How to: Validate Data via DXValidationProvider Component

• Oct 25, 2019
• 3 minutes to read

This example demonstrates how to validate data via the DXValidationProvider component. In this example, validation rules (built-in and custom) are created in code, and associated with editors using the DXValidationProvider.SetValidationRule method.

The CustomValidationRule class represents a custom validation rule that checks whether the editor’s value begins with “Dr.”, “Mr.”, “Mrs.”, “Miss” or “Ms.”.

C#

using DevExpress.XtraEditors.DXErrorProvider;

// Validate editors manually (when the OK button is clicked)
dxValidationProvider1.ValidationMode = ValidationMode.Manual;

// ...
ConditionValidationRule containsValidationRule = new ConditionValidationRule();
containsValidationRule.ConditionOperator = ConditionOperator.Contains;
containsValidationRule.Value1 = '@';
containsValidationRule.ErrorText = "Please enter a valid email";
containsValidationRule.ErrorType = ErrorType.Warning;

CompareAgainstControlValidationRule compValidationRule = 
    new CompareAgainstControlValidationRule();
compValidationRule.Control = notEmptyTextEdit;
compValidationRule.CompareControlOperator = CompareControlOperator.Equals;
compValidationRule.ErrorText = "Please enter a value that equals to the first editor's value";
compValidationRule.CaseSensitive = true;

CustomValidationRule customValidationRule = new CustomValidationRule();
customValidationRule.ErrorText = "Please enter a valid person name";
customValidationRule.ErrorType = ErrorType.Warning;

dxValidationProvider1.SetValidationRule(containsTextEdit, containsValidationRule);
dxValidationProvider1.SetValidationRule(compareTextEdit, compValidationRule);
dxValidationProvider1.SetValidationRule(customTextEdit, customValidationRule);


private void buttonOk_Click(object sender, EventArgs e) {
    dxValidationProvider1.Validate();
}

// Represents a custom validation rule.
public class CustomValidationRule : ValidationRule {
    public override bool Validate(Control control, object value) {
        string str = (string)value;
        string[] values = new string[] { "Dr.", "Mr.", "Mrs.", "Miss", "Ms." };
        bool res = false;
        foreach(string val in values) {
            if(ValidationHelper.Validate(str, ConditionOperator.BeginsWith, 
                val, null, null, false)) {
                string name = str.Substring(val.Length);
                if(name.Trim().Length > 0) res = true;
            }
        }
        return res;
    }
}

VB.NET

Imports DevExpress.XtraEditors.DXErrorProvider

' Validate editors manually (when the OK button is clicked)
dxValidationProvider1.ValidationMode = ValidationMode.Manual
' ...
Dim containsValidationRule As New ConditionValidationRule()
containsValidationRule.ConditionOperator = ConditionOperator.Contains
containsValidationRule.Value1 = "@"
containsValidationRule.ErrorText = "Please enter a valid email"
containsValidationRule.ErrorType = ErrorType.Warning

Dim compValidationRule As New CompareAgainstControlValidationRule()
compValidationRule.Control = notEmptyTextEdit
compValidationRule.CompareControlOperator = CompareControlOperator.Equals
compValidationRule.ErrorText = "Please enter a value that equals to the first editor's value"
compValidationRule.CaseSensitive = True

Dim customValidationRule As New CustomValidationRule()
customValidationRule.ErrorText = "Please enter a valid person name"
customValidationRule.ErrorType = ErrorType.Warning

dxValidationProvider1.SetValidationRule(containsTextEdit, containsValidationRule)
dxValidationProvider1.SetValidationRule(compareTextEdit, compValidationRule)
dxValidationProvider1.SetValidationRule(customTextEdit, customValidationRule)

Private Sub ButtonOK_Click(sender As Object, e As EventArgs) Handles ButtonOK.Click
    dxValidationProvider1.Validate()
End Sub


' Represents a custom validation rule.
Public Class CustomValidationRule
   Inherits ValidationRule

   Public Overrides Function Validate(control As Control, value As Object) As Boolean
      Dim str As String = CStr(value)
      Dim values() As String = {"Dr.", "Mr.", "Mrs.", "Miss", "Ms."}
      Dim res As Boolean = False
      Dim val As String
      For Each val In  values
         If ValidationHelper.Validate(str, ConditionOperator.BeginsWith, _ 
             val, Nothing, Nothing, False) Then
            Dim name As String = str.Substring(val.Length)
            If name.Trim().Length > 0 Then
               res = True
            End If
         End If
      Next val
      Return res
   End Function
End Class