LookUpEditBase.ProcessNewValue Event

Allows a new value entered into the edit box, to be added to the items source.

Assembly: DevExpress.Xpf.Core.v20.2.dll

NuGet Packages: DevExpress.WindowsDesktop.Wpf.Core, DevExpress.Wpf.Core

Declaration

C#
VB.NET

public event ProcessNewValueEventHandler ProcessNewValue

Public Event ProcessNewValue As ProcessNewValueEventHandler

Event Data

The ProcessNewValue event's data class is ProcessNewValueEventArgs. The following properties provide information specific to this event:

Property	Description
DisplayText	Gets the text entered by an end-user within the editor’s edit box.
Handled	Gets or sets a value that indicates the present state of the event handling for a routed event as it travels the route. Inherited from RoutedEventArgs.
OriginalSource	Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs.
PostponedValidation	Gets or sets whether to postpone edit value validation.
RoutedEvent	Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. Inherited from RoutedEventArgs.
Source	Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.

The event data class exposes the following methods:

Method	Description
InvokeEventHandler(Delegate, Object)	When overridden in a derived class, provides a way to invoke event handlers in a type-specific way, which can increase efficiency over the base implementation. Inherited from RoutedEventArgs.
OnSetSource(Object)	When overridden in a derived class, provides a notification callback entry point whenever the value of the Source property of an instance changes. Inherited from RoutedEventArgs.

Remarks

If the editor cannot find an item that matches the text entered by an end-user within the edit box (ProcessNewValueEventArgs.DisplayText), the ProcessNewValue event occurs. Handle this event to manually validate a new value, and if required, add the corresponding record to a data source.

The ProcessNewValue event is raised after a new value has been validated, allowing you to add this value to the items source. By default, the validation occurs while typing within the editor’s text box (see BaseEdit.ValidateOnTextInput). As a result, the ProcessNewValue event is fired each time a user presses a keyboard key.

The ProcessNewValue event occurs if an end-user presses the Enter key (the BaseEdit.ValidateOnEnterKeyPressed property should be set to true) or moves focus to another control.

If you add a new record, set the event parameter’s Handled property to true.

Note

If you want to show a floating container allowing an end-user to specify other values for a new record, set the event parameter’s ProcessNewValueEventArgs.PostponedValidation property to true. In this instance, a new value will be validated after a floating container is closed.

Example

This example shows how to manually initialize a new value and add it to a data source.

Update: Starting with version 13.1 of DevExpress controls, you can use the DevExpress MVVM Framework to accomplish this task. It is necessary to create a command in the view model (for instance, the ShowProductFormCommand command) and bind it with the LookUpEditBase.ProcessNewValue event via the trigger. This would allow you to display the dialog (UserControl1.xaml file) for editing new source items in the LookUpEdit control when this even is raised. Then, you can implement custom logic in the OnShowProductFormCommandExecute (ProductList.cs file) method to process values in this dialog. Please review our blogs to find additional information about DevExpress MVVM Framework:

View Example

<Application x:Class="HowToCreateLookUpEdit.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:HowToCreateLookUpEdit"
             xmlns:viewmodel="clr-namespace:HowToCreateLookUpEdit.ViewModel"
             StartupUri="MainWindow.xaml">
    <Application.Resources>
        <viewmodel:StringToIntConverter x:Key="converter" />
    </Application.Resources>
</Application>

Imports System
Imports System.Collections.Generic
Imports System.Collections.ObjectModel
Imports System.Linq
Imports System.Text
Imports System.Windows
Imports System.Windows.Data
Imports System.Windows.Input
Imports DevExpress.Xpf.Core
Imports DevExpress.Xpf.Editors
Imports DevExpress.Mvvm
Imports DevExpress.Mvvm.UI

Namespace HowToCreateLookUpEdit.ViewModel
    Public Class ProductListViewModel
        Inherits ViewModelBase


