如何取消数据绑定更改？

Question

我有一个包含对象的 ListView。当用户选择要编辑的项目时，会打开一个表单，他可以在其中进行更改。目前，当用户在进行更改后关闭表单时，ListView 中的原始对象会更新，即使他没有单击“保存”就关闭了表单。当用户想要取消更改时，如何防止数据绑定？

---

<!--xaml-->
<TextBox x:Name="tbFirstName" Text="{Binding Path=MyObject.first_name}" />
<TextBox x:Name="tbLastName" Text="{Binding Path=MyObject.last_name}"  />

---

public class MyObject {
     public string FirstName {get; set;}
     public string LastName {get; set;}
}

List<MyObject> listOfObjects = new List<MyObject>(); 

---

//user selects what he wants to edit from a ListView and clicks the Edit button
//the object is passed to a new form where he can make the desired changes.
//the editing form is automatically populated with the object thanks to data binding! this is good! :)

---

//Edit Button Clicked:
EditorForm ef = new EditorForm(listOfObjects[listview.SelectedIndex]);
ef.ShowDialog();

---

private MyObject myObject;

public EditorForm(MyObject obj) {
    InitializeComponent();
    myObject = obj;
    DataContext = this;
}        

---

//user makes changes to FirstName
//user decides to cancel changes by closing form.
//>>> the object is still updated thanks to data-binding. this is bad. :(

Answer 1

更改 EditorForm 中的绑定以使用 UpdateSourceTrigger=Explicit。当您更改 UI 上的值时，这不会导致属性自动更新。相反，您必须以编程方式触发绑定以更新属性。

<!--xaml-->
<TextBox x:Name="tbFirstName" Text="{Binding Path=MyObject.first_name, UpdateSourceTrigger=Explicit}" />
<TextBox x:Name="tbLastName" Text="{Binding Path=MyObject.last_name, UpdateSourceTrigger=Explicit}"  />

当你的保存按钮被点击时，你需要从控件中获取绑定并触发更新：

var firstNameBinding = tbFirstName.GetBindingExpression(TextBox.TextProperty);
firstNameBinding.UpdateSource();
var lastNameBinding = tbLastName.GetBindingExpression(TextBox.TextProperty);
lastNameBinding.UpdateSource();