根據(jù)您綁定的屬性，存在以下三種可能的情況：

• 常規(guī)綁定 - ViewModel屬性綁定到任何不可編輯的View元素屬性。由于該元素不可編輯，因此您無需將更新通知發(fā)送回綁定屬性（單向綁定）。
• 數(shù)據(jù)綁定 - Model屬性（數(shù)據(jù)字段）綁定到編輯器屬性。如果用戶可以更改編輯器值，則需要更新綁定屬性（雙向綁定）。
• 屬性依賴 - 來自同一個ViewModel的兩個屬性被綁定。

獲取工具下載 - DevExpress WinForm v21.2

綁定嵌套和非POCO視圖模型的屬性

如果您需要綁定嵌套的ViewModel屬性，請使用DevExpress.Mvvm.POCO.ViewModelSource.Create方法創(chuàng)建此嵌套ViewModel的實例，您可以通過父ViewModel訪問該實例，視圖綁定語法使用相同的SetBinding方法。

C#

//Nested ViewModel
public class NestedViewModel {
public virtual string Text { get; set; }
}

//Parent ViewModel
public class ViewModelWithChild {
public ViewModelWithChild() {
Child = ViewModelSource.Create<NestedViewModel>();
}
public NestedViewModel Child {
get;
private set;
}
}

//View code
var fluent = mvvmContext.OfType<ViewModelWithChild>();
fluent.SetBinding(editor, ed => ed.EditValue, x => x.Child.Text);

VB.NET

'Nested ViewModel
Public Class NestedViewModel
Public Overridable Property Text() As String
End Class

'Parent ViewModel
Public Class ViewModelWithChild
Public Sub New()
Child = ViewModelSource.Create(Of NestedViewModel)()
End Sub
Private privateChild As NestedViewModel
Public Property Child() As NestedViewModel
Get
Return privateChild
End Get
Private Set(ByVal value As NestedViewModel)
privateChild = value
End Set
End Property
End Class

'View code
Dim fluent = mvvmContext.OfType(Of ViewModelWithChild)()
fluent.SetBinding(editor, Function(ed) ed.EditValue, Function(x) x.Child.Text)

如果您不使用POCO模型，則框架不會自動發(fā)送更新通知。 要在這種情況下發(fā)送通知，請實現(xiàn)INotifyPropertyChanged接口或創(chuàng)建 - PropertyName-Changed 事件。請注意，您不能使用mvvmContext.ViewModelType屬性，您應(yīng)該調(diào)用mvvmContext.SetViewModel方法將ViewModel實例傳遞給組件。

C#

//ViewModel code
public class ObjectWithTextAndTitle {
string textCore;

public string Text {
get { return textCore; }
set {
if(textCore == value) return;
textCore = value;
OnTextChanged();
}
}
protected virtual void OnTextChanged() {
RaiseTextChanged();
}
protected void RaiseTextChanged() {
var handler = TextChanged;
if(handler != null) handler(this, EventArgs.Empty);
}
public event EventHandler TextChanged;
}

//View code
mvvmContext.SetViewModel(typeof(ObjectWithTextAndTitle), viewModelInstance);
var fluent = mvvmContext.OfType<ObjectWithTextAndTitle>();
fluent.SetBinding(editor, ed => ed.EditValue, x => x.Text);

VB.NET

'ViewModel code
Public Class ObjectWithTextAndTitle
Private textCore As String

Public Property Text() As String
Get
Return textCore
End Get
Set(ByVal value As String)
If textCore = value Then
Return
End If
textCore = value
OnTextChanged()
End Set
End Property
Protected Overridable Sub OnTextChanged()
RaiseTextChanged()
End Sub
Protected Sub RaiseTextChanged()
Dim handler = TextChangedEvent
If handler IsNot Nothing Then
handler(Me, EventArgs.Empty)
End If
End Sub
Public Event TextChanged As EventHandler
End Class

'View code
mvvmContext.SetViewModel(GetType(ObjectWithTextAndTitle), viewModelInstance)
Dim fluent = mvvmContext.OfType(Of ObjectWithTextAndTitle)()
fluent.SetBinding(editor, Function(ed) ed.EditValue, Function(x) x.Text)

數(shù)據(jù)綁定

要將編輯器綁定到模型屬性，請將BindingSource添加到視圖并使用標(biāo)準(zhǔn)DataBindings API。可選的 updateMode 參數(shù)允許您指定屬性是否在編輯器值更改時更新其值，以及（如果是）是應(yīng)該立即發(fā)生還是在驗證編輯器時發(fā)生。

C#

editor.DataBindings.Add(...);

VB.NET

editor.DataBindings.Add(...)

實體屬性綁定演示定義了一個自定義實體類，此類的實例用作數(shù)據(jù)記錄并具有 ID 和文本字段。 兩個數(shù)據(jù)字段都綁定到編輯器，BindingSource 組件存儲活動的實體對象。

C#

//View
mvvmContext.ViewModelType = typeof(ViewModel);
var fluentApi = mvvmContext.OfType<ViewModel>();
// Create a BindingSource and populate it with a data object.
//When a user modifies this object, the "Update" method is called
BindingSource entityBindingSource = new BindingSource();
entityBindingSource.DataSource = typeof(Entity);
fluentApi.SetObjectDataSourceBinding(entityBindingSource, x => x.Entity, x => x.Update());
// Data Bindings
idEditor.DataBindings.Add(
new Binding("EditValue", entityBindingSource, "ID"));
textEditor.DataBindings.Add(
new Binding("EditValue", entityBindingSource, "Text", true, DataSourceUpdateMode.OnPropertyChanged));

//ViewModel
public class ViewModel {
//...
public virtual Entity Entity {
get;
set;
}
//...
}

//Model
public class Entity {
public Entity(int id) {
this.ID = id;
this.Text = "Entity " + id.ToString();
}
public int ID { get; private set; }
public string Text { get; set; }
}

VB.NET

'View
mvvmContext.ViewModelType = GetType(ViewModel)
Dim fluentApi = mvvmContext.OfType(Of ViewModel)()
' Create a BindingSource and populate it with a data object.
'When a user modifies this object, the "Update" method is called
Dim entityBindingSource As New BindingSource()
entityBindingSource.DataSource = GetType(Entity)
fluentApi.SetObjectDataSourceBinding(entityBindingSource, Function(x) x.Entity, Function(x) x.Update())
' Data Bindings
idEditor.DataBindings.Add(New Binding("EditValue", entityBindingSource, "ID"))
textEditor.DataBindings.Add(New Binding("EditValue", entityBindingSource, "Text", True, DataSourceUpdateMode.OnPropertyChanged))

'ViewModel
Public Class ViewModel
'...
Public Overridable Property Entity() As Entity
'...
End Class

'Model
Public Class Entity
Public Sub New(ByVal id As Integer)
Me.ID = id
Me.Text = "Entity " & id.ToString()
End Sub
Private privateID As Integer
Public Property ID() As Integer
Get
Return privateID
End Get
Private Set(ByVal value As Integer)
privateID = value
End Set
End Property
Public Property Text() As String
End Class

DevExpress WinForm | 下載試用

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