        Private products_Renamed As New ObservableCollection(Of Product)()
        Public ReadOnly Property Products() As ObservableCollection(Of Product)
            Get
                Return products_Renamed
            End Get
        End Property
        Public Sub New()
            MyBase.New()
            products_Renamed.Add(New Product() With {.ProductName = "Chang", .Country = "UK", .City = "Cowes", .UnitPrice = 19, .Quantity = 10, .ID = 1000})
            products_Renamed.Add(New Product() With {.ProductName = "Gravad lax", .Country = "Italy", .City = "Reggio Emilia", .UnitPrice = 12, .Quantity = 16, .ID = 1001})
            products_Renamed.Add(New Product() With {.ProductName = "Ravioli Angelo", .Country = "Brazil", .City = "Rio de Janeiro", .UnitPrice = 19, .Quantity = 12, .ID = 1002})
            products_Renamed.Add(New Product() With {.ProductName = "Tarte au sucre", .Country = "Germany", .City = "QUICK-Stop", .UnitPrice = 22, .Quantity = 50, .ID = 1003})
            products_Renamed.Add(New Product() With {.ProductName = "Steeleye Stout", .Country = "USA", .City = "Reggio Emilia", .UnitPrice = 18, .Quantity = 20, .ID = 1004})
            products_Renamed.Add(New Product() With {.ProductName = "Pavlova", .Country = "Austria", .City = "Graz", .UnitPrice = 21, .Quantity = 52, .ID = 1005})
            products_Renamed.Add(New Product() With {.ProductName = "Longlife Tofu", .Country = "USA", .City = "Boise", .UnitPrice = 7, .Quantity = 120, .ID = 1006})
            products_Renamed.Add(New Product() With {.ProductName = "Alice Mutton", .Country = "Mexico", .City = "México D.F.", .UnitPrice = 21, .Quantity = 15, .ID = 1007})
            products_Renamed.Add(New Product() With {.ProductName = "Alice Mutton", .Country = "Canada", .City = "Tsawwassen", .UnitPrice = 44, .Quantity = 16, .ID = 1008})
        End Sub

        Public _ShowProductFormCommand As ICommand

        Public ReadOnly Property ShowProductFormCommand() As ICommand
            Get
                If _ShowProductFormCommand Is Nothing Then
                    _ShowProductFormCommand = New DelegateCommand(Of String)(AddressOf OnShowProductFormCommandExecute)
                End If
                Return _ShowProductFormCommand
            End Get
        End Property

        Private ReadOnly Property DialogService() As IDialogService
            Get
                Return GetService(Of IDialogService)()
            End Get
        End Property

        Private Sub OnShowProductFormCommandExecute(ByVal parameter As String)
            If parameter = String.Empty Then
                Return
            End If
            Dim p As New Product() With {.ProductName = parameter}
            Dim addProductCommand As New UICommand() With {.Caption = "Add", .IsCancel = False, .IsDefault = True}

            Dim cancelProductCommand As New UICommand() With {.Caption = "Cancel", .IsDefault = False, .IsCancel = True}

            Dim result As UICommand = DialogService.ShowDialog(dialogCommands:= New List(Of UICommand)() From {addProductCommand, cancelProductCommand}, title:= "Add new row", viewModel:= p)

            If result Is addProductCommand Then
                products_Renamed.Add(p)
            End If
        End Sub
    End Class

    Public Class ProductListValueConverter
        Implements IEventArgsConverter

        Public Function Convert(ByVal sender As Object, ByVal args As Object) As Object Implements IEventArgsConverter.Convert
            Dim productName As String = DirectCast(args, ProcessNewValueEventArgs).DisplayText
            Return productName
        End Function
    End Class


    Public Class StringToIntConverter
        Implements IValueConverter

        #Region "IValueConverter Members"

        Public Function Convert(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements IValueConverter.Convert
            Return DirectCast(value, Integer)
        End Function

        Public Function ConvertBack(ByVal value As Object, ByVal targetType As System.Type, ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object Implements IValueConverter.ConvertBack
            Return value.ToString()
        End Function

