How to: Add Value Entered by User to LookUpEdit's Data Source

• Aug 01, 2019
• 4 minutes to read

Suppose a lookup editor displays a list of persons in the dropdown window. Dropdown rows are retrieved from a collection of a custom ContactList class. For this purpose, the RepositoryItemLookUpEditBase.DataSource property is set to an instance of the ContactList collection.

Each element in the collection represents an object of the Contact class.

The following LookUpEditBase.ProcessNewValue event handler adds new records to the data source. This occurs when the end-user enters a new name in the edit box that does not exist in the dropdown list and presses the Enter key. The entry is added by the Add method implemented in the ContactList class. The ProcessNewValueEventArgs.Handled parameter is set to true in order to force the editor to locate the newly inserted record after the event handler is performed.

Before inserting a new record, a message box is displayed and this allows the user to submit or discard the value. The following message box appears when a ‘Jack Cooper’ entry is entered:

After pressing the ‘Yes’ button, the new string is added to the list and the editor picks it up:

C#

using DevExpress.XtraEditors.Controls;

//ProcessNewValue event handler
private void LookUpEdit1_ProcessNewValue(object sender, ProcessNewValueEventArgs e) {
    if ((string)e.DisplayValue != String.Empty &&
        MessageBox.Show(this, "Add the '" + e.DisplayValue.ToString() + "' entry to the list?",
        "Confirm", MessageBoxButtons.YesNo) == DialogResult.Yes) {
        ((sender as LookUpEdit).Properties.DataSource as ContactList).Add(
          new Contact(e.DisplayValue.ToString()));
        e.Handled = true;
    }
}

private void Form1_Load(object sender, System.EventArgs e) {
    //create a contact list 
    ContactList cList = new ContactList();
    cList.Add(new Contact("John Doe"));
    cList.Add(new Contact("Sam Hill"));
    cList.Add(new Contact("Karen Holmes"));
    cList.Add(new Contact("Bobbie Valentine"));
    cList.Add(new Contact("Frank Frankson"));

    //bind the lookup editor to the list
    lookUpEdit1.Properties.DataSource = cList;
    lookUpEdit1.Properties.DisplayMember = "Name";
    lookUpEdit1.Properties.ValueMember = "ID";            
    // Add columns.
    // The ID column is populated 
    // via the GetNotInListValue event (not listed in the example).
    lookUpEdit1.Properties.Columns.Add(new LookUpColumnInfo("ID", "ID", 20));
    lookUpEdit1.Properties.Columns.Add(new LookUpColumnInfo("Name", "Name", 80));
    //enable text editing
    lookUpEdit1.Properties.TextEditStyle = TextEditStyles.Standard
}


public class ContactList : System.Collections.CollectionBase {
    public Contact this[int index] {
        get {return (Contact)(List[index]);}
        set {List[index] = value;}
    }

    public int Add(Contact value) {
        return List.Add(value);
    }
    //...
}


 public class Contact {
     private string name;
     public Contact(string _name) {
         name = _name;
     }

     public string Name
     {
         get { return name; }
         set { name = value; }
     }

     public string Id
     {
         get { return Id; }
         set { name = value; }
     }
 }

VB.NET

Imports DevExpress.XtraEditors.Controls

'ProcessNewValue event handler
Private Sub lookUpEdit1_ProcessNewValue(ByVal sender As Object, ByVal e As ProcessNewValueEventArgs)
    If CStr(e.DisplayValue) <> String.Empty AndAlso MessageBox.Show(Me, "Add the '" & e.DisplayValue.ToString() & "' entry to the list?", "Confirm", MessageBoxButtons.YesNo) = DialogResult.Yes Then
        TryCast((TryCast(sender, LookUpEdit)).Properties.DataSource, ContactList).Add(New Contact(e.DisplayValue.ToString()))
        e.Handled = True
    End If
End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) _
  Handles MyBase.Load
    'create a contact list 
    Dim cList As ContactList = New ContactList
    cList.Add(New Contact("John Doe"))
    cList.Add(New Contact("Sam Hill"))
    cList.Add(New Contact("Karen Holmes"))
    cList.Add(New Contact("Bobbie Valentine"))
    cList.Add(New Contact("Frank Frankson"))

    'bind the lookup editor to the list
    LookUpEdit1.Properties.DataSource = cList
    LookUpEdit1.Properties.DisplayMember = "Name"
    LookUpEdit1.Properties.ValueMember = "ID"
    ' Add columns.
    ' The ID column is populated 
    ' via the GetNotInListValue event (not listed in the example).
    LookUpEdit1.Properties.Columns.Add(New LookUpColumnInfo("ID", "ID", 20))
    LookUpEdit1.Properties.Columns.Add(New LookUpColumnInfo("Name", "Name", 80))
    'enable text editing
    LookUpEdit1.Properties.TextEditStyle = TextEditStyles.Standard
End Sub


Public Class ContactList
    Inherits System.Collections.CollectionBase

    Default Public Property Item(ByVal index As Integer) As Contact
        Get
            Return CType(List(index), Contact)
        End Get
        Set(ByVal Value As Contact)
            List(index) = Value
        End Set
    End Property

    Public Function Add(ByVal value As Contact) As Integer
        Return List.Add(value)
    End Function

    '...

End Class


 Public Class Contact

     Private name_Renamed As String
     Public Sub New(ByVal _name As String)
         name_Renamed = _name
     End Sub

     Public Property Name() As String
         Get
             Return name_Renamed
         End Get
         Set(ByVal value As String)
             name_Renamed = value
         End Set
     End Property

     Public Property Id() As String
         Get
             Return Id
         End Get
         Set(ByVal value As String)
             name_Renamed = value
         End Set
     End Property
 End Class