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CustomValidator Class

Performs user-defined validation on an input control.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)
public class CustomValidator : BaseValidator
<asp:CustomValidator />

The CustomValidator type exposes the following members.

  NameDescription
Public methodCustomValidatorInitializes a new instance of the CustomValidator class.
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  NameDescription
Public propertyAccessKeyGets or sets the access key that allows you to quickly navigate to the Web server control. (Inherited from WebControl.)
Protected propertyAdapterGets the browser-specific adapter for the control. (Inherited from Control.)
Public propertyAppRelativeTemplateSourceDirectoryGets or sets the application-relative virtual directory of the Page or UserControl object that contains this control. (Inherited from Control.)
Public propertyAssociatedControlIDThis property is not supported. (Inherited from BaseValidator.)
Public propertyAttributesGets the collection of arbitrary attributes (for rendering only) that do not correspond to properties on the control. (Inherited from WebControl.)
Public propertyBackColorGets or sets the background color of the Web server control. (Inherited from WebControl.)
Public propertyBindingContainerInfrastructure. Gets the control that contains this control's data binding. (Inherited from Control.)
Public propertyBorderColorGets or sets the border color of the Web control. (Inherited from WebControl.)
Public propertyBorderStyleGets or sets the border style of the Web server control. (Inherited from WebControl.)
Public propertyBorderWidthGets or sets the border width of the Web server control. (Inherited from WebControl.)
Protected propertyChildControlsCreatedGets a value that indicates whether the server control's child controls have been created. (Inherited from Control.)
Public propertyClientIDGets the control ID for HTML markup that is generated by ASP.NET. (Inherited from Control.)
Public propertyClientIDModeGets or sets the algorithm that is used to generate the value of the ClientID property. (Inherited from Control.)
Protected propertyClientIDSeparatorGets a character value representing the separator character used in the ClientID property. (Inherited from Control.)
Public propertyClientValidationFunctionGets or sets the name of the custom client-side script function used for validation.
Protected propertyContextGets the HttpContext object associated with the server control for the current Web request. (Inherited from Control.)
Public propertyControlsGets a ControlCollection object that represents the child controls for a specified server control in the UI hierarchy. (Inherited from Control.)
Public propertyControlStyleGets the style of the Web server control. This property is used primarily by control developers. (Inherited from WebControl.)
Public propertyControlStyleCreatedGets a value indicating whether a Style object has been created for the ControlStyle property. This property is primarily used by control developers. (Inherited from WebControl.)
Public propertyControlToValidateGets or sets the input control to validate. (Inherited from BaseValidator.)
Public propertyCssClassGets or sets the Cascading Style Sheet (CSS) class rendered by the Web server control on the client. (Inherited from WebControl.)
Public propertyDataItemContainerGets a reference to the naming container if the naming container implements IDataItemContainer. (Inherited from Control.)
Public propertyDataKeysContainerGets a reference to the naming container if the naming container implements IDataKeysControl. (Inherited from Control.)
Protected propertyDesignModeGets a value indicating whether a control is being used on a design surface. (Inherited from Control.)
Public propertyDisplayGets or sets the display behavior of the error message in a validation control. (Inherited from BaseValidator.)
Public propertyEnableClientScriptGets or sets a value indicating whether client-side validation is enabled. (Inherited from BaseValidator.)
Public propertyEnabledGets or sets a value that indicates whether the validation control is enabled. (Inherited from BaseValidator.)
Public propertyEnableThemingGets or sets a value indicating whether themes apply to this control. (Inherited from WebControl.)
Public propertyEnableViewStateGets or sets a value indicating whether the server control persists its view state, and the view state of any child controls it contains, to the requesting client. (Inherited from Control.)
Public propertyErrorMessageGets or sets the text for the error message displayed in a ValidationSummary control when validation fails. (Inherited from BaseValidator.)
Protected propertyEventsGets a list of event handler delegates for the control. This property is read-only. (Inherited from Control.)
Public propertyFontGets the font properties associated with the Web server control. (Inherited from WebControl.)
Public propertyForeColorGets or sets the color of the message displayed when validation fails. (Inherited from BaseValidator.)
Public propertyHasAttributesGets a value indicating whether the control has attributes set. (Inherited from WebControl.)
