RepositoryItemCheckEdit.QueryValueByCheckState Event

Allows for custom conversion from the check state (checked, unchecked and indeterminate) to an edit value.

Namespace: DevExpress.XtraEditors.Repository

Assembly: DevExpress.XtraEditors.v24.1.dll

NuGet Package: DevExpress.Win.Navigation

Declaration

C#

[DXCategory("Events")]
public event QueryValueByCheckStateEventHandler QueryValueByCheckState

VB.NET

<DXCategory("Events")>
Public Event QueryValueByCheckState As QueryValueByCheckStateEventHandler

Event Data

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

Property	Description
CheckState	Gets the editor’s current check state.
Handled	Gets or sets whether the event is handled and no default processing is required. Inherited from QueryCheckStatesEventArgs.
Value	Use this property to set the edit value that corresponds to the current check state.

Remarks

The QueryValueByCheckState and RepositoryItemCheckEdit.QueryCheckStateByValue events allow you to manually convert from values to check states and vice versa.

See the RepositoryItemCheckEdit.QueryCheckStateByValue topic to learn more.

Example

This example demonstrates how to handle RepositoryItemCheckEdit.QueryCheckStateByValue and RepositoryItemCheckEdit.QueryValueByCheckState events in order to use a check editor to display and modify data from the bound data field.

The example assumes that a check editor is bound to a specific dataset field whose type is not obviously known and should be determined programmatically. The available data types that the field can take on are boolean, string and integer. So the field can contain the following combinations representing an option value (these values will be used to set the editor’s CheckEdit.EditValue property):

• True, False - for the boolean type;
• “Yes“, “No“, “?“ - for the string type;
• 1, 0, -1 - for the integer type.

It is evident that making use of RepositoryItemCheckEdit.ValueChecked, RepositoryItemCheckEdit.ValueUnchecked and RepositoryItemCheckEdit.ValueGrayed properties is insufficient in this case. Thus, the example requires and implements a custom “edit value -> check state” and “check state -> edit value” conversion logic, which is illustrated by the sample code below.

C#

using DevExpress.XtraEditors.Controls;

private void checkEdit1_QueryCheckStateByValue(object sender, QueryCheckStateByValueEventArgs e) {
    string val = e.Value.ToString();
    switch (val) {
        case "True":
        case "Yes":
        case "1":
            e.CheckState = CheckState.Checked;
            break;
        case "False":
        case "No":
        case "0":
            e.CheckState = CheckState.Unchecked;
            break;
        default:
            e.CheckState = CheckState.Indeterminate;
            break;
    }
    e.Handled = true;
}

private void checkEdit1_QueryValueByCheckState(object sender, QueryValueByCheckStateEventArgs e) {
    CheckEdit edit = sender as CheckEdit;
    object val = edit.EditValue;
    switch (e.CheckState) {
        case CheckState.Checked:
            if (val is bool) e.Value = true;
            else if (val is string) e.Value = "Yes";
            else if (val is int) e.Value = 1;
            else e.Value = null;
        break;
        case CheckState.Unchecked:
            if (val is bool) e.Value = false;
            else if (val is string) e.Value = "No";
            else if (val is int) e.Value = 0;
            else e.Value = null;
            break;
        default:
            if (val is bool) e.Value = false;
            else if (val is string) e.Value = "?";
            else if (val is int) e.Value = -1;
            else e.Value = null;
            break;
    }
    e.Handled = true;
}

VB.NET

Private Sub QueryCheckStateByValue(ByVal sender As Object, _
  ByVal e As DevExpress.XtraEditors.Controls.QueryCheckStateByValueEventArgs)
    Dim val As String = e.Value.ToString()
    Select Case val
        Case "True", "Yes", "1"
            e.CheckState = CheckState.Checked
        Case "False", "No", "0"
            e.CheckState = CheckState.Unchecked
        Case Else
            e.CheckState = CheckState.Indeterminate
    End Select
    e.Handled = True
End Sub

Private Sub QueryValueByCheckState(ByVal sender As Object, _ 
  ByVal e As DevExpress.XtraEditors.Controls.QueryValueByCheckStateEventArgs)
    Dim Edit As CheckEdit = CType(sender, CheckEdit)
    Dim Val As Object = Edit.EditValue
    Select Case e.CheckState
        Case CheckState.Checked
            If TypeOf Val Is Boolean Then
                e.Value = True
            ElseIf TypeOf Val Is String Then
                e.Value = "Yes"
            ElseIf TypeOf Val Is Integer Then
                e.Value = 1
            Else : e.Value = Nothing
            End If
        Case CheckState.Unchecked
            If TypeOf Val Is Boolean Then
                e.Value = False
            ElseIf TypeOf Val Is String Then
                e.Value = "No"
            ElseIf TypeOf Val Is Integer Then
                e.Value = 0
            Else : e.Value = Nothing
            End If
        Case Else
            If TypeOf Val Is Boolean Then
                e.Value = False
            ElseIf TypeOf Val Is String Then
                e.Value = "?"
            ElseIf TypeOf Val Is Integer Then
                e.Value = -1
            Else : e.Value = Nothing
            End If
    End Select
    e.Handled = True
End Sub