【发布时间】：2018-02-20 18:31:22
【问题描述】：
https://stackoverflow.com/a/36192552/9387175
在此答案中，用户建议可以使用 comboBoxAdaptor 将项目添加到组合框中，即使项目源中不存在该项目。事实上，我确实看到它在代码中工作，但我不知道为什么它拒绝显示。正常的组合框在下面的示例中正常工作，comboBoxAdaptor 不可见。我是否缺少样式或模板之类的东西？我似乎找不到合适的组合。
我的xml：
<Window x:Class="WpfApp1.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:adapters="clr-namespace:WpfApp1.Adapters"
mc:Ignorable="d"
Title="MainWindow"
Height="200"
Width="650">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="210" />
<ColumnDefinition Width="210" />
</Grid.ColumnDefinitions>
<adapters:ComboBoxAdaptor Grid.Column="0"
AllowNull="False"
Height="80"
ItemsSource="{Binding Path=DataEntries}"
SelectedItem="{Binding Path=DataEntry}">
<ComboBox Height="80" />
</adapters:ComboBoxAdaptor>
<ComboBox Grid.Column="1"
Height="80"
ItemsSource="{Binding Path=DataEntries}"
SelectedItem="{Binding Path=DataEntry}"
DisplayMemberPath="Name"
SelectedValuePath="Name" />
</Grid>
</Window>
我的代码：
using System.Collections.Generic;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
namespace WpfApp1
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
SampleViewModel vm = new SampleViewModel();
DataContext = vm;
}
}
public class SampleDataClass
{
public string Name { get; set; }
public SampleDataClass(string name)
{
Name = name;
}
}
public class SampleViewModel : INotifyPropertyChanged
{
private readonly IList<SampleDataClass> _dataEntries;
private string _dataEntry;
public event PropertyChangedEventHandler PropertyChanged;
public SampleViewModel()
{
IList<SampleDataClass> list = new List<SampleDataClass>();
list.Add(new SampleDataClass("tools"));
list.Add(new SampleDataClass("set"));
list.Add(new SampleDataClass("sort"));
list.Add(new SampleDataClass("flap"));
_dataEntries = list;
}
public IList<SampleDataClass> DataEntries
{
get { return _dataEntries; }
}
public string DataEntry
{
get
{
return _dataEntry;
}
set
{
if (_dataEntry == value) {return;}
_dataEntry = value;
OnPropertyChanged("DataEntry");
}
}
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
}
【问题讨论】：
-
尝试将 SelectedItem 更改为
SelectedItem="{Binding SelectedProposal.CategoryCode, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}}"您也需要实现 INotifyPropertyChanged。 -
@dev1998 绑定一切正常，我可以在调试和窥探时看到所有内容。我只是有一个空白的正方形可以直观地查看。