在组合框中的DisplayMemberPath更新显示领域没有显示 [英] Update shown field in combobox DisplayMemberPath not shown

问题描述

我有一个WPF组合框。其的ItemsSource具有结合到ObservebaleCollection。所显示的值（通过的DisplayMemberPath）是实体类的名称属性。 问题是，当我更新当前选定的实体名称和消防NotifyPropertyChnage它不是在UI更新（即使如此，当我打开下拉列表是有更新）。 我想这个问题是，实体散列code仍然是相同的组合并没有看到有差别。我该怎么办？

XAML：

 ＆LT;组合框的ItemsSource ={结合的实体，模式=单向}
          的SelectedItem ={结合CurrentEntity}
          的DisplayMemberPath =名称/＆GT;
 

code：

 公共事件PropertyChangedEventHandler的PropertyChanged;

    的ObservableCollection＆LT;实体＆GT; m_entities =新的ObservableCollection＆LT;实体＆GT;（）;

    公众的ObservableCollection＆LT;实体＆GT;实体{{返回m_entities;}}

    公共实体CurrentEntity {获取;集}

    公共无效RenameEntity（字符串名称）
    {
    m_currentEntity.Name =名称;
    的PropertyChanged（这一点，新PropertyChangedEventArgs（CurrentEntity））;
    的PropertyChanged（这一点，新PropertyChangedEventArgs（实体））;
    }
 

解决方案

显然，这个问题是一个组合框调用数据对象的ToString显示所选项目和使用的DisplayMemberPath在下拉菜单项。

要解决这个问题，使用一个DataTemplate代替的DisplayMemberPath：

 ＆LT; D​​ataTemplate中X：关键=EntityTemplate
              数据类型={X：键入我：实体}＆GT;
    ＆LT; TextBlock的文本={结合名}/＆GT;
＆LT; / DataTemplate中＆GT;
 

并将其分配给组合框的ItemTemplate属性：

 ＆LT;组合框的ItemsSource ={结合实体}
          ItemTemplate中={的StaticResource EntityTemplate}
          的SelectedItem ={结合...}/＆GT;
 

I have a wpf combobox. Its ItemsSource has binding to an ObservebaleCollection. The shown value (via DisplayMemberPath) is the Name property of the Entity class. The problem is when I update the current selected entity name and fire NotifyPropertyChnage it is not updated in the UI (even so that when I open the combo list it is updated there). I guess the problem is that the entity hashcode is still the same and the combo doesn't see a difference. what can I do?

xaml:

<ComboBox     ItemsSource="{Binding Entities, Mode=OneWay}" 
          SelectedItem="{Binding CurrentEntity}"
          DisplayMemberPath="Name"/>

code:

    public event PropertyChangedEventHandler PropertyChanged;

    ObservableCollection<Entity> m_entities = new ObservableCollection<Entity>();

    public ObservableCollection<Entity> Entities{get{return m_entities;}} 

    public Entity CurrentEntity{get;set}

    public void RenameEntity(string name)
    {
    m_currentEntity.Name = name;
    PropertyChanged(this, new PropertyChangedEventArgs("CurrentEntity"));
    PropertyChanged(this, new PropertyChangedEventArgs("Entities"));
    }

解决方案

Apparently, the problem is that a combobox calls ToString on the data object to display the selected item and uses DisplayMemberPath for items in the drop-down.

To fix this, use a DataTemplate instead of DisplayMemberPath:

<DataTemplate x:Key="EntityTemplate"
              DataType="{x:Type my:Entity}">
    <TextBlock Text="{Binding Name}"/>
</DataTemplate>

And assign it to the combobox's ItemTemplate property:

<ComboBox ItemsSource="{Binding Entities}"
          ItemTemplate="{StaticResource EntityTemplate}"
          SelectedItem="{Binding ...}"/>

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