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Attribute.GetCustomAttribute Method (MemberInfo, Type)

Retrieves a custom attribute applied to a member of a type. Parameters specify the member, and the type of the custom attribute to search for.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

public static Attribute GetCustomAttribute(
	MemberInfo element,
	Type attributeType
)

Parameters

element
Type: System.Reflection.MemberInfo

An object derived from the MemberInfo class that describes a constructor, event, field, method, or property member of a class.

attributeType
Type: System.Type

The type, or a base type, of the custom attribute to search for.

Return Value

Type: System.Attribute
A reference to the single custom attribute of type attributeType that is applied to element, or null if there is no such attribute.

ExceptionCondition
ArgumentNullException

element or attributeType is null.

ArgumentException

attributeType is not derived from Attribute.

NotSupportedException

element is not a constructor, method, property, event, type, or field.

AmbiguousMatchException

More than one of the requested attributes was found.

TypeLoadException

A custom attribute type cannot be loaded.

A match is determined in the same way described in the Return Value section of Type.IsAssignableFrom.

NoteNote

Starting with the .NET Framework version 2.0, this method returns security attributes on types, methods, and constructors if the attributes are stored in the new metadata format. Assemblies compiled with version 2.0 or later use the new format. Dynamic assemblies and assemblies compiled with earlier versions of the .NET Framework use the old XML format. See Emitting Declarative Security Attributes.

The following code example illustrates the use of the GetCustomAttribute method taking a MemberInfo as a parameter.

using System;
using System.Reflection;

namespace IsDef4CS 
{
    public class TestClass 
    {
        // Assign the Obsolete attribute to a method.
        [Obsolete("This method is obsolete. Use Method2 instead.")]
        public void Method1()
        {}
        public void Method2()
        {}
    }

    public class DemoClass 
    {
        static void Main(string[] args) 
        {
            // Get the class type to access its metadata.
            Type clsType = typeof(TestClass);
            // Get the MethodInfo object for Method1.
            MethodInfo mInfo = clsType.GetMethod("Method1");
            // See if the Obsolete attribute is defined for this method. 
            bool isDef = Attribute.IsDefined(mInfo, typeof(ObsoleteAttribute));
            // Display the result.
            Console.WriteLine("The Obsolete Attribute {0} defined for {1} of class {2}.",
                isDef ? "is" : "is not", mInfo.Name, clsType.Name);
            // If it's defined, display the attribute's message. 
            if (isDef) 
            {
                ObsoleteAttribute obsAttr = 
                                 (ObsoleteAttribute)Attribute.GetCustomAttribute( 
                                                    mInfo, typeof(ObsoleteAttribute));
                if (obsAttr != null)
                    Console.WriteLine("The message is: \"{0}\".",
                        obsAttr.Message);
                else
                    Console.WriteLine("The message could not be retrieved.");
            }
        }
    }
}

/*
 * Output:
 * The Obsolete Attribute is defined for Method1 of class TestClass.
 * The message is: "This method is obsolete. Use Method2 instead.".
 */

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

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.

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