        #End Region
    End Class
End Namespace

Imports System.Collections.Generic
Imports System.Collections.ObjectModel
Imports DevExpress.Mvvm

Namespace HowToCreateLookUpEdit.ViewModel
    Public Class Product
        Public Property ID() As Integer
        Public Property ProductName() As String
        Public Property Country() As String
        Public Property City() As String
        Public Property UnitPrice() As Integer
        Public Property Quantity() As Integer
    End Class
End Namespace

Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports DevExpress.Xpf.Core
Imports DevExpress.Xpf.Grid.LookUp
Imports HowToCreateLookUpEdit.ViewModel

Namespace HowToCreateLookUpEdit
    ''' <summary>
    ''' Interaction logic for MainWindow.xaml
    ''' </summary>
    Partial Public Class MainWindow
        Inherits Window

        Public Sub New()
            InitializeComponent()
        End Sub
    End Class
End Namespace

<Window x:Class="HowToCreateLookUpEdit.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
        xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors"
        xmlns:local="clr-namespace:HowToCreateLookUpEdit"
        xmlns:viewmodel="clr-namespace:HowToCreateLookUpEdit.ViewModel"
        xmlns:dxmvvm="http://schemas.devexpress.com/winfx/2008/xaml/mvvm"
        xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core">
    <Window.DataContext>
        <viewmodel:ProductListViewModel/>
    </Window.DataContext>
    <Grid>
        <dxg:LookUpEdit Name="lookUpEdit1" ItemsSource="{Binding Path=Products}"
                        HorizontalAlignment="Center" VerticalAlignment="Center"
                        Width="200"
                        DisplayMember="ProductName"
                        ValueMember="ID" 
                        AddNewButtonPlacement="EditBox"
                        AutoComplete="True"
                        IncrementalFiltering="True"
                        AutoPopulateColumns="True"
                        ImmediatePopup="True"
                        IsPopupAutoWidth="False">
            <dxmvvm:Interaction.Triggers>
                <dxmvvm:EventToCommand PassEventArgsToCommand="True" Command="{Binding ShowProductFormCommand}" EventName="ProcessNewValue" SourceName="lookUpEdit1">
                    <dxmvvm:EventToCommand.EventArgsConverter>
                        <viewmodel:ProductListValueConverter/>
                    </dxmvvm:EventToCommand.EventArgsConverter>
                </dxmvvm:EventToCommand>
            </dxmvvm:Interaction.Triggers>
        </dxg:LookUpEdit>               
    </Grid>
    <dxmvvm:Interaction.Behaviors>
        <dx:DialogService DialogWindowStartupLocation="CenterOwner">
            <dx:DialogService.ViewTemplate>
                <DataTemplate>
                    <local:UserControl1/>
                </DataTemplate>
            </dx:DialogService.ViewTemplate>
            <dx:DialogService.DialogStyle>
                <Style TargetType="dx:DXDialogWindow">
                    <Setter Property="Width" Value="345"/>
                    <Setter Property="Height" Value="324"/>
                </Style>
            </dx:DialogService.DialogStyle>
        </dx:DialogService>
    </dxmvvm:Interaction.Behaviors>
</Window>

