.NET Tutorials, Forums, Interview Questions And Answers
Welcome :Guest
Sign In
Win Surprise Gifts!!!

Top 5 Contributors of the Month
Gaurav Pal
Post New Web Links

TextBox shows "old" value after being Coerced when bound to a Dependency Property

Posted By:      Posted Date: October 11, 2010    Points: 0   Category :WPF



I am writing a WPF Custom Control.  I want to be able to limit the input for the DependancyProperty "Text".  I have the OnCoerce event handlers connected and this property is bound to the "Text" property on a TextBox in my content template as shown below:


Code Snippet

<TextBox Name="PART_txtEdit"

Background="{TemplateBinding Background}"

BorderBrush="{TemplateBinding BorderBrush}"

View Complete Post

More Related Resource Links

How to take value of bound field of grid in a variable or in a textbox.


How to take value of bound field of grid in a variable or in a textbox.

 I m using this code in .aspx page for grid.

<asp:GridView ID="Grd_Mprocess" runat="server" AutoGenerateColumns="False"

                      Width="100%" AllowPaging="True"


                      AllowSorting="True" PageSize="5"  >

                 <RowStyle CssClass="odd" />


<asp:BoundField HeaderText="DOC_TYPE_PK" DataField="DOC_TYPE_PK"  Visible="true" >


  <asp:TemplateField HeaderText="DOC TYPE ID" Visible="true">  &nbs

Changing a textbox's readonly property right before update on a gridview


I have a gridview with a date field. I don't want the user to be able to type in their own date and mess up the format so I made the property readonly. That date is then set by a point and click interface. This is all working fine but when the user clicks update this field doesn't update because it's readonly. If i turn readonly off it works so is there a way to turn off the readonly property right before submit?

TextBox shows binding source text when window load, so why not with the ComboBox?

How can I get a ComboBox to show the binding source value when my window opens?  I have been searching all day for a solution to this, but cannot find anything.  So I have created a sample project to demonstrate my problem.  Below is a Vehicle class, very simple, two members Category and Make.  Category is an enumeration, Make is a string. namespace ComboExample { public class Vehicle { // Constants and enumerations public enum eCategory { Road, Air, Sea } // Attributes public eCategory Category { get; set; } public String Make { get; set; } // Construction public Vehicle(eCategory Category, String strMake) { this.Category = Category; this.Make = strMake; } } } Here is the C# for the MainWindow.  A new Vehicle object is created as a member.  In the constructor I set a data-provider in the XAML to this Vehicle object.  There is a button event for showing the values of the controls and objects so I can check the binding. namespace ComboExample { // Interaction logic for MainWindow.xaml public partial class MainWindow : Window { // Attributes Vehicle m_Car = new Vehicle(Vehicle.eCategory.Road, "BMW"); // Construction public MainWindow() { InitializeComponent(); // link data-p

Textbox Text Property

I am new to VB and I have read that if I don't explicity cast variable types it will eat up performance. I have been casting certain objects, such as values from data readers, but I was wondering if the object has a property that says it is a string, like the textbox "Text" property, if I need to still cast that as a string.   Right now my code says "txtSearch.Text" but should I be using "txtSearch.Text.ToString()"?   Thanks in advance for the help!

Binding to Dependency property

Dear all I have the follwoing xaml code in my main window : <Label Content="{Binding PlayerCount}" DataContext="{Binding ScatterViewModels}" Grid.Row="2" HorizontalAlignment="Center" VerticalAlignment="Center" FontSize="20"/> Then I have a class which is the datacontext of my label and host a dependcy property PlayerCount which is set as follow:  PlayerCount = ((Player)svi.Tag).Count Doing so I cannot get the value in my label, anything wrong with the binding ? thnaks for help regards SergeYour knowledge is enhanced by that of others.