Protected propertyHasChildViewStateGets a value indicating whether the current server control's child controls have any saved view-state settings. (Inherited from Control.)
Public propertyHeightGets or sets the height of the Web server control. (Inherited from WebControl.)
Public propertyIDGets or sets the programmatic identifier assigned to the server control. (Inherited from Control.)
Protected propertyIdSeparatorInfrastructure. Gets the character used to separate control identifiers. (Inherited from Control.)
Protected propertyIsChildControlStateClearedGets a value indicating whether controls contained within this control have control state. (Inherited from Control.)
Protected propertyIsEnabledGets a value indicating whether the control is enabled. (Inherited from WebControl.)
Protected propertyIsTrackingViewStateGets a value that indicates whether the server control is saving changes to its view state. (Inherited from Control.)
Protected propertyIsUnobtrusiveGets a value that indicates whether the control generates unobtrusive JavaScript. (Inherited from BaseValidator.)
Public propertyIsValidGets or sets a value that indicates whether the associated input control passes validation. (Inherited from BaseValidator.)
Protected propertyIsViewStateEnabledGets a value indicating whether view state is enabled for this control. (Inherited from Control.)
Protected propertyLoadViewStateByIDGets a value indicating whether the control participates in loading its view state by ID instead of index. (Inherited from Control.)
Public propertyNamingContainerGets a reference to the server control's naming container, which creates a unique namespace for differentiating between server controls with the same Control.ID property value. (Inherited from Control.)
Public propertyPageGets a reference to the Page instance that contains the server control. (Inherited from Control.)
Public propertyParentGets a reference to the server control's parent control in the page control hierarchy. (Inherited from Control.)
Protected propertyPropertiesValidGets a value that indicates whether the control specified by the ControlToValidate property is a valid control. (Inherited from BaseValidator.)
Public propertyRenderingCompatibilityGets a value that specifies the ASP.NET version that rendered HTML will be compatible with. (Inherited from Control.)
Protected propertyRenderUplevelGets a value that indicates whether the client's browser supports "uplevel" rendering. (Inherited from BaseValidator.)
Public propertySetFocusOnErrorGets or sets a value that indicates whether focus is set to the control specified by the ControlToValidate property when validation fails. (Inherited from BaseValidator.)
Public propertySiteGets information about the container that hosts the current control when rendered on a design surface. (Inherited from Control.)
Public propertySkinIDGets or sets the skin to apply to the control. (Inherited from WebControl.)
Public propertyStyleGets a collection of text attributes that will be rendered as a style attribute on the outer tag of the Web server control. (Inherited from WebControl.)
Public propertySupportsDisabledAttributeGets a value that indicates whether the control should set the disabled attribute of the rendered HTML element to "disabled" when the control's IsEnabled property is false. (Inherited from Label.)
Public propertyTabIndexGets or sets the tab index of the Web server control. (Inherited from WebControl.)
Protected propertyTagKeyGets the HTML tag that is used to render the Label control. (Inherited from Label.)
Protected propertyTagNameGets the name of the control tag. This property is used primarily by control developers. (Inherited from WebControl.)
Public propertyTemplateControlGets or sets a reference to the template that contains this control. (Inherited from Control.)
Public propertyTemplateSourceDirectoryGets the virtual directory of the Page or UserControl that contains the current server control. (Inherited from Control.)
Public propertyTextGets or sets the text displayed in the validation control when validation fails. (Inherited from BaseValidator.)
Public propertyToolTipGets or sets the text displayed when the mouse pointer hovers over the Web server control. (Inherited from WebControl.)
Public propertyUniqueIDGets the unique, hierarchically qualified identifier for the server control. (Inherited from Control.)
Public propertyValidateEmptyTextGets or sets a Boolean value indicating whether empty text should be validated.
Public propertyValidateRequestModeGets or sets a value that indicates whether the control checks client input from the browser for potentially dangerous values. (Inherited from Control.)
Public propertyValidationGroupGets or sets the name of the validation group to which this validation control belongs. (Inherited from BaseValidator.)
Protected propertyViewStateGets a dictionary of state information that allows you to save and restore the view state of a server control across multiple requests for the same page. (Inherited from Control.)
Protected propertyViewStateIgnoresCaseGets a value that indicates whether the StateBag object is case-insensitive. (Inherited from Control.)
Public propertyViewStateModeGets or sets the view-state mode of this control. (Inherited from Control.)
