GridView Column validation, display error message don't loose focus

Question

I need to validate a gridView column such as the sum of all elements in the column are <=100;

If the user enters a value and the sum exceeds the limit i want to display a custom error message.

I've tried using this event on the column's repositoryedit:

 void pinEditRepositoryItem_Validating(object sender, System.ComponentModel.CancelEventArgs e)
    {
        e.Cancel = true;
        gridview1.SetColumnError(m_imixGridView.Columns["MyColumn"], "ColumnSum must be <= 100", DevExpress.XtraEditors.DXErrorProvider.ErrorType.Critical);
    }

However, when setting

              e.Cancel = true;

I get the default message "Invalid Value".

If i use

       gridview1.SetColumnError(m_imixGridView.Columns["MyColumn"], "ColumnSum must be <= 100", DevExpress.XtraEditors.DXErrorProvider.ErrorType.Critical);

only, the error message is correct but if i click outside the focus is lost.

I've seen that there are multiple methods for validating rows but didn't find a solution that will suit best in this case.

Is it possible to disable 'unfocus' on a cell if the validation fails?

Thanks a lot!

Solution

Source

I am afraid it is difficult to determine the cause of the issue based on the provided information. Generally, the ValidatingEditor event fires when an active editor is closed, and its value is changed. The ValidateRow event fires when a current row loses focus, and some of its values has been changed.

I suggest you to go through following links:
Validating Rows
Validating Editors
BaseView.ValidatingEditor Event

Check this example:

using DevExpress.XtraGrid.Views.Grid;
using DevExpress.XtraEditors.Controls;

private void gridView1_ValidatingEditor(object sender, BaseContainerValidateEditorEventArgs e) {
    GridView view = sender as GridView;
    if(view.FocusedColumn.FieldName == "Discount") {
        //Get the currently edited value 
        double discount = Convert.ToDouble(e.Value);
        //Specify validation criteria 
        if(discount < 0) {
            e.Valid = false;
            e.ErrorText = "Enter a positive value";
        }
        if(discount > 0.2) {
            e.Valid = false;
            e.ErrorText = "Reduce the amount (20% is maximum)";
        }
    }
}

private void gridView1_InvalidValueException(object sender, InvalidValueExceptionEventArgs e) {
    //Do not perform any default action 
    e.ExceptionMode = DevExpress.XtraEditors.Controls.ExceptionMode.NoAction;
    //Show the message with the error text specified 
    MessageBox.Show(e.ErrorText);
}

Editor validation takes place when attempting to save the edit value (using the PostEditor method) or when closing the active editor. First, the automatic validation is performed. The editor determines whether it can accept the entered value. After the automatic validation has been performed, the ValidatingEditor event is raised. Handle this event to implement custom constraints on cell values.

If your condition fails then set the e.Valid = false; and the e.ErrorText = "ColumnSum must be <= 100"; and also handle the InvalidValueException event of gridview.