource ID="dataSourceAnnoncer" runat="server" ContextTypeName="Namespcae.TheContext" EnableDelete="True" TableName="Annoncer"> </asp:LinqDataSource> Clicking the buttonfield deletes the record just fine. Clicking the LinkButton doesn't work. I get a postback and the grid is shown as empty and no record is deleted. Seems like an empty databinding. I have tried to create a custom OnClick, OnCommand event for the LinkButton, but neither are fired. The OnRowCommand isn't fired either. I don't manually DataBind in the codebehind.

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• Swing data binding frameworks

  - by Ahe

  Hi Almost the same question has been asked a year ago, but the there has been some new development in this area. Selecting a (data binding) framework for swing application seems to be quite difficult. JSR-295 is abandoned, many swing frameworks which provide binding are work-in-progress, abandoned or too heavy for my quite simple app. JGoodies Swing suite is expensive, but luckily its libraries are free. Has anyone any real-world experience of new UFaceKit. It looks promising, but quite immature. I am particularly interested in Swing implementation and documentation. Any insight on UFaceKits development schedule would be appreciated, because I can hold by framework choice for a while. Requirements are not anything fancy, just working binding with a nice API. I also found Mogwai dataBinding, but it seems quite incomplete and requires manual synchronization activation, which makes it useless compared to coarse grained synchronization easily written by hand. Incomplete frameworks include at least Spring RCP and many JSR-296 forks. So, is the JGoodies data binding really the only realistic choice? Or are there any other viable solutions available?

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• WPF TexBox TwoWay Binding Problem when ValidationRules used

  - by ignis

  I seem to have a problem with TwoWay DataBinding - my application has a window with a bunch of textboxes that allow to edit values of the properties they are bound to. Everything works well except for textboxes that also have a validation rule defined, in which case no text is displayed in the textbox when the window opens (binding back-to-source still works fine for those). If I remove Validation rule, everything's back to normal. I searched for an answer to this for a few hours now, but somehow did not even find anyone else complaining of the same issue. I am completely new to WPF, and I am sure it is just a silly mistake I have somewhere in my code... I will greatly appreciate any feedback... <TextBox Margin="40,2,20,0" Grid.Column="0" Grid.Row="1" Background="#99FFFFFF" > <Binding Path="LastName" Mode="TwoWay" ValidatesOnDataErrors="true" UpdateSourceTrigger="LostFocus" > <Binding.ValidationRules> <validation:StringNameValidationRule /> </Binding.ValidationRules> </Binding> </TextBox>

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• How to implement Master-Detail with Multi-Selection in WPF?

  - by gehho

  Hi, I plan to create a typical Master-Detail scenario, i.e. a collection of items displayed in a ListView via DataBinding to an ICollectionView, and details about the selected item in a separate group of controls (TextBoxes, NumUpDowns...). No problem so far, actually I have already implemented a pretty similar scenario in an older project. However, it should be possible to select multiple items in the ListView and get the appropriate shared values displayed in the detail view. This means, if all selected items have the same value for a property, this value should be displayed in the detail view. If they do not share the same value, the corresponding control should provide some visual clue for the user indicating this, and no value should be displayed (or an "undefined" state in a CheckBox for example). Now, if the user edits the value, this change should be applied to all selected items. Further requirements are: MVVM compatibility (i.e. not too much code-behind) Extendability (new properties/types can be added later on) Does anyone have experience with such a scenario? Actually, I think this should be a very common scenario. However, I could not find any details on that topic anywhere. Thanks! gehho. PS: In the older project mentioned above, I had a solution using a subclass of the ViewModel which handles the special case of multi-selection. It checked all selected items for equality and returned the appropriate values. However, this approach had some drawbacks and somehow seemed like a hack because (besides other smelly things) it was necessary to break the synchronization between the ListView and the detail view and handle it manually.

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• When should I be cautious using about data binding in .NET?

  - by Ben McCormack

  I just started working on a small team of .NET programmers about a month ago and recently got in a discussion with our team lead regarding why we don't use databinding at all in our code. Every time we work with a data grid, we iterate through a data table and populate the grid row by row; the code usually looks something like this: Dim dt as DataTable = FuncLib.GetData("spGetTheData ...") Dim i As Integer For i = 0 To dt.Rows.Length - 1 '(not sure why we do not use a for each here)' gridRow = grid.Rows.Add() gridRow(constantProductID).Value = dt("ProductID").Value gridRow(constantProductDesc).Value = dt("ProductDescription").Value Next '(I am probably missing something in the code, but that is basically it)' Our team lead was saying that he got burned using data binding when working with Sheridan Grid controls, VB6, and ADO recordsets back in the nineties. He's not sure what the exact problem was, but he remembers that binding didn't work as expected and caused him some major problems. Since then, they haven't trusted data binding and load the data for all their controls by hand. The reason the conversation even came up was because I found data binding to be very simple and really liked separating the data presentation (in this case, the data grid) from the in-memory data source (in this case, the data table). "Loading" the data row by row into the grid seemed to break this distinction. I also observed that with the advent of XAML in WPF and Silverlight, data-binding seems like a must-have in order to be able to cleanly wire up a designer's XAML code with your data. When should I be cautious of using data-binding in .NET?

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• Visual Studio Designer looses / ignores data

  - by Kempeth

  I'm writing my own control - a datagridviewcolumn that displays integer values as texts like the comboboxcolumn can but without showing the combobox unless the cell is edited. I'm mostly there but I have problems with the databinding. I managed to get the necessary properties to appear in the designer but every time I set the datasource and close the editor the changes are dropped. When I assign the same datasource later in code it works like a charm, I just would prefer not having to do that... public class DataGridViewLookupColumn : DataGridViewColumn { private DataGridViewLookupCell template; private Object datasource = null; private String displaymember = String.Empty; private String valuemember = String.Empty; private BindingSource bindingsource = new BindingSource(); public DataGridViewLookupColumn() : base() { this.template = new DataGridViewLookupCell(); } public override DataGridViewCell CellTemplate { get { return this.template; } set { } } [Category("Data")] [ DefaultValue(null), RefreshProperties(RefreshProperties.Repaint), AttributeProvider(typeof(IListSource)), DesignerSerializationVisibility(DesignerSerializationVisibility.Visible), ] public object DataSource { get { return this.bindingsource.DataSource; //return this.datasource; } set { this.bindingsource.DataSource = value; this.bindingsource.EndEdit(); } } [Category("Data")] [ DefaultValue(""), TypeConverterAttribute("System.Windows.Forms.Design.DataMemberFieldConverter, System.Design"), Editor("System.Windows.Forms.Design.DataMemberFieldEditor, System.Design", typeof(System.Drawing.Design.UITypeEditor)), DesignerSerializationVisibility(DesignerSerializationVisibility.Visible), ] public String DisplayMember { get { return this.displaymember; } set { this.displaymember = value; } } [Category("Data")] [ DefaultValue(""), TypeConverterAttribute("System.Windows.Forms.Design.DataMemberFieldConverter, System.Design"), Editor("System.Windows.Forms.Design.DataMemberFieldEditor, System.Design", typeof(System.Drawing.Design.UITypeEditor)), DesignerSerializationVisibility(DesignerSerializationVisibility.Visible), ] public String ValueMember { get { return this.valuemember; } set { this.valuemember = value; } } } EDIT: I experimenting I just found out that that original DataGridViewComboBoxColumn can be made to behave exactly like I wanted to. By setting the DisplayStyle to Nothing the combobox control is only shown in edit mode.

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