c# - Wpf binding collection property in UserControl (xaml) -


add collections of buttons in usercontrol (options). in xaml disigner displayed.

output when run application:

  • if options not initialized, error xamlobjectwriterexception: property collection "wpfappusercontrol.buttons"."options" (null).
  • if options = new list(), window without buttons

mainwindow.xaml

    <window x:class="wpfappusercontrol.mainwindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"         xmlns:local="clr-namespace:wpfappusercontrol"         mc:ignorable="d"         title="mainwindow" height="250" width="300">     <grid>         <local:buttons x:name="buttons"                          verticalalignment="center"                        horizontalalignment="center"                         horizontalcontentalignment="center">             <local:buttons.options>                 <button content="agudabi 1" height="20" margin="2" />                 <button content="agudabi 2" height="20" margin="2" />                 <button content="agudabi 3" height="20" margin="2" />             </local:buttons.options>         </local:buttons>     </grid> </window>

buttons.xaml

<usercontrol x:class="wpfappusercontrol.buttons"              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"               xmlns:d="http://schemas.microsoft.com/expression/blend/2008"               xmlns:local="clr-namespace:wpfappusercontrol"              mc:ignorable="d"               d:designheight="300" d:designwidth="300">     <grid>         <wrappanel x:name="internalcontainer"  orientation="horizontal" horizontalalignment="center"/>     </grid> </usercontrol>

buttons.xaml.cs

#region usings  using system.collections.generic; using system.collections.objectmodel; using system.componentmodel; using system.windows; using system.windows.controls;  #endregion  namespace wpfappusercontrol {     public partial class buttons : usercontrol     {         public buttons()         {             //options = new observablecollection<button>();             initializecomponent();         }          public observablecollection<button> options         {             { return (observablecollection<button>) getvalue(optionsproperty); }             set { setvalue(optionsproperty, value); }         }          public static readonly dependencyproperty optionsproperty =             dependencyproperty.register(nameof(options), typeof(observablecollection<button>), typeof(buttons),                                         new propertymetadata(/*new observablecollection<button>()*/, propertychangedcallback));          private static void propertychangedcallback(dependencyobject d, dependencypropertychangedeventargs e)         {             var obj = d buttons;              foreach (var button in obj.options)             {                 obj.internalcontainer.children.add(button);             }         }     } }

here example of should do.

instead of usercontrol collection property, use itemscontrol this:

<itemscontrol itemssource="{binding options}">     <itemscontrol.itemspanel>         <itemspaneltemplate>             <wrappanel/>         </itemspaneltemplate>     </itemscontrol.itemspanel>     <itemscontrol.itemtemplate>         <datatemplate>             <button content="{binding name}" command="{binding command}"                     height="20" margin="2"/>         </datatemplate>     </itemscontrol.itemtemplate> </itemscontrol>

then create view model collection of data items properties button content , command:

public class viewmodel {     public observablecollection<option> options { get; }         = new observablecollection<option>(); }  public class option {     public string name { get; set; }     public icommand command { get; set; } }

initialize shown below, icommand implementation ommited brevity. search web relaycommand implementation details.

public mainwindow() {     initializecomponent();      var vm = new viewmodel();     vm.options.add(new option { name = "agudabi 1" });     vm.options.add(new option { name = "agudabi 2" });     vm.options.add(new option { name = "agudabi 3" });      datacontext = vm; }

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