WPF CheckBox双向绑定不起作用
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WPF CheckBox TwoWay Binding not working
提问by Matt
I have
我有
<DataGridCheckBoxColumn
Binding="{Binding Path=Foo, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
/>
And
和
public bool Foo{ get; set; }
Checking/Unchecking sets Foo, but setting Fooin code does not change the Checkbox state. Any Suggesitons?
Checking/Unchecking set Foo，但Foo在代码中设置不会改变 Checkbox 状态。任何建议？
回答by Andrew
You need to raise the PropertyChangedevent when you set Foo in your DataContext. Normally, it would look something like:
您需要提高PropertyChanged当您在设置富事件DataContext。通常，它看起来像：
public class ViewModel : INotifyPropertyChanged
{
private bool _foo;
public bool Foo
{
get { return _foo; }
set
{
_foo = value;
OnPropertyChanged("Foo");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected void OnPropertyChanged(string propertyName)
{
var propertyChanged = PropertyChanged;
if (propertyChanged != null)
{
propertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
If you call Foo = someNewvalue, the PropertyChangedevent will be raised and your UI should be updated
如果您调用Foo = someNewvalue，PropertyChanged将引发该事件并且您的 UI 应该更新
回答by pwrgreg007
I spent hours looking for a complete answer to this issue. I guess some people assume that other people searching this issue know the basics - sometimes we don't. A very important part about setting the form's data context was usually missing:
我花了几个小时寻找这个问题的完整答案。我猜有些人认为搜索此问题的其他人知道基础知识 - 有时我们不知道。通常缺少设置表单数据上下文的一个非常重要的部分：
public YourFormConstructor()
{
InitializeComponent();
DataContext = this; // <-- critical!!
}
My checkbox control was set up in the xaml file like this:
我的复选框控件是在 xaml 文件中设置的，如下所示：
<CheckBox x:Name="chkSelectAll" IsChecked="{Binding chkSelectAllProp, Mode=TwoWay}" HorizontalAlignment="Left"/>
The "Path=" and "UpdateSourceTrigger=..." parts appear to be optional, so I left them out.
“Path=”和“UpdateSourceTrigger=...”部分似乎是可选的，所以我将它们排除在外。
I am using this checkbox in a ListView header column. When someone checks or unchecks the checkbox, I want all the items in the ListView to also be checked or unchecked (select/unselect all functionality). I left that code in the example (as "optional logic") but your checkbox value logic (if any) would replace this.
我在 ListView 标题列中使用此复选框。当有人选中或取消选中复选框时，我希望 ListView 中的所有项目也被选中或取消选中（选择/取消选择所有功能）。我在示例中留下了该代码（作为“可选逻辑”），但您的复选框值逻辑（如果有）将替换它。
The ListView contents are set by browsing for a file, and when a new file is selected, code sets the ListView ItemsSource and the CheckBox is checked (selecting all the new ListView items), which is why this two-way operation is required. That portion of the code is not present in this example.
The ListView contents are set by browsing for a file, and when a new file is selected, code sets the ListView ItemsSource and the CheckBox is checked (selecting all the new ListView items), which is why this two-way operation is required. 此示例中不存在该部分代码。
The code in the xaml.cs file to handle the CheckBox looks like this:
xaml.cs 文件中用于处理 CheckBox 的代码如下所示：
// backing value
private bool chkSelectAllVal;
// property interchange
public bool chkSelectAllProp
{
get { return chkSelectAllVal; }
set
{
// if not changed, return
if (value == chkSelectAllVal)
{
return;
}
// optional logic
if (value)
{
listViewLocations.SelectAll();
}
else
{
listViewLocations.UnselectAll();
}
// end optional logic
// set backing value
chkSelectAllVal = value;
// notify control of change
OnPropertyChanged("chkSelectAllProp");
}
}
// object to handle raising event
public event PropertyChangedEventHandler PropertyChanged;
// Create the OnPropertyChanged method to raise the event
protected void OnPropertyChanged(string name)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
