WPF:如何将对象绑定到ComboBox

Question

试图学习如何将对象绑定到各种类型的控件.在这个例子中,我想让我的对象中的示例数据出现在ComboBox中.代码运行,但出现的不是值(David,Helen,Joe)是文本"TheProtect.UserControls.Client")

XAML:(ucDataBindingObject.xaml)

<UserControl x:Class="TheProject.UserControls.ucDataBindingObject"
             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"
             Width="Auto"
             Height="Auto"
             mc:Ignorable="d">

    <Grid Width="130"
          Height="240"
          Margin="0">

            <ComboBox Width="310"
                      HorizontalAlignment="Left"
                      VerticalAlignment="Top"
                      ItemsSource="{Binding Path=Clients}" />
    </Grid>
</UserControl>

C#:ucDataBindingObject.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Controls;
namespace TheProject.UserControls
{
    public partial class ucDataBindingObject : UserControl
    {

        public List<Client> Clients { get; set; }


        public ucDataBindingObject()
        {
            Clients = new List<Client>();
            Clients.Add(new Client(1, "David")); // sample data
            Clients.Add(new Client(2, "Helen"));
            Clients.Add(new Client(3, "Joe"));


            InitializeComponent();
            this.DataContext = this;
        }
    }

C#Client.cs

using System;
using System.Linq;

namespace TheProject.UserControls
{
    public class Client
    {
        public int ID { get; set; }
        public string Name { get; set; }

        public Client(int id, string name)
        {
            this.ID = id;
            this.Name = name;
        }
    }
}

Answer 1

有几种方法可以告诉框架要显示的内容

1)DisplayMemberPath在ComboBox上使用(这将显示命名属性):

<ComboBox ItemsSource="{Binding Path=Clients}" 
          DisplayMemberPath="Name"
/>

2)ItemTemplate在ComboBox上设置.这类似于#1,除了允许您定义要显示的模板,而不仅仅是属性:

<ComboBox ItemsSource="{Binding Path=Clients}">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <Border BorderBrush="Green" BorderThickness="1" Padding="5">
                <TextBlock Text="{Binding Path=Name,StringFormat='Name: {0}'}" />
            </Border>
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>

3)ToString()向源类添加覆盖.如果您总是希望为给定的类显示相同的字符串,则非常有用.(请注意,默认ToString()值只是类类型名称,这就是您看到"TheProtect.UserControls.Client"的原因.)

public class Client
{
    // ...

    public override string ToString()
    {
        return string.Format("{0} ({1})", Name, ID);
    }
}

4)添加DataTemplate到XAML资源.这对于将给定的类类型与更复杂或风格化的模板相关联非常有用.

<UserControl xmlns:local="clr-namespace:TheProject.UserControls">
    <UserControl.Resources>
        <DataTemplate DataType="local:Client">
            <TextBlock Text="{Binding Name}" />
        </DataTemplate>
    </UserControl.Resources>

    // ...

</UserControl>    

Answer 2

在DisplayMemberPath,提供要在comboBox中显示的属性的名称.在SelectedValuePath,提供要选择的属性的名称.当你这样做时ComboBox.SelectedValue,你将获得这个属性的值.