Custom Workflow Activity dependency property FieldNames

I have a custom actvity in VS2008. All is well until I added a new dependancy property like so: public static DependencyProperty EventLookupColumnNameProperty = DependencyProperty.Register("EventLookupColumnName",typeof(string),typeof(FTFSyncEventToAttachmentListItem)); public static DependencyProperty EventLookupColumnIDProperty = DependencyProperty.Register("EventLookupColumnID",typeof(string),typeof(FTFSyncEventToAttachmentListItem)); [Description("Event Lookup Column Name")][DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)][Browsable(true)][ValidationOption(ValidationOption.Required)]public string EventLookupColumnName{get { return ((string)(base.GetValue(EventLookupColumnNameProperty))); }set { base.SetValue(EventLookupColumnNameProperty, value); } [Description("Event Lookup Column ID")][ValidationOption(ValidationOption.Required)][Browsable(true)][DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]public int EventLookupColumnID{get { return ((int)(base.GetValue(EventLookupColumnIDProperty))); }set { base.SetValue(EventLookupColumnIDProperty, value); }}Then in the actions file:    <Action Name="FTF Sync Event To Attachment List Item"   ClassName="DP.Sharepoint.Workflow.FTFSyncEventToAttachmentListItem"   Assembly="DP.Sharepoint.Workflow, Version=, Cultur

class contains non-dependency-property data members that are DependencyObject objects, you must also


I was reading the article Freezable Objects Overviewand came acrosee the statement

"If  your class contains non-dependency-property data members that are DependencyObject objects, you must also call the OnFreezablePropertyChanged method each time you change on of their values, even if you're setting the member to null. "

I quite do not understand the part about non-dependency-property data members that are DependencyObject objects. Can some one explain exactly what this means? If a data member is derived from the DependencyObject  class how then can the data member be a non dependency property?

I am also trying to locate some source code / project that overrides the OnFreezablePropertyChanged method, and have yet to find any on the interenet.

If anyone know whe

Bind An Already Bound TextBox to ComboBox SelectedItem


Hey all,


If I have a TextBox that is already two-way bound to something, but I also want it so when a ComboBox SelectedItem changes, then the TextBox's Text property is set to the new SelectedItem.


Here's what I have so far, I added the comment where the TextBox is, which I would like to also be bound to the ComboBox below this.


        <ListView Grid.Row="2" 
             DataContext="{Binding ScriptParameters}"

Referencing a Dependency Property in XAML of parent UserControl where the property setter acceptable


I hope that title wasn't too confusing. I'm going to try my hardest to explain what I am trying to do.

I have a child UserControl and parent UserControl. The child UserControl has a Dependency Property that I want to set in my parent UserControl. I want to see the set operation change the child UserControl visually while I change the xaml in the parent UserControl. This setter needs to require that it's value is selected from a specific subset of a set of objects.

How do I accomplish this?

The only thing I can think to do is to specify the name of the object being selected and handle the actual selection of that object in the callback of the dependency property setter.


DataTrigger bound to a datebound property using a converter not working.


Hi all, this will sound like a simple problem but I am really stumped!

I'm trying to create a TextBlock with a style that collapses when the text is "" or null. So in the style there's a DataTrigger bound to Text using a Converter that provide a boolean test for "" or null.

The problem is that the triggers never seem to fire. Debugging the converter suggests it never gets used. The debug output also doesn't warn me of failed bindings so I have no idea what is going wrong!


			<GlacialControls:IsNullOrEmptyStringConverter x:Key="isNullOrEmptyStringConverter"/>
			<Style x:Key="Co

TextBox MaxLength Property not enforced for Tablet PC Input Panel using Writing Pad


I have developed a sizeable Wpf application to target the XP Tablet PC 2005, running on a UMPC. However I have hit a serious issue with the TextBox MaxLength property when using the Tablet Input panel to input hand writing recognition to my application.


When using keyboard or Input Panel text input, the MaxLength property is enforced as you might expect. However if the writing pad is used and the MaxLength is exceeded an Exception of type 'System.ExecutionEngineException' is thrown, and the application terminates.


Code Snippet

<TextBox Name="textBox1" MaxLength="25" />



I have built a simple test application to demonstrate that the problem is not isolated to my particular application.