Public propertyVisibleGets or sets a value that indicates whether a server control is rendered as UI on the page. (Inherited from Control.)
Public propertyWidthGets or sets the width of the Web server control. (Inherited from WebControl.)
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  NameDescription
Protected methodAddAttributesToRenderInfrastructure. Adds the properties of the CustomValidator control to the output stream for rendering on the client. (Overrides BaseValidator.AddAttributesToRender(HtmlTextWriter).)
Protected methodAddedControlCalled after a child control is added to the Controls collection of the Control object. (Inherited from Control.)
Protected methodAddParsedSubObjectNotifies the control that an element was parsed and adds the element to the Label control. (Inherited from Label.)
Public methodApplyStyleCopies any nonblank elements of the specified style to the Web control, overwriting any existing style elements of the control. This method is primarily used by control developers. (Inherited from WebControl.)
Public methodApplyStyleSheetSkinApplies the style properties defined in the page style sheet to the control. (Inherited from Control.)
Protected methodBeginRenderTracingBegins design-time tracing of rendering data. (Inherited from Control.)
Protected methodBuildProfileTreeInfrastructure. Gathers information about the server control and delivers it to the Trace property to be displayed when tracing is enabled for the page. (Inherited from Control.)
Protected methodCheckControlValidationPropertyVerifies whether the specified control is on the page and contains validation properties. (Inherited from BaseValidator.)
Protected methodClearCachedClientIDInfrastructure. Sets the cached ClientID value to null. (Inherited from Control.)
Protected methodClearChildControlStateDeletes the control-state information for the server control's child controls. (Inherited from Control.)
Protected methodClearChildStateDeletes the view-state and control-state information for all the server control's child controls. (Inherited from Control.)
Protected methodClearChildViewStateDeletes the view-state information for all the server control's child controls. (Inherited from Control.)
Protected methodClearEffectiveClientIDModeInfrastructure. Sets the ClientIDMode property of the current control instance and of any child controls to Inherit. (Inherited from Control.)
Protected methodControlPropertiesValidInfrastructure. Checks the properties of the control for valid values. (Overrides BaseValidator.ControlPropertiesValid().)
Public methodCopyBaseAttributesCopies the properties not encapsulated by the Style object from the specified Web server control to the Web server control that this method is called from. This method is used primarily by control developers. (Inherited from WebControl.)
Protected methodCreateChildControlsCalled by the ASP.NET page framework to notify server controls that use composition-based implementation to create any child controls they contain in preparation for posting back or rendering. (Inherited from Control.)
Protected methodCreateControlCollectionCreates a new ControlCollection object to hold the child controls (both literal and server) of the server control. (Inherited from Control.)
Protected methodCreateControlStyleCreates the style object that is used internally by the WebControl class to implement all style related properties. This method is used primarily by control developers. (Inherited from WebControl.)
Public methodDataBind()Binds a data source to the invoked server control and all its child controls. (Inherited from Control.)
Protected methodDataBind(Boolean)Binds a data source to the invoked server control and all its child controls with an option to raise the DataBinding event. (Inherited from Control.)
Protected methodDataBindChildrenBinds a data source to the server control's child controls. (Inherited from Control.)
Protected methodDetermineRenderUplevelDetermines whether the validation control can perform client-side validation. (Inherited from BaseValidator.)
Public methodDisposeEnables a server control to perform final clean up before it is released from memory. (Inherited from Control.)
Protected methodEndRenderTracingEnds design-time tracing of rendering data. (Inherited from Control.)
Protected methodEnsureChildControlsDetermines whether the server control contains child controls. If it does not, it creates child controls. (Inherited from Control.)
Protected methodEnsureIDCreates an identifier for controls that do not have an identifier assigned. (Inherited from Control.)
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodEvaluateIsValidInfrastructure. Overrides the BaseValidator.EvaluateIsValid method. (Overrides BaseValidator.EvaluateIsValid().)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodFindControl(String)Searches the current naming container for a server control with the specified id parameter. (Inherited from Control.)
Protected methodFindControl(String, Int32)Infrastructure. Searches the current naming container for a server control with the specified id and an integer, specified in the pathOffset parameter, which aids in the search. You should not override this version of the FindControl method. (Inherited from Control.)