<UserControl x:Class="HowToCreateLookUpEdit.UserControl1"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:HowToCreateLookUpEdit"
             xmlns:dxe="http://schemas.devexpress.com/winfx/2008/xaml/editors"
             xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core"
             xmlns:viewmodel="clr-namespace:HowToCreateLookUpEdit.ViewModel"      
             mc:Ignorable="d" d:DesignWidth="322" Height="324">    
    <Grid>
        <StackPanel Margin="8">
            <StackPanel HorizontalAlignment="Center" Orientation="Horizontal"
                            Margin="0,0,0,12">
                <TextBlock VerticalAlignment="Center" Text="Product Name:" Margin="0,0,4,0"/>
                <dxe:TextEdit VerticalAlignment="Center" IsReadOnly="True"
                                  EditValue="{Binding Path=ProductName, Mode=OneWay}"/>
            </StackPanel>
            <GroupBox Header="New Value Properties" Grid.Row="1" Grid.Column="1"
                               VerticalAlignment="Top" MinWidth="300">
                <Grid>
                    <Grid.ColumnDefinitions>
                        <ColumnDefinition/>
                        <ColumnDefinition/>
                    </Grid.ColumnDefinitions>
                    <Grid.RowDefinitions>
                        <RowDefinition/>
                        <RowDefinition/>
                        <RowDefinition/>
                        <RowDefinition/>
                        <RowDefinition/>
                    </Grid.RowDefinitions>
                    <TextBlock Text="Country:" VerticalAlignment="Center"
                                   Grid.Row="0" Grid.Column="0" Margin="0,0,6,4" />
                    <dxe:TextEdit x:Name="txtCountry" Grid.Row="0" Grid.Column="1"
                                      EditValue="{Binding Path=Country, Mode=TwoWay}" Margin="0,0,0,4"/>
                    <TextBlock Text="City:" VerticalAlignment="Center" Grid.Row="1"
                                   Grid.Column="0" Margin="0,0,6,4" />
                    <dxe:TextEdit x:Name="txtCity" Grid.Row="1" Grid.Column="1"
                                      EditValue="{Binding Path=City, Mode=TwoWay}" Margin="0,0,0,4"/>
                    <TextBlock Text="Quantity:" VerticalAlignment="Center" Grid.Row="2"
                                   Grid.Column="0" Margin="0,0,6,4" />
                    <dxe:TextEdit x:Name="txtQuantity" Grid.Row="2" Grid.Column="1"
                                      EditValue="{Binding Path=Quantity, Mode=TwoWay}" Margin="0,0,0,4"/>
                    <TextBlock Text="Unit Price:" VerticalAlignment="Center" Grid.Row="3"
                                   Grid.Column="0" Margin="0,0,6,4" />
                    <dxe:SpinEdit x:Name="spUnitPrice" Grid.Row="3" Grid.Column="1"
                                      EditValue="{Binding Path=UnitPrice, Mode=TwoWay, Converter={StaticResource converter}}" Margin="0,0,0,4"/>
                    <TextBlock Text="Product ID:" VerticalAlignment="Center" Grid.Row="4"
                                   Grid.Column="0" Margin="0,0,6,4" />
                    <dxe:SpinEdit x:Name="spId" Grid.Row="4" Grid.Column="1"
                                      EditValue="{Binding Path=ID, Mode=TwoWay, Converter={StaticResource converter}}" Margin="0,0,0,4"/>
                </Grid>
            </GroupBox>          
        </StackPanel>
    </Grid>
</UserControl>

Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Navigation
Imports System.Windows.Shapes

Namespace HowToCreateLookUpEdit
    ''' <summary>
    ''' Interaction logic for UserControl1.xaml
    ''' </summary>
    Partial Public Class UserControl1
        Inherits UserControl

        Public Sub New()
            InitializeComponent()
        End Sub
    End Class
End Namespace

Imports System
Imports System.Collections.Generic
Imports System.Configuration
Imports System.Data
Imports System.Linq
Imports System.Windows

Namespace HowToCreateLookUpEdit
    ''' <summary>
    ''' Interaction logic for App.xaml
    ''' </summary>
    Partial Public Class App
        Inherits Application

    End Class
End Namespace

using System.Collections.Generic;
using System.Collections.ObjectModel;
using DevExpress.Mvvm;

namespace HowToCreateLookUpEdit.ViewModel
{
    public class Product
    {
        public int ID { get; set; }
        public string ProductName { get; set; }
        public string Country { get; set; }
        public string City { get; set; }
        public int UnitPrice { get; set; }
        public int Quantity { get; set; }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace HowToCreateLookUpEdit
{
    /// <summary>
    /// Interaction logic for UserControl1.xaml
    /// </summary>
    public partial class UserControl1 : UserControl
    {
        public UserControl1()
        {
            InitializeComponent();            
        }
    }
}