I would be grateful i

Force update of bound combobox when validation changes bound source property


.NET 3.5SP1, VS 2008

I have inherited a system for maintenance and I'm working my way through defect reports.  Once such issue involves insuring a combobox value is reset to a known good value when a validation failure occurs.  The combobox is bound to a source property loaded which is initialized when the user selects a case for update.  According to this post it is an issue inside of WPF to ignore value changes when processing an update to the source (at least that's how I interpret the post).  Unfortunately for me, the UpdateSourceTrigger for a combobox is PropertyChanged, so the suggested approach does not fit my needs.  I tried it anyway, just to be certain.

I've created a test app which mimics the application design and exhibits the behavior I'm attempting to work around.  At this point, I'm at a loss how to proceed further.  I'm certain there's something I'm missing and would appreciate a nudge in the proper direction.

xaml window:

<Window x:Class="TestWpf.ComboTest

How to search a bound ListBox from a TextBox



I am just starting out with WPF and so please pardon me if I ask very ignorant questions but I'm finding WPF quite an up-hill struggle! 

I have created a fairly simple app that has a Listbox to the left that is bound to a DataTable to an OLEDB datasource. Above this Listbox there is a Textbox. What I am trying to do is use the Texbox as search/filter on the bound Listbox. Currently I can click inside the Listbox and start typing and it works perfectly well in finding the most appropriate Item with the IsTextSearchEnabled=True. I want to mimic this functionality but in the Textbox. Is this possible? Here is the xmal:

<Window x:Class="Test.WPF.BasicContactSearch1.ContactWindow"
    Title="Contact Window" Height="480" Width="640"
    xmlns:local="clr-namespace:Test.WPF.BasicContactSearch1" Loaded="Window_Loaded">
  <DockPanel Width="auto" Height="auto" Margin="8 8 8 8">
    <Border Height="56" HorizontalAlignment="Stretch" VerticalAlignment="Top" BorderThickness="1" CornerRadius="8" DockPanel.Dock="Top" Backgroun

How and When Dependency Properties are bound and evaluated?



I have a custom combo box control derived from existing WPF combo box. This custom combo has a DP called AssociatedEnum, once set it evaluates the enum menbers and adds them to Items collection.. However all this enumerating over available values, is done in Combo's loaded event Is it reasonable to assume that all the bindings on Dependency props will be set and evaluated to their initial values during the controls load event.

I am not very sure about this as i have seen some instances where the Binding is evaluated post load event, which defeats entire purpose of writing the selection in load event. My question should i go ahead and implement property changed handler for this dependency property??

Regards, v703218

link | edit |

When binding value to ImageUrl property of Image using XPath it shows code as html markup on fronten


I have a listview in which I want to show an image from an xmldatasource control.

The following works, and shows the value of thumb (in this case: 12_634232073402187500_whatever.jpg)

<asp:ListView ID="repLocationsToCompare" ItemPlaceholderID="itemsGoHere" runat="server">
            <%# XPath("thumb")%>
<asp:XmlDataSource EnableCaching="false" XPath="root/data/compare/locations/location" ID="XMLDSCompare" runat="server"></asp:XmlDataSource>

No problem there, BUT, when I use an imagecontrol:

<asp:ListView ID="repLocationsToCompare" ItemPlaceholderID="itemsGoHere" runat="server">
            <asp:Image ID="img" Visible='<%# XPath("thumb

TextBox MultiLine shows squigly lines?


Why does this url show squigly lines in firefox and how do I remove them?


List<> Shows Different Values entered in the textbox


Good Day All

i have 20 Textboxes i am not sure what did i touch by i normally dont play with VS Settings i dont understand. So those textbox are normally defined like this

<asp:TextBox ID="txtUnitLen20" onKeyUp="Jump()"   runat="server" 
TabIndex="19" AutoPostBack="True"></asp:TextBox>

and i am adding the value of a Textbox to a List<string>


but if the value that is entered is "1" , there i will get this as a Value hex like this

[0x00000001] = "1"

Please note that the Textbox gives me "1" but the List gives me those Numbers. I have attached a screenshot below


ASP.NetWindows Application  .NET Framework  C#  VB.Net  ADO.Net  
Sql Server  SharePoint  Silverlight  Others  All   

Hall of Fame    Twitter   Terms of Service    Privacy Policy    Contact Us    Archives   Tell A Friend