WebPropertyEditor Class

The base class for Property Editors that use controls inherited from a System.Web.UI.WebControls.WebControl.

Namespace: DevExpress.ExpressApp.Web.Editors

Assembly: DevExpress.ExpressApp.Web.v24.1.dll

NuGet Package: DevExpress.ExpressApp.Web

Declaration

C#
VB.NET

public abstract class WebPropertyEditor :
    PropertyEditor,
    ISupportViewEditMode,
    IAppearanceFormat,
    IAppearanceBase,
    ISupportToolTip,
    ISupportImmediatePostData

Public MustInherit Class WebPropertyEditor
    Inherits PropertyEditor
    Implements ISupportViewEditMode,
               IAppearanceFormat,
               IAppearanceBase,
               ISupportToolTip,
               ISupportImmediatePostData

The following members return WebPropertyEditor objects:

Remarks

Inherit the WebPropertyEditor class to implement a Property Editor using third-party or custom ASP.NET Web Forms controls. If you use DevExpress controls inherited from ASPxEditBase, use the ASPxPropertyEditor class instead.

In ASP.NET Web Forms XAF applications, Detail Views can be displayed in two modes - view (read only) and edit (editable). To support these modes, the WebPropertyEditor class introduces the following properties:

Member	Description
ViewEditMode	Specifies the current display mode of the Property Editor’s control.
Editor	Returns the Property Editor’s control used in edit mode.
InplaceViewModeEditor	Returns the Property Editor’s control used in view mode.

The WebPropertyEditor class implements the IAppearanceFormat interface to support conditional appearance rules.

Inherit WebPropertyEditor

Specify and Setup the Edit Mode Control

The CreateEditModeControlCore abstract method:

Instantiates the control to be used in the edit mode.
Performs the initial setup of the control.

Subscribes to control’s events that occur on a control value change. Each event handler calls the EditValueChangedHandler method. The EditValueChangedHandler method is the general-purpose handler for value-changed events. This method raises the ControlValueChanged event and calls the WriteValue() method.

C#
VB.NET

protected override WebControl CreateEditModeControlCore() {
    ASPxSpinEdit control = new ASPxSpinEdit();
    // Setup  the control:
    control.ValueChanged += EditValueChangedHandler;
    return control;
}

Protected Overrides Function CreateEditModeControlCore() As WebControl
    Dim control As New ASPxSpinEdit()
    ' Setup  the control:
    AddHandler control.ValueChanged, AddressOf EditValueChangedHandler
    Return control
End Function

The ReadEditModeValueCore abstract method passes the PropertyValue to the property of the Editor control specifying the displayed content (e.g., Text, Value, etc.).

C#
VB.NET

protected override void ReadEditModeValueCore() {
    ((ASPxSpinEdit)Editor).Value = PropertyValue;
}

Protected Overrides Sub ReadEditModeValueCore()
    CType(Editor, ASPxSpinEdit).Value = PropertyValue
End Sub

The GetControlValueCore abstract method returns the value specified by the WebPropertyEditor.Editor control used in the edit mode.

C#
VB.NET

protected override object GetControlValueCore() {
    return ((ASPxSpinEdit)Editor).Value;
}

Protected Overrides Function GetControlValueCore() As Object
    Return (CType(Editor, ASPxSpinEdit)).Value
End Function

Customize the View Mode Control (Optionally)

The System.Web.UI.WebControls.Label control is used in the view mode by default. Override these methods to customize the label’s string representation or to use another control.

Override The GetPropertyDisplayValue method to customize the string representation of the property value.

C#
VB.NET

protected override string GetPropertyDisplayValue() {
    string result = base.GetPropertyDisplayValue();
    if (string.IsNullOrEmpty(result)) result = "none";
    return result;
}

Protected Overrides Function GetPropertyDisplayValue() As String
    Dim result As String = MyBase.GetPropertyDisplayValue()
    If String.IsNullOrEmpty(result) Then
        result = "none"
    End If
    Return result
End Function

The CreateViewModeControlCore method instantiates and initializes the control used in the view mode.

C#
VB.NET

protected override WebControl CreateViewModeControlCore() {
    Label control = new Label();
    // Setup 'control' here.
    return control;
}

Protected Overrides Function CreateViewModeControlCore() As WebControl
    Dim control As New Label()
    ' Setup 'control' here.
    Return control
End Function

The ReadViewModeValueCore method passes the PropertyValue value to the property of the InplaceViewModeEditor control specifying the displayed content (e.g., Text, Value, etc.).

C#
VB.NET

protected override void ReadViewModeValueCore() {
    ((Label)InplaceViewModeEditor).Value = PropertyValue;
}

Protected Overrides Sub ReadViewModeValueCore()
    CType(InplaceViewModeEditor, Label).Value = PropertyValue
End Sub

Additional Customizations

The SetupControl method instantiates and initializes the control for which the customization code is provided. This method is called when the control is initialized (the Init event occurs).