Public methodFocusSets input focus to a control. (Inherited from Control.)
Protected methodGetControlRenderIDGets the client ID of the specified control. (Inherited from BaseValidator.)
Protected methodGetControlValidationValueGets the value associated with the specified input control. (Inherited from BaseValidator.)
Protected methodGetDesignModeStateInfrastructure. Gets design-time data for a control. (Inherited from Control.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetRouteUrl(Object)Gets the URL that corresponds to a set of route parameters. (Inherited from Control.)
Public methodGetRouteUrl(RouteValueDictionary)Gets the URL that corresponds to a set of route parameters. (Inherited from Control.)
Public methodGetRouteUrl(String, Object)Gets the URL that corresponds to a set of route parameters and a route name. (Inherited from Control.)
Public methodGetRouteUrl(String, RouteValueDictionary)Gets the URL that corresponds to a set of route parameters and a route name. (Inherited from Control.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodGetUniqueIDRelativeToReturns the prefixed portion of the UniqueID property of the specified control. (Inherited from Control.)
Public methodHasControlsDetermines if the server control contains any child controls. (Inherited from Control.)
Protected methodHasEventsReturns a value indicating whether events are registered for the control or any child controls. (Inherited from Control.)
Protected methodIsLiteralContentInfrastructure. Determines if the server control holds only literal content. (Inherited from Control.)
Protected methodLoadControlStateRestores control-state information from a previous page request that was saved by the SaveControlState method. (Inherited from Control.)
Protected methodLoadViewStateLoads the previously saved state for the control. (Inherited from Label.)
Protected methodMapPathSecureRetrieves the physical path that a virtual path, either absolute or relative, maps to. (Inherited from Control.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodMergeStyleCopies any nonblank elements of the specified style to the Web control, but will not overwrite any existing style elements of the control. This method is used primarily by control developers. (Inherited from WebControl.)
Protected methodOnBubbleEventDetermines whether the event for the server control is passed up the page's UI server control hierarchy. (Inherited from Control.)
Protected methodOnDataBindingRaises the DataBinding event. (Inherited from Control.)
Protected methodOnInitInfrastructure. Raises the Init event. (Inherited from BaseValidator.)
Protected methodOnLoadRaises the Load event. (Inherited from Control.)
Protected methodOnPreRenderInfrastructure. Raises the PreRender event. (Inherited from BaseValidator.)
Protected methodOnServerValidateRaises the ServerValidate event for the CustomValidator control.
Protected methodOnUnloadInfrastructure. Raises the Unload event. (Inherited from BaseValidator.)
Protected methodOpenFileGets a Stream used to read a file. (Inherited from Control.)
Protected methodRaiseBubbleEventAssigns any sources of the event and its information to the control's parent. (Inherited from Control.)
Protected methodRegisterValidatorCommonScriptRegisters code on the page for client-side validation. (Inherited from BaseValidator.)
Protected methodRegisterValidatorDeclarationRegisters an ECMAScript array declaration using the array name Page_Validators. (Inherited from BaseValidator.)
Protected methodRemovedControlCalled after a child control is removed from the Controls collection of the Control object. (Inherited from Control.)
Protected methodRenderInfrastructure. Displays the control on the client. (Inherited from BaseValidator.)
Public methodRenderBeginTagRenders the HTML opening tag of the control to the specified writer. This method is used primarily by control developers. (Inherited from WebControl.)
Protected methodRenderChildrenOutputs the content of a server control's children to a provided HtmlTextWriter object, which writes the content to be rendered on the client. (Inherited from Control.)
Protected methodRenderContentsInfrastructure. Renders the contents of the Label into the specified writer. (Inherited from Label.)
Public methodRenderControl(HtmlTextWriter)Outputs server control content to a provided HtmlTextWriter object and stores tracing information about the control if tracing is enabled. (Inherited from Control.)
Protected methodRenderControl(HtmlTextWriter, ControlAdapter)Outputs server control content to a provided HtmlTextWriter object using a provided ControlAdapter object. (Inherited from Control.)
Public methodRenderEndTagRenders the HTML closing tag of the control into the specified writer. This method is used primarily by control developers. (Inherited from WebControl.)
Protected methodResolveAdapterGets the control adapter responsible for rendering the specified control. (Inherited from Control.)
Public methodResolveClientUrlGets a URL that can be used by the browser. (Inherited from Control.)
Public methodResolveUrlConverts a URL into one that is usable on the requesting client. (Inherited from Control.)
