BindableBase Class

A ViewModel that supports the INotifyPropertyChanged interface and allows you to use GetProperty and SetProperty methods to implement bindable properties.

Namespace: DevExpress.Mvvm

Assembly: DevExpress.WinUI.Mvvm.v23.2.dll

NuGet Package: DevExpress.WinUI

Declaration

C#

[DataContract]
public abstract class BindableBase :
    INotifyPropertyChanged

VB.NET

<DataContract>
Public MustInherit Class BindableBase
    Implements INotifyPropertyChanged

Remarks

Bindable Properties

The BindableBase class contains the protected GetValue and SetValue overloads that use the CallerMemberNameAttribute. You do not have to pass a property name to these methods as a parameter.

Run Demo: BindableBase Module in the WinUI MVVM Demo

To declare bindable properties, follow the steps below:

1. Inherit your ViewModel from the BindableBase class.
2. Define a property.
3. Use the GetValue and SetValue methods in the property’s get/set methods.

C#

using DevExpress.Mvvm;

public class ViewModel : BindableBase {
    public string FirstName { 
        get => GetValue<string>(); 
        set => SetValue(value); 
    }
}

VB.NET

Imports DevExpress.Mvvm

Public Class ViewModel
    Inherits BindableBase

    Public Property FirstName() As String
        Get
            Return GetValue(Of String)()
        End Get
        Set(ByVal value As String)
            SetValue(value)
        End Set
    End Property
End Class

When you assign a value to the property, the BindableBase class detects whether the property value is changed.

If the specified property’s value is changed, the SetValue method returns true. If the property’s new value is equal to the previous value, the method returns false.

C#

using DevExpress.Mvvm;

public class ViewModel : BindableBase {
    public string FirstName {
        get => GetValue<string>();
        set {
            if (SetValue(value))
                NotifyFullNameChanged();
        }
    }
}

VB.NET

Imports DevExpress.Mvvm

Public Class ViewModel
    Inherits BindableBase

    Public Property FirstName() As String
        Get
            Return GetValue(Of String)()
        End Get
        Set(ByVal value As String)
            If SetValue(value) Then
                NotifyFullNameChanged()
            End If
        End Set
    End Property
End Class

Run Custom Code When Property Value Is Changed

The SetValue method contains overloads that take a callback method as a parameter. When the property value is changed, the BindableBase class invokes this callback method.

C#

using DevExpress.Mvvm;

public class ViewModel : BindableBase {
    public string FirstName {
        get => GetValue<string>();
        set => SetValue(value, changedCallback: OnFirstNameChanged);
    }
    void OnFirstNameChanged() {
        //...
    }
}

VB.NET

Imports DevExpress.Mvvm

Public Class ViewModel
    Inherits BindableBase
    Public Property FirstName() As String
        Get
            Return GetValue(Of String)()
        End Get
        Set(ByVal value As String)
            SetValue(value, changedCallback:= AddressOf OnFirstNameChanged)
        End Set
    End Property
    Sub OnFirstNameChanged()
        '...
    End Sub
End Class

Raise the INotifyPropertyChanged.PropertyChanged Event

Call the RaisePropertyChanged/RaisePropertiesChanged methods to raise the PropertyChanged event for a specified property.

C#

using DevExpress.Mvvm;

public class ViewModel : BindableBase {
    public string FirstName {
        get => GetValue<string>();
        set => SetValue(value, changedCallback: NotifyFullNameChanged);
    }

    public string LastName {
        get => GetValue<string>();
        set => SetValue(value, changedCallback: NotifyFullNameChanged);
    }

    public string FullName => $"{FirstName} {LastName}";

    void NotifyFullNameChanged() {
        RaisePropertyChanged(nameof(FullName));
    }
}

VB.NET

Imports DevExpress.Mvvm

Public Class ViewModel
    Inherits BindableBase
    Public Property FirstName() As String
        Get
            Return GetValue(Of String)()
        End Get
        Set(ByVal value As String)
            SetValue(value, changedCallback:= AddressOf NotifyFullNameChanged)
        End Set
    End Property

    Public Property LastName() As String
        Get
            Return GetValue(Of String)()
        End Get
        Set(ByVal value As String)
            SetValue(value, changedCallback:= AddressOf NotifyFullNameChanged)
        End Set
    End Property

    Public ReadOnly Property FullName() As String
        Get
            Return FirstName & " " & LastName
        End Get
    End Property

    Private Sub NotifyFullNameChanged()
        RaisePropertyChanged(Function() FullName)
    End Sub
End Class

Use Properties With Backing Fields

An application stores its property values in Dictionaries. When you frequently access/update an application’s property values, the application performance may decrease. To bypass this performance issue, you can store property values in backing fields. The BindableBase class allows you to get and set values of properties that are stored in backing fields.

The following code sample stores values of FirstName and LastName properties in backing fields and calls the RaisePropertyChanged method when at least one of these property values is changed:

C#

using DevExpress.Mvvm;

public class ViewModel : BindableBase {
    string _FirstName;
    public string FirstName {
        get => _FirstName;
        set => SetValue(ref _FirstName, value, changedCallback: NotifyFullNameChanged);
    }

    string _LastName;
    public string LastName {
        get => _LastName;
        set => SetValue(ref _LastName, value, changedCallback: NotifyFullNameChanged);
    }
    public string FullName => $"{FirstName} {LastName}";

    void NotifyFullNameChanged() {
        RaisePropertyChanged(nameof(FullName));
    }
}

VB.NET

Imports DevExpress.Mvvm

Public Class ViewModel
    Inherits BindableBase

    Private _FirstName As String
    Public Property FirstName() As String
        Get
            Return _FirstName
        End Get
        Set(ByVal value As String)
            SetValue(_FirstName, value, changedCallback:= NotifyFullNameChanged)
        End Set
    End Property


    Private _LastName As String
    Public Property LastName() As String
        Get
            Return _LastName
        End Get
        Set(ByVal value As String)
            SetValue(_LastName, value, changedCallback:= NotifyFullNameChanged)
        End Set
    End Property

    Public ReadOnly Property FullName() As String
        Get
            Return FirstName & " " & LastName
        End Get
    End Property

    Private Sub NotifyFullNameChanged()
        RaisePropertyChanged(Function() FullName)
    End Sub
End Class

Inheritance

Show 14 items

Object

BindableBase

ViewModelBase

VirtualSourceBase

SchedulerCommands

TimeRulerCollection

DataControlCommandsBase

InfiniteAsyncSource

InfiniteSourceBase

DocumentViewerCommands

SchedulerViewCollection

GridControlCommands

DateTimeRangeCollection

TimeIndicatorCollection