ASPxEdit.Validation Event
Allows you to specify whether the value entered into the editor is valid, and whether the editor is allowed to lose focus.
Namespace: DevExpress.Web
Assembly: DevExpress.Web.v24.1.dll
NuGet Package: DevExpress.Web
Declaration
Event Data
The Validation event's data class is ValidationEventArgs. The following properties provide information specific to this event:
| Property | Description |
|---|---|
| ErrorText | Gets or sets the error description. |
| IsValid | Gets or sets a value specifying whether the validated value is valid. |
| Value | Gets or sets the currently validated value. |
Remarks
The Validation event is raised when it is required to validate the editor’s value (for instance, when a value is selected within an editor’s dropdown window or an editor is about to lose focus).
Handle the Validation event to test the editor’s edit value against custom validation criteria. If the entered value obtained via the ValidationEventArgs.Value property doesn’t meet your restrictions, you can prevent the editor from accepting this value (and losing focus) by setting the event parameter’s ValidationEventArgs.IsValid property to false. Then, end users will be forced to correct the edited value. For example, you can check whether the entered text contains only appropriate characters or a numeric value falls into a predefined range, etc.
Additionally, you can provide a text explaining why the validation has failed by assigning a descriptive text to the ValidationEventArgs.ErrorText property. When the ValidationEventArgs.IsValid property is false, the specified text will be displayed within a specific message box.
Example
This example demonstrates how to validate editors in a container on the server side. The ASPxEdit.ValidateEditorsInContainer method is used to determine the validity of editors within a callback panel.
<title>How to validate editors in container </title>
<script type="text/javascript" language="javascript">
function Validate(s, e) {
if (ASPxClientEdit.ValidateGroup('testGroup'))
ClientCallbackPanelDemo.PerformCallback('');
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<dx:ASPxButton ID="ASPxButtonSave" runat="server" Text="Validate" AutoPostBack="False">
<ClientSideEvents Click="Validate" />
</dx:ASPxButton>
<br />
<dx:ASPxCallbackPanel ID="ASPxCallbackPanelDemo" runat="server" HideContentOnCallback="False"
ClientInstanceName="ClientCallbackPanelDemo" OnCallback="ASPxCallbackPanelDemo_Callback">
<PanelCollection>
<dx:PanelContent ID="PanelContent1" runat="server">
<table cellspacing="0" cellpadding="4" runat="server" id="serverContainer">
<tr>
<td style="width: 60px;">
<dx:ASPxLabel runat="server" ID="NameLabel" AssociatedControlID="txtNum1" Text="Number 1:" />
</td>
<td>
<dx:ASPxTextBox ID="txtNum1" runat="server" Width="170px" OnValidation="ASPxTextBoxTest_Validation">
<ValidationSettings ValidationGroup="testGroup">
<RequiredField IsRequired="True" ErrorText="Number 1 is required" />
</ValidationSettings>
</dx:ASPxTextBox>
</td>
</tr>
<tr>
<td style="width: 60px;">
<dx:ASPxLabel runat="server" ID="ASPxLabel1" AssociatedControlID="txtNum2" Text="Number 2:" />
</td>
<td>
<dx:ASPxTextBox ID="txtNum2" runat="server" Width="170px" OnValidation="ASPxTextBoxTest_Validation">
<ValidationSettings ValidationGroup="testGroup">
<RequiredField IsRequired="True" ErrorText="Number 2 is required"/>
</ValidationSettings>
</dx:ASPxTextBox>
</td>
</tr>
</table>
</dx:PanelContent>
</PanelCollection>
</dx:ASPxCallbackPanel>
</div>
</form>
</body>
</html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using DevExpress.Web.ASPxEditors;
using DevExpress.Web.ASPxCallbackPanel;
public partial class _Default : System.Web.UI.Page {
protected void Page_Init (object sender, EventArgs e) {
}
protected void ASPxCallbackPanelDemo_Callback (object sender, DevExpress.Web.CallbackEventArgsBase e) {
ASPxCallbackPanel callbackPanel = (ASPxCallbackPanel)sender;
bool isValid = ASPxEdit.ValidateEditorsInContainer(callbackPanel);
}
protected void ASPxTextBoxTest_Validation (object sender, ValidationEventArgs e) {
ASPxTextBox txt = sender as ASPxTextBox;
int val;
bool result = Int32.TryParse(txt.Text, out val);
e.IsValid = result;
e.ErrorText = "An input value should be a number";
}
}