Protected methodSaveControlStateSaves any server control state changes that have occurred since the time the page was posted back to the server. (Inherited from Control.)
Protected methodSaveViewStateSaves any state that was modified after the TrackViewState method was invoked. (Inherited from WebControl.)
Protected methodSetDesignModeStateSets design-time data for a control. (Inherited from Control.)
Public methodSetRenderMethodDelegateInfrastructure. Assigns an event handler delegate to render the server control and its content into its parent control. (Inherited from Control.)
Public methodSetTraceData(Object, Object)Sets trace data for design-time tracing of rendering data, using the trace data key and the trace data value. (Inherited from Control.)
Public methodSetTraceData(Object, Object, Object)Sets trace data for design-time tracing of rendering data, using the traced object, the trace data key, and the trace data value. (Inherited from Control.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Protected methodTrackViewStateCauses the control to track changes to its view state so they can be stored in the object's ViewState property. (Inherited from WebControl.)
Public methodValidatePerforms validation on the associated input control and updates the IsValid property. (Inherited from BaseValidator.)
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  NameDescription
Public eventDataBindingOccurs when the server control binds to a data source. (Inherited from Control.)
Public eventDisposedOccurs when a server control is released from memory, which is the last stage of the server control lifecycle when an ASP.NET page is requested. (Inherited from Control.)
Public eventInitOccurs when the server control is initialized, which is the first step in its lifecycle. (Inherited from Control.)
Public eventLoadOccurs when the server control is loaded into the Page object. (Inherited from Control.)
Public eventPreRenderOccurs after the Control object is loaded but prior to rendering. (Inherited from Control.)
Public eventServerValidateOccurs when validation is performed on the server.
Public eventUnloadOccurs when the server control is unloaded from memory. (Inherited from Control.)
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  NameDescription
Public Extension MethodFindDataSourceControlReturns the data source that is associated with the data control for the specified control. (Defined by DynamicDataExtensions.)
Public Extension MethodFindFieldTemplateReturns the field template for the specified column in the specified control's naming container. (Defined by DynamicDataExtensions.)
Public Extension MethodFindMetaTableReturns the metatable object for the containing data control. (Defined by DynamicDataExtensions.)
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  NameDescription
Explicit interface implemetationPrivate methodIAttributeAccessor.GetAttributeInfrastructure. Gets an attribute of the Web control with the specified name. (Inherited from WebControl.)
Explicit interface implemetationPrivate methodIAttributeAccessor.SetAttributeSets an attribute of the Web control to the specified name and value. (Inherited from WebControl.)
Explicit interface implemetationPrivate propertyIControlBuilderAccessor.ControlBuilderFor a description of this member, see IControlBuilderAccessor.ControlBuilder. (Inherited from Control.)
Explicit interface implemetationPrivate methodIControlDesignerAccessor.GetDesignModeStateFor a description of this member, see IControlDesignerAccessor.GetDesignModeState. (Inherited from Control.)
Explicit interface implemetationPrivate methodIControlDesignerAccessor.SetDesignModeStateFor a description of this member, see IControlDesignerAccessor.SetDesignModeState. (Inherited from Control.)
Explicit interface implemetationPrivate methodIControlDesignerAccessor.SetOwnerControlInfrastructure. For a description of this member, see IControlDesignerAccessor.SetOwnerControl. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIControlDesignerAccessor.UserDataFor a description of this member, see IControlDesignerAccessor.UserData. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIDataBindingsAccessor.DataBindingsFor a description of this member, see IDataBindingsAccessor.DataBindings. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIDataBindingsAccessor.HasDataBindingsFor a description of this member, see IDataBindingsAccessor.HasDataBindings. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIExpressionsAccessor.ExpressionsFor a description of this member, see IExpressionsAccessor.Expressions. (Inherited from Control.)
Explicit interface implemetationPrivate propertyIExpressionsAccessor.HasExpressionsFor a description of this member, see IExpressionsAccessor.HasExpressions. (Inherited from Control.)
Explicit interface implemetationPrivate methodIParserAccessor.AddParsedSubObjectFor a description of this member, see IParserAccessor.AddParsedSubObject. (Inherited from Control.)
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Use the CustomValidator control to provide a user-defined validation function for an input control. The CustomValidator control is a separate control from the input control it validates, which allows you to control where the validation message is displayed.