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Data;
using System.Windows.Input;
using DevExpress.Xpf.Core;
using DevExpress.Xpf.Editors;
using DevExpress.Mvvm;
using DevExpress.Mvvm.UI;

namespace HowToCreateLookUpEdit.ViewModel {
    public class ProductListViewModel : ViewModelBase {
        ObservableCollection<Product> products = new ObservableCollection<Product>();
        public ObservableCollection<Product> Products { get { return products; } }
        public ProductListViewModel()
            : base() {
            products.Add(new Product() { ProductName = "Chang", Country = "UK", City = "Cowes", UnitPrice = 19, Quantity = 10, ID = 1000 });
            products.Add(new Product() { ProductName = "Gravad lax", Country = "Italy", City = "Reggio Emilia", UnitPrice = 12, Quantity = 16, ID = 1001 });
            products.Add(new Product() { ProductName = "Ravioli Angelo", Country = "Brazil", City = "Rio de Janeiro", UnitPrice = 19, Quantity = 12, ID = 1002 });
            products.Add(new Product() { ProductName = "Tarte au sucre", Country = "Germany", City = "QUICK-Stop", UnitPrice = 22, Quantity = 50, ID = 1003 });
            products.Add(new Product() { ProductName = "Steeleye Stout", Country = "USA", City = "Reggio Emilia", UnitPrice = 18, Quantity = 20, ID = 1004 });
            products.Add(new Product() { ProductName = "Pavlova", Country = "Austria", City = "Graz", UnitPrice = 21, Quantity = 52, ID = 1005 });
            products.Add(new Product() { ProductName = "Longlife Tofu", Country = "USA", City = "Boise", UnitPrice = 7, Quantity = 120, ID = 1006 });
            products.Add(new Product() { ProductName = "Alice Mutton", Country = "Mexico", City = "México D.F.", UnitPrice = 21, Quantity = 15, ID = 1007 });
            products.Add(new Product() { ProductName = "Alice Mutton", Country = "Canada", City = "Tsawwassen", UnitPrice = 44, Quantity = 16, ID = 1008 });
        }

        public ICommand _ShowProductFormCommand;

        public ICommand ShowProductFormCommand {
            get {
                if (_ShowProductFormCommand == null)
                    _ShowProductFormCommand = new DelegateCommand<string>(OnShowProductFormCommandExecute);
                return _ShowProductFormCommand;
            }
        }

        IDialogService DialogService { get { return GetService<IDialogService>(); } }

        private void OnShowProductFormCommandExecute(string parameter) {
            if (parameter == string.Empty) return;
            Product p = new Product() { ProductName = parameter };
            UICommand addProductCommand = new UICommand() {
                Caption = "Add",
                IsCancel = false,
                IsDefault = true
            };

            UICommand cancelProductCommand = new UICommand() {
                Caption = "Cancel",
                IsDefault = false,
                IsCancel = true
            };

            UICommand result = DialogService.ShowDialog(
                 dialogCommands: new List<UICommand>() { addProductCommand, cancelProductCommand },
                 title: "Add new row",
                 viewModel: p);

            if (result == addProductCommand) {
                products.Add(p);
            }
        }
    }

    public class ProductListValueConverter : IEventArgsConverter {
        public object Convert(object sender, object args) {
            string productName = ((ProcessNewValueEventArgs)args).DisplayText;
            return productName;
        }
    }


    public class StringToIntConverter : IValueConverter {
        #region IValueConverter Members

        public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture) {
            return (int)value;
        }

        public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture) {
            return value.ToString();
        }

        #endregion
    }
}

using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using DevExpress.Xpf.Core;
using DevExpress.Xpf.Grid.LookUp;
using HowToCreateLookUpEdit.ViewModel;

namespace HowToCreateLookUpEdit {
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window {                
        public MainWindow()
        {
            InitializeComponent();
        }
    }
}

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LookUpEditBase.ProcessNewValue Event

Declaration

Event Data

Remarks

Example