ParameterInfo.GetCustomAttributes Method

Definition

Gets the custom attributes applied to this parameter.

Overloads

GetCustomAttributes(Type, Boolean)

Gets the custom attributes of the specified type or its derived types that are applied to this parameter.

GetCustomAttributes(Boolean)

Gets all the custom attributes defined on this parameter.

GetCustomAttributes(Type, Boolean)

Gets the custom attributes of the specified type or its derived types that are applied to this parameter.

public:
 virtual cli::array <System::Object ^> ^ GetCustomAttributes(Type ^ attributeType, bool inherit);
public virtual object[] GetCustomAttributes (Type attributeType, bool inherit);
abstract member GetCustomAttributes : Type * bool -> obj[]
override this.GetCustomAttributes : Type * bool -> obj[]
Public Overridable Function GetCustomAttributes (attributeType As Type, inherit As Boolean) As Object()

Parameters

attributeType
Type

The custom attributes identified by type.

inherit
Boolean

This argument is ignored for objects of this type.

Returns

Object[]

An array that contains the custom attributes of the specified type or its derived types.

Implements

Exceptions

The type must be a type provided by the underlying runtime system.

attributeType is null.

A custom attribute type could not be loaded.

Remarks

This method ignores the inherit parameter. To search the inheritance chain for attributes on parameters, use the appropriate overloads of the Attribute.GetCustomAttributes method.

GetCustomAttributes(Boolean)

Gets all the custom attributes defined on this parameter.

public:
 virtual cli::array <System::Object ^> ^ GetCustomAttributes(bool inherit);
public virtual object[] GetCustomAttributes (bool inherit);
abstract member GetCustomAttributes : bool -> obj[]
override this.GetCustomAttributes : bool -> obj[]
Public Overridable Function GetCustomAttributes (inherit As Boolean) As Object()

Parameters

inherit
Boolean

This argument is ignored for objects of this type.

Returns

Object[]

An array that contains all the custom attributes applied to this parameter.

Implements

Exceptions

A custom attribute type could not be loaded.

Examples

The following example shows how custom attributes that have been applied to the parameters of methods can be retrieved at run time. The example defines a custom attribute named MyAttribute that can be applied to parameters. The example then defines a class named MyClass with a method named MyMethod, and applies MyAttribute to a parameter of the method.

When the example is run, it uses the GetCustomAttributes(Boolean) method to retrieve the custom attributes that have been applied to all parameters of all methods in MyClass, and displays them at the console.

using namespace System;
using namespace System::Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets::Parameter)]
public ref class MyAttribute: public Attribute
{
private:
   String^ myName;

public:
   MyAttribute( String^ name )
   {
      myName = name;
   }

   property String^ Name 
   {
      String^ get()
      {
         return myName;
      }
   }
};

// Define a class which has a custom attribute associated with one of the 
// parameters of a method. 
public ref class MyClass1
{
public:
   void MyMethod( 
      [MyAttribute("This is an example parameter attribute")]
      int i ) {}
};

void main()
{
   // Get the type of the class 'MyClass1'.
   Type^ myType = MyClass1::typeid;

   // Get the members associated with the class 'MyClass1'.
   array<MethodInfo^>^myMethods = myType->GetMethods();

   // Display the attributes for each of the parameters of each method of the class 'MyClass1'.
   for ( int i = 0; i < myMethods->Length; i++ )
   {
      // Get the parameters for the method.
      array<ParameterInfo^>^myParameters = myMethods[ i ]->GetParameters();

      if ( myParameters->Length > 0 )
      {
         Console::WriteLine( "\nThe parameters for the method \"{0}\" that have custom attributes are:", myMethods[ i ] );
         for ( int j = 0; j < myParameters->Length; j++ )
         {
            // Get the attributes of type 'MyAttribute' for each parameter.
            array<Object^>^myAttributes = myParameters[ j ]->GetCustomAttributes( MyAttribute::typeid, false );

            if ( myAttributes->Length > 0 )
            {
               Console::WriteLine( "Parameter {0}, name = {1}, type = {2} has attributes:",
                  myParameters[ j ]->Position, 
                  myParameters[ j ]->Name, 
                  myParameters[ j ]->ParameterType );
               for ( int k = 0; k < myAttributes->Length; k++ )
               {
                  Console::WriteLine( "\t{0}", myAttributes[ k ] );
               }
            }
         }
      }
   }
}
/* This code example produces the following output:

The parameters for the method Void MyMethod(Int32) that have custom attributes are :
Parameter 0, name = i, type = System.Int32 has attributes:
        MyAttribute

The parameters for the method Boolean Equals(System.Object) that have custom attributes are :
 */
using System;
using System.Reflection;

