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.
Assembly: mscorlib (in mscorlib.dll)
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.AttributeA reference to the single custom attribute of type attributeType that is applied to element, or null if there is no such attribute.
| Exception | Condition |
|---|---|
| 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.
Note |
|---|
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 [Obsolete("This method is obsolete.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.". */
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
