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Type.GetField Method (String, BindingFlags)

.NET Framework 1.1

Searches for the specified field, using the specified binding constraints.

[Visual Basic]
Overloads Public MustOverride Function GetField( _
   ByVal name As String, _
   ByVal bindingAttr As BindingFlags _
) As FieldInfo Implements IReflect.GetField
[C#]
public abstract FieldInfo GetField(
 string name,
 BindingFlags bindingAttr
);
[C++]
public: virtual FieldInfo* GetField(
 String* name,
 BindingFlags bindingAttr
) = 0;
[JScript]
public abstract function GetField(
   name : String,
 bindingAttr : BindingFlags
) