wpf DataGrid 不使用 ObservableCollection 更新
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DataGrid does not updating with ObservableCollection
提问by kLeR1k
I'm trying to learn MVVM (Using MVVMLight Toolkit). But i'm stuck.
我正在尝试学习 MVVM（使用 MVVMLight 工具包）。但我被困住了。
In ViewModel have an ObservableCollection
在 ViewModel 中有一个 ObservableCollection
private ObservableCollection<Phone> _phoneNumbers;
public ObservableCollection<Phone> PhoneNumbers
{
get { return _phoneNumbers; }
private set
{
_phoneNumbers = value;
}
}
In ViewModel constructor fill it in such way PhoneNumbers = new ObservableCollection<Phone>(Guest.Person.Phones);
在 ViewModel 构造函数中以这种方式填充它 PhoneNumbers = new ObservableCollection<Phone>(Guest.Person.Phones);
In view have
鉴于有
<DataGrid x:Name="PhoneNumbersDataGrid" HorizontalAlignment="Left" Grid.Column="3" Grid.Row="11" VerticalAlignment="Top" Height="86" Width="auto" ItemsSource="{Binding PhoneNumbers, Mode=OneWay}" AutoGenerateColumns="False" IsReadOnly="True">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding PhoneNumber}" Header="Phone Number" IsReadOnly="True"/>
<DataGridTemplateColumn Header="Delete">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button Command="{Binding Guest.DeletePhoneCommand, Mode=OneWay, Source={StaticResource Locator}}">Delete</Button>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
In DeletePhoneCommand I'm trying to change PhoneNumberse.g.
在 DeletePhoneCommand 我试图改变PhoneNumbers例如
PhoneNumbers = new ObservableCollection<Phone>();
RaisePropertyChanged("PhoneNumbers");
Collection became empty but datagrid displays filled collection without any changes. "get" of Collection fires only when view is loading. Even when i RaisePropertyChanged("PhoneNumbers")it doesn't fire.
集合变为空，但数据网格显示已填充的集合而没有任何更改。只有在加载视图时才会触发 Collection 的“get”。即使我 RaisePropertyChanged("PhoneNumbers")不火。
What am I doing wrong?
我究竟做错了什么？
回答by Sajeetharan
If you want to notify the changes to your collection you should use Mode = TwoWay
如果你想通知你的收藏的变化，你应该使用 Mode = TwoWay
Two way will enable any change in object is reflected to the UI and any change in UI is reflected in the object.
两种方式将启用对象的任何更改反映到 UI 和 UI 的任何更改反映在对象中。
<DataGrid x:Name="PhoneNumbersDataGrid" HorizontalAlignment="Left" Grid.Column="3" Grid.Row="11" VerticalAlignment="Top" Height="86" Width="auto" ItemsSource="{Binding PhoneNumbers, Mode=TwoWay}" AutoGenerateColumns="False" IsReadOnly="True">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding PhoneNumber,Mode=TwoWay}" Header="Phone Number" IsReadOnly="True"/>
<DataGridTemplateColumn Header="Delete">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button Command="{Binding Guest.DeletePhoneCommand, Mode=OneWay, Source={StaticResource Locator}}">Delete</Button>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
回答by dnr3
If I'm not mistaken, the binding is broken when you reinitialize the collection. to fix this you will have to work on the already initialized collection. e.g :
如果我没记错的话，当您重新初始化集合时绑定会被破坏。要解决此问题，您必须处理已经初始化的集合。例如：
clear the list using the
使用
PhoneNumbers.Clear()
PhoneNumbers.Clear()
to add to the list, using
添加到列表中，使用
PhoneNumbers.Add(item)
PhoneNumbers.Add(item)
you don't need to raise the property changed event to update the list in the UI when you're using ObservableCollection. You will need it if you change a property of the item on the list.
当您使用 ObservableCollection 时，您不需要引发属性更改事件来更新 UI 中的列表。如果您更改列表中项目的属性，您将需要它。
回答by mohsen.asmand
at first clear the list with
首先清除列表
Clear()
then add item
然后添加项目
PhoneNumbers.Add(item)
