ListBox DataTemplate绑定问题 [英] ListBox DataTemplate Binding Issue

问题描述

您好，

我在为ListBox定义DataTemplate时遇到了一些问题。我是这样做的：

I'm experiencing some problem in defining a DataTemplate for my ListBox. Here is how I'm doing it:

<ListBox Grid.Row="1" Name="piecesListBox" >
      <ListBox.ItemTemplate>
        <DataTemplate>
          <DockPanel>
              <Viewbox Height="48" Width="48">
                <Canvas Height="{Binding ShapeWidth}" Width="{Binding ShapeLength}" VerticalAlignment="Center" HorizontalAlignment="Center">
                  <Canvas.Children>
                    <Path Stroke="Black" StrokeThickness="1">
                      <Path.Data>
                        <PathGeometry Figures="{Binding PieceShape}">
                        </PathGeometry>
                      </Path.Data>
                    </Path>
                  </Canvas.Children>
                </Canvas>
              </Viewbox>
          </DockPanel>
        </DataTemplate>
      </ListBox.ItemTemplate>

我在Visual Studio编辑器中的设计时遇到错误：在"DataTemplate"上抛出了NullReferenceException： Object 引用未设置为对象的实例。

I'm getting an error at design-time in the Visual Studio editor: NullReferenceException was thrown on "DataTemplate": Object reference not set to an instance of an object.

在运行时，一切正常。问题是我无法使用Visual Studio编辑器更改我的  ; UI。

At run-time, everything works fine. The problem is that I cannot use Visual Studio editor do change my UI.

如果我删除  数字 =" { 绑定
PieceShape }"  绑定，
然后我不敏感;没有任何错误。但这不是我需要的。

If I remove the Figures="{Binding PieceShape}" binding, then I don´t get any errors. But this is not what I need.

我对数据模板并不熟悉。我是否必须在XAML中实例化一个对象，以便编辑器能够在设计时加载ListBox？如果是这样，我该怎么办？一个简单的静态资源会有帮助吗？

I'm not much familiar with Data Templates. Do I have to instantiate an object in XAML so the editor can be able to load the ListBox in design time? If so, how can I do that? A simple Static Resource would help?

请注意，

Igor。

推荐答案

为了在设计时加载列表框数据，也许你可以使用ArrayList来创建一个集合数据对象在XAML中使用键或在XAML中使用键实例化集合对象，并将ListBox.ItemsSource引用到该键。

For loading listbox data in design time, perhaps you can use ArrayList to create a collection data object in XAML with a key or instantiate a collection object in XAML with a key, and reference ListBox.ItemsSource to that key.

示例：

< ; Window x：Class =" ListBoxBindingDesignTime.MainWindow"

        xmlns =" http://schemas.microsoft.com/winfx/2006/xaml/presentation "
$
        xmlns：x =" http://schemas.microsoft.com/winfx/2006/xaml "

        xmlns：coll =" clr-namespace：System.Collections; assembly = mscorlib"

        xmlns：local =" clr-namespace：ListBoxBindingDesignTime"
$
       标题= QUOT;主窗口"高度= QUOT; 350"宽度="525">

    < Window.Resources>

        < coll：ArrayList x：Key =" people">

            < local：Person Name =" Tom" />

            < local：Person Name =" Ken" />

            < local：Person Name =" Jen" />

        < / coll：ArrayList>

        < local：People x：Key =" peopleColl" />

    < /Window.Resources>

    < StackPanel>

        < ListBox ItemsSource =" {StaticResource people}" DisplayMemberPath =" Name" />

        < ListBox ItemsSource =" {StaticResource peopleColl}" DisplayMemberPath =" Name" />

    < / StackPanel>

< / Window>

<Window x:Class="ListBoxBindingDesignTime.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:coll="clr-namespace:System.Collections;assembly=mscorlib"
        xmlns:local="clr-namespace:ListBoxBindingDesignTime"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <coll:ArrayList x:Key="people">
            <local:Person Name="Tom"/>
            <local:Person Name="Ken"/>
            <local:Person Name="Jen"/>
        </coll:ArrayList>
        <local:People x:Key="peopleColl"/>
    </Window.Resources>
    <StackPanel>
        <ListBox ItemsSource="{StaticResource people}" DisplayMemberPath="Name"/>
        <ListBox ItemsSource="{StaticResource peopleColl}" DisplayMemberPath="Name"/>
    </StackPanel>
</Window>

使用System.Windows;

使用System.Collections.Generic;

using System.Windows;
using System.Collections.Generic;

命名空间ListBoxBindingDesignTime

{

    public partial class MainWindow：Window

    {

        public MainWindow（）

        {

            InitializeComponent（）;

        }
    }
   公共类人员：列表<人员>

    {

        public People（）

        {

           添加（新人{Name =" Person1"}）;

           添加（新人{Name =" Person2"}）;

           添加（新人{Name =" Person3"}）;

        }
    }
   公共级人员¥b $ b    {

        public string Name {set;得到; }
    }
}

namespace ListBoxBindingDesignTime
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }
    public class People : List<Person>
    {
        public People()
        {
            Add(new Person { Name = "Person1" });
            Add(new Person { Name = "Person2" });
            Add(new Person { Name = "Person3" });
        }
    }
    public class Person
    {
        public string Name { set; get; }
    }
}

这篇关于ListBox DataTemplate绑定问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！