// Define a custom attribute with one named parameter.
[AttributeUsage(AttributeTargets.Parameter)]
public class MyAttribute : Attribute
{
    private string myName;
    public MyAttribute(string name)
    {
        myName = name;
    }
    public string Name 
    {
        get 
        {
            return myName;
        }
    }
}

// Define a class which has a custom attribute associated with one of the 
// parameters of a method. 
public class MyClass1
{
    public void MyMethod(
        [MyAttribute("This is an example parameter attribute")]
        int i)
    {
        return;
    }
}

public class MemberInfo_GetCustomAttributes 
{
    public static void Main()
    {
        // Get the type of the class 'MyClass1'.
        Type myType = typeof(MyClass1);
        // Get the members associated with the class 'MyClass1'.
        MethodInfo[] myMethods = myType.GetMethods();

        // Display the attributes for each of the parameters of each method of the class 'MyClass1'.
        for(int i = 0; i < myMethods.Length; i++)
        {
            // Get the parameters for the method.
            ParameterInfo[] myParameters = myMethods[i].GetParameters();

            if (myParameters.Length > 0)
            {
                Console.WriteLine("\nThe parameters for the method {0} that have custom attributes are :", myMethods[i]);
                for(int j = 0; j < myParameters.Length; j++)
                {
                    // Get the attributes of type 'MyAttribute' for each parameter.
                    Object[] myAttributes = myParameters[j].GetCustomAttributes(typeof(MyAttribute), false);
 
                    if (myAttributes.Length > 0)
                    {
                        Console.WriteLine("Parameter {0}, name = {1}, type = {2} has attributes: ", 
                            myParameters[j].Position, myParameters[j].Name, myParameters[j].ParameterType);
                        for(int k = 0; k < myAttributes.Length; k++)
                        {
                            Console.WriteLine("\t{0}", myAttributes[k]);
                        }
                    }
                }
            }
        }  
    }
}
/* This code example produces the following output:

The parameters for the method Void MyMethod(Int32) that have custom attributes are :
Parameter 0, name = i, type = System.Int32 has attributes:
        MyAttribute

The parameters for the method Boolean Equals(System.Object) that have custom attributes are :
 */
Imports System.Reflection

' Define a custom attribute with one named parameter.
<AttributeUsage(AttributeTargets.Parameter)> Public Class MyAttribute
    Inherits Attribute
    Private myName As String

    Public Sub New(ByVal name As String)
        myName = name
    End Sub 

    Public ReadOnly Property Name() As String
        Get
            Return myName
        End Get
    End Property
End Class 

' Define a class which has a custom attribute associated with one of 
' the parameters of a method. 
Public Class MyClass1

    Public Sub MyMethod( _
            <MyAttribute("This is an example parameter attribute")> _
            ByVal i As Integer _
        )
        Return
    End Sub 
End Class 


Public Class MemberInfo_GetCustomAttributes

    Public Shared Sub Main()
        ' Get the type of the class 'MyClass1'.
        Dim myType As Type = GetType(MyClass1)
        ' Get the members associated with the class 'MyClass1'.
        Dim myMethods As MethodInfo() = myType.GetMethods()

        ' Display the attributes for each of the parameters of each method of the class 'MyClass1'.
        For i As Integer = 0 To myMethods.Length - 1
            ' Get the parameters for the method.
            Dim myParameters As ParameterInfo() = myMethods(i).GetParameters()

            If myParameters.Length > 0 Then
                Console.WriteLine(vbCrLf & "The parameters for the method {0} that have custom attributes are : ", myMethods(i))
                For j As Integer = 0 To myParameters.Length - 1
                    ' Get the attributes of type 'MyAttribute' for each parameter.
                    Dim myAttributes As Object() = myParameters(j).GetCustomAttributes(GetType(MyAttribute), False)

                    If myAttributes.Length > 0 Then
                        Console.WriteLine("Parameter {0}, name = {1}, type = {2} has attributes: ", _
                            myParameters(j).Position, myParameters(j).Name, myParameters(j).ParameterType)
                        For k As Integer = 0 To myAttributes.Length - 1
                            Console.WriteLine(vbTab & "{0}", myAttributes(k))
                        Next k
                    End If
                Next j
            End If
        Next i
    End Sub 
End Class 

' This code example produces the following output:
'
'The parameters for the method Void MyMethod(Int32) that have custom attributes are :
'Parameter 0, name = i, type = System.Int32 has attributes:
'        MyAttribute
'
'The parameters for the method Boolean Equals(System.Object) that have custom attributes are :

Remarks

This method ignores the inherit parameter. To search the inheritance chain for attributes on parameters, use the appropriate overloads of the Attribute.GetCustomAttributes method.

Applies to