Validation controls always perform validation on the server. They also have complete client-side implementation that allows script-enabled browsers (such as Microsoft Internet Explorer 4.0 and later) to perform validation on the client. Client-side validation enhances the validation process by checking user input before it is sent to the server. This allows errors to be detected on the client before the form is submitted, thus avoiding the round trip of information necessary for server-side validation.

To create a server-side validation function, provide a handler for the ServerValidate event that performs the validation. The string from the input control to validate can be accessed by using the Value property of the ServerValidateEventArgs object passed into the event handler as a parameter. The result of the validation is then stored in the IsValid property of the ServerValidateEventArgs object.

To create a client-side validation function, first add the server-side validation function described earlier. Next, add the client-side validation script function to the ASP.NET (.aspx) page.

If you are using Visual Basic Scripting Edition (VBScript), the function must be in this form:

 Sub ValidationFunctionName(source, arguments)

If you are using JScript, the function must be in this form:

 function ValidationFunctionName(source, arguments)

The source parameter is a reference to the <span> element rendered for the CustomValidator control. This allows you to programmatically control the <span> tag, such as modifying the InnerHtml attribute. The arguments parameter is an object with two properties: Value and IsValid. This parameter allows you to get the value of the control to validate and to indicate whether the value is valid based on your custom validation routine.

Use the ClientValidationFunction property to specify the name of the client-side validation script function associated with the CustomValidator control. Because the script function is executed on the client, the function must be in a language that the target browser supports, such as VBScript or JScript.

NoteNote

When you use the CustomValidator control inside an UpdatePanel control, make sure that the validator control and the control it is associated with are in the same panel. For more information about using the UpdatePanel control for partial-page updates, see Partial-Page Rendering Overview.

Like server-side validation, the string from the input control to validate is accessed by using the Value property of the arguments parameter. Return the result of the validation by setting the IsValid property of the arguments parameter.

Caution noteCaution

When using validator controls, you should always check the results of server-side validation before performing any processing. After a postback but before your event methods are called, the page calls the validator controls and aggregates their results into the Page.IsValid property. (You can also call the validator controls explicitly using the Validate method.) In your own code, you should check that the Page.IsValid property returns true before processing input. Even though script-enabled browsers might prevent a postback from occurring on the client if a validation check has failed, you should always also check Page.IsValid in server code before processing validated data.

Multiple validation controls can be used with an individual input control to validate different criteria. For example, you can apply multiple validation controls on a TextBox control that allows the user to enter the quantity of items to add to a shopping cart. You can use a CustomValidator control to ensure that the value specified is less than the amount in inventory and a RequiredFieldValidator control to ensure that the user enters a value into the TextBox control.

NoteNote

If the input control is empty, no validation functions are called and validation succeeds. Use a RequiredFieldValidator control to require the user to enter data in the input control.

It is possible to use a CustomValidator control without setting the ControlToValidate property. This is commonly done when you are validating multiple input controls or validating input controls that cannot be used with validation controls, such as the CheckBox control. In this case, the Value property of the arguments parameter passed to the event handler for the ServerValidate event and to the client-side validation function always contains an empty string (""). However, these validation functions are still called, where appropriate, to determine validity on both the server and client. To access the value to validate, you must programmatically reference the input control you want to validate and then retrieve the value from the appropriate property. For example, to validate a CheckBox control on the server, do not set the ControlToValidate property of the validation control and use the following code for the handler for the ServerValidate event.

void ServerValidation (object source, ServerValidateEventArgs args)
 {
    args.IsValid = (CheckBox1.Checked == true);
 }

For more information on validation controls, see BaseValidator.

Accessibility

For information about how to configure this control so that it generates markup that conforms to accessibility standards, see Accessibility in Visual Studio and ASP.NET and ASP.NET Controls and Accessibility.

