VerificationAttribute Class
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VerificationAttribute Class

 

Defines the metadata attribute of a Web content accessibility rule. This class cannot be inherited.

Namespace:   System.Web.UI
Assembly:  System.Web (in System.Web.dll)

System.Object
  System.Attribute
    System.Web.UI.VerificationAttribute

[AttributeUsageAttribute(AttributeTargets.Class | AttributeTargets.Property, 
	AllowMultiple = true)]
public sealed class VerificationAttribute : Attribute

NameDescription
System_CAPS_pubmethodVerificationAttribute(String, String, VerificationReportLevel, Int32, String)

Initializes a new instance of the VerificationAttribute class with accessibility guideline, checkpoint, reporting level, checkpoint priority, and error message.

System_CAPS_pubmethodVerificationAttribute(String, String, VerificationReportLevel, Int32, String, VerificationRule, String)

Initializes a new instance of the VerificationAttribute class with accessibility guideline, checkpoint, reporting level, checkpoint priority, error message, VerificationRule.value, and related conditional property.

System_CAPS_pubmethodVerificationAttribute(String, String, VerificationReportLevel, Int32, String, VerificationRule, String, VerificationConditionalOperator, String, String)

Initializes a new instance of the VerificationAttribute class with accessibility guideline, checkpoint, reporting level, checkpoint priority, error message, VerificationRule.value, related conditional property, a related conditional property value, and a reference guideline URL.

NameDescription
System_CAPS_pubpropertyCheckpoint

Gets the accessibility checkpoint reference in the specified Guideline property.

System_CAPS_pubpropertyConditionalProperty

Gets the left side of a conditional expression used as part of the verification accessibility checkpoint.

System_CAPS_pubpropertyConditionalValue

Gets the right side of a conditional expression used as part of the verification accessibility checkpoint.

System_CAPS_pubpropertyGuideline

Gets the guideline that used for accessibility checking.

System_CAPS_pubpropertyGuidelineUrl

Gets the URL the can be used to get more information on the accessibility guidelines given in the Guideline property.

System_CAPS_pubpropertyMessage

Gets a message string when the accessibility checkpoint verification rule is true.

System_CAPS_pubpropertyPriority

Gets the priority of the accessibility checkpoint.

System_CAPS_pubpropertyTypeId

When implemented in a derived class, gets a unique identifier for this Attribute.(Inherited from Attribute.)

System_CAPS_pubpropertyVerificationConditionalOperator

Gets a VerificationConditionalOperator enumeration value indication how the accessibility checkpoint is verified.

System_CAPS_pubpropertyVerificationReportLevel

Gets a VerificationReportLevel enumeration value indicating how the accessibility checkpoint is used.

System_CAPS_pubpropertyVerificationRule

Gets a VerificationRule enumeration value indicating how the accessibility checkpoint is used.

NameDescription
System_CAPS_pubmethodEquals(Object)

This API supports the product infrastructure and is not intended to be used directly from your code. Returns a value that indicates whether this instance is equal to a specified object.(Inherited from Attribute.)

System_CAPS_pubmethodGetHashCode()

Returns the hash code for this instance.(Inherited from Attribute.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodIsDefaultAttribute()

When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.(Inherited from Attribute.)

System_CAPS_pubmethodMatch(Object)

When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.(Inherited from Attribute.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can be used to get the type information for an interface.(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.GetTypeInfoCount(UInt32)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).(Inherited from Attribute.)

System_CAPS_pubinterfaceSystem_CAPS_privmethod_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.(Inherited from Attribute.)

An instance of the VerificationAttribute class defines a Web content accessibility rule that can be verified. For more information on Web Content Accessibility Guidelines, see the World Wide Web Consortium (W3C) Web site.

The minimal amount of information required to define an instance of a VerificationAttribute includes:

  • A guideline that the verification rule represents. The value specified in the constructor sets the Guideline property.

  • A checkpoint of the guideline. The value specified in the constructor sets the Checkpoint property.

  • A checkpoint priority. The value specified in the constructor sets the Priority property.

  • A VerificationReportLevel enumeration value that represents the reporting level that should be rule belongs to. The value specified in the constructor sets the VerificationReportLevel property.

  • A message that is reported when the verification rule is true. The value specified in the constructor sets the Message property.

Optional properties of the verification rule that can be specified when creating an instance:

  • A VerificationRule enumeration value that represents how the verification rule should be interpreted. The value specified in the constructor sets the VerificationRule property.

  • A VerificationConditionalOperator enumeration value that represents the operator in the conditional expression used to test the verification rule. The value specified in the constructor sets the VerificationConditionalOperator property.

  • An accessibility reference guideline URL. The value specified in the constructor sets the GuidelineUrl property.

  • A conditional value representing the right side of a conditional expression. The value specified in the constructor sets the ConditionalValue property.

  • A conditional property representing the left side of a conditional expression. The value specified in the constructor sets the ConditionalProperty property.

The VerificationAttribute metadata can be defined class, property, and indexer declarations.

For more information about using attributes, see Extending Metadata Using Attributes.

The following code example demonstrates using the VerificationAttribute class. In the verification metadata definition, the guidelines used are "WCAG," the Web Content Accessibility Guideline, and "ADA," Americans with Disabilities Act Guidelines. For more information, see the World Wide Web Consortium (W3C) Web site.

The checkpoints used are "1.1" and "1194.22(a)" for WCAG and ADA, respectively, checkpoints for ensuring that a text equivalent exists for non-text elements. The VerificationAttribute is applied to the ImageText property that represents the text equivalent of another property called ImageProperty. If the ImageText property is not set, the accessibility verification will return the message "The image is missing a text equivalent."

[Verification("ADA", "1194.22(a)", 
	VerificationReportLevel.Error, 1,
	"The image is missing a text equivalent.", 
	VerificationRule.NotEmptyString, "ImageUrl"),
Verification("WCAG", "1.1", 
	VerificationReportLevel.Error, 1, 
	"The image is missing an text equivalent.", 
	VerificationRule.NotEmptyString, "ImageUrl")]
public virtual String ImageText
{
	get
	{
		object obj = ViewState["ImageText"];
		return ((obj == null) ? String.Empty : (string)obj);
	}
	set
	{
		ViewState["ImageText"] = value;
	}
}
public virtual String ImageUrl
{
	get 
	{
		object obj = ViewState["ImageUrl"];
		return ((obj == null) ? String.Empty : (string)obj);
	}
	set 
	{ 
		ViewState["ImageUrl"] = value;
	}
}

.NET Framework
Available since 2.0

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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