C#
VB.NET

protected override void SetupControl(WebControl control) {
    base.SetupControl(control);
    if(ViewEditMode == ViewEditMode.Edit) {
        ASPxSpinEdit spinEdit = (ASPxSpinEdit)control;
        spinEdit.Width = Unit.Pixel(100);
    }
}

Protected Overrides Sub SetupControl(ByVal control As WebControl)
    MyBase.SetupControl(control)
    If ViewEditMode = ViewEditMode.Edit Then 
        Dim spinEdit As ASPxSpinEdit = CType(control, ASPxSpinEdit)
        spinEdit.Width = Unit.Pixel(100)
    End If 
End Sub

The BreakLinksToControl(Boolean) method disposes manually allocated resources and unsubscribes from control events.

C#
VB.NET

public override void BreakLinksToControl(bool unwireEventsOnly) {
    if(Editor != null) {
        ((ASPxSpinEdit)Editor).ValueChanged -= EditValueChangedHandler;
    }
    base.BreakLinksToControl(unwireEventsOnly);
}

Public Overrides Sub BreakLinksToControl(ByVal unwireEventsOnly As Boolean)
    If Editor IsNot Nothing Then
        RemoveHandler CType(Editor, ASPxSpinEdit).ValueChanged, AddressOf EditValueChangedHandler
    End If
    MyBase.BreakLinksToControl(unwireEventsOnly)
End Sub

The SetProcessValueChangedScript method registers a script passed to this method parameter to support the IModelOptionsWeb.ConfirmUnsavedChanges mode. The script is executed on the client side after the property value is changed by user. If you use any DevExpress web control, pass the script to the [EditClientSideEvents.ValueChanged]ValueChanged client-side event of the control’s ClientSideEvents object.
- C#
- VB.NET
```
protected override void SetProcessValueChangedScript(string script) {
    if (Editor != null) {
        ClientSideEventsHelper.AssignClientHandlerSafe((ASPxSpinEdit)Editor, "ValueChanged", script, Guid.NewGuid().ToString());
    }
}
```
```
Protected Overrides Sub SetProcessValueChangedScript(script As String)
    If Editor IsNot Nothing Then
        ClientSideEventsHelper.AssignClientHandlerSafe(CType(Editor, ASPxSpinEdit), "ValueChanged", script, Guid.NewGuid().ToString())
    End If
End Sub
```
If you use a custom third-party control, you should implement a code that provides the script execution when a user updates the editor value.
The SetImmediatePostDataScript method registers a script passed to this method parameter to support the ImmediatePostDataAttribute functionality (it is called only when ImmediatePostData is true). The script should be executed on the client side after the property value is changed by a user. If you use any DevExpress web control, pass the script to the ValueChanged client-side event of the control’s ClientSideEvents object.
- C#
- VB.NET
```
protected override void SetImmediatePostDataScript(string script) {
    ClientSideEventsHelper.AssignClientHandlerSafe((ASPxSpinEdit)Editor, "ValueChanged", script, Guid.NewGuid().ToString());
}
```
```
Protected Overrides Sub SetImmediatePostDataScript(ByVal script As String)
        ClientSideEventsHelper.AssignClientHandlerSafe(CType(Editor, ASPxSpinEdit), "ValueChanged", script, Guid.NewGuid().ToString())
End Sub
```
If you use a custom third-party control, you should implement a code that provides the script execution at the moment a user updates the editor value.

The ApplyReadOnly method assigns the AllowEdit value to the Enabled property of the Editor control used in the edit mode. You can apply extra customizations in this method.

C#
VB.NET

protected override void ApplyReadOnly() {
    base.ApplyReadOnly();
    if (!AllowEdit) {
        Editor.ToolTip = "You cannot change this value";
    }
    else {
        Editor.ToolTip = string.Empty;
    }
}

Protected Overrides Sub ApplyReadOnly()
    MyBase.ApplyReadOnly()
    If Not AllowEdit.ResultValue Then
        Editor.ToolTip = "You cannot change this value"
    Else
        Editor.ToolTip = String.Empty
    End If
End Sub

Important

A custom Property Editor that derives from the WebPropertyEditor should not throw exceptions. Exceptions thrown by such a Property Editor interrupt request processing. As a result, the application crashes.
The WebPropertyEditor‘s descendant should be public.
The WebPropertyEditor sets the ID value for the Editor and InplaceViewModeEditor controls. If you use a custom complex control with the inner controls hierarchy, set the ID for each inner control. For details, refer to the How to create controls dynamically article.