TopicLocation
How to: Validate Against Values in a Database for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Against a Range of Values for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Against a Specific Value for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Against a Data Type for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Specify Layout for In-Place Messages On ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Required Entries for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Display Server Side Custom Validation Messages for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Test Validity Programmatically for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Against Patterns for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Programmatically for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Format Validation Error Messages for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate with a Custom Function for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Disable Validation for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Against Values in a Database for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Against a Range of Values for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Against a Specific Value for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Against a Data Type for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Specify Layout for In-Place Messages On ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Required Entries for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Display Server Side Custom Validation Messages for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Test Validity Programmatically for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Against Patterns for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate Programmatically for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Format Validation Error Messages for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Validate with a Custom Function for ASP.NET Server ControlsBuilding ASP .NET Web Applications
How to: Disable Validation for ASP.NET Server ControlsBuilding ASP .NET Web Applications
Walkthrough: Validating User Input in a Web Forms PageBuilding ASP .NET Web Applications in Visual Studio

The following code example demonstrates how to create a server-side CustomValidator control.

Security noteSecurity Note

This example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview.


<%@ Page Language="C#" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>CustomValidator ServerValidate Example</title>
<script runat="server">

      void ValidateBtn_OnClick(object sender, EventArgs e) 
      { 

         // Display whether the page passed validation.
         if (Page.IsValid) 
         {

            Message.Text = "Page is valid.";

         }

         else 
         {

            Message.Text = "Page is not valid!";

         }

      }

      void ServerValidation(object source, ServerValidateEventArgs args)
      {

         try 
         {

            // Test whether the value entered into the text box is even.
            int i = int.Parse(args.Value);
            args.IsValid = ((i%2) == 0);

         }

         catch(Exception ex)
         {

            args.IsValid = false;

         }

      }

   </script>    

</head>
<body>

   <form id="form1" runat="server">

      <h3>CustomValidator ServerValidate Example</h3>

      <asp:Label id="Message"  
           Text="Enter an even number:" 
           Font-Names="Verdana" 
           Font-Size="10pt" 
           runat="server"
           AssociatedControlID="Text1"/>

      <br />

      <asp:TextBox id="Text1" 
           runat="server" />

      &nbsp;&nbsp;

      <asp:CustomValidator id="CustomValidator1"
           ControlToValidate="Text1"
           Display="Static"
           ErrorMessage="Not an even number!"
           ForeColor="green"
           Font-Names="verdana" 
           Font-Size="10pt"
           OnServerValidate="ServerValidation"
           runat="server"/>

      <br />

      <asp:Button id="Button1"
           Text="Validate" 
           OnClick="ValidateBtn_OnClick" 
           runat="server"/>

   </form>

</body>
</html>

The following code example demonstrates how to create a client-side CustomValidator control.

<%@ Page Language="C#" AutoEventWireup="True" %>

<html>
<head>

   <script runat="server">

      void ValidateBtn_OnClick(object sender, EventArgs e) 
      { 
         // Display whether the page passed validation.
         if (Page.IsValid) 
         {
            Message.Text = "Page is valid.";
         }

         else 
         {
            Message.Text = "Page is not valid!";
         }
      }

      void ServerValidation(object source, ServerValidateEventArgs args)
      {
         try 
         {
            // Test whether the value entered into the text box is even.
            int i = int.Parse(args.Value);
            args.IsValid = ((i%2) == 0);
         }

         catch(Exception ex)
         {
            args.IsValid = false;
         }
      }

   </script>    

</head>
<body>

   <form id="Form1" runat="server">

      <h3>CustomValidator ServerValidate Example</h3>

      <asp:Label id="Message"  
           Text="Enter an even number:" 
           Font-Name="Verdana" 
           Font-Size="10pt" 
           runat="server"/>

      <p>

      <asp:TextBox id="Text1" 
           runat="server" />

      &nbsp;&nbsp;

      <asp:CustomValidator id="CustomValidator1"
           ControlToValidate="Text1"
           ClientValidationFunction="ClientValidate"
           OnServerValidate="ServerValidation"
           Display="Static"
           ErrorMessage="Not an even number!"
           ForeColor="green"
           Font-Name="verdana" 
           Font-Size="10pt"
           runat="server"/>

      <p>

      <asp:Button id="Button1"
           Text="Validate" 
           OnClick="ValidateBtn_OnClick" 
           runat="server"/>

   </form>
</body>
</html>

<script language="javascript"> 
   function ClientValidate(source, arguments)
   {
        if (arguments.Value % 2 == 0 ){
            arguments.IsValid = true;
        } else {
            arguments.IsValid = false;
        }
   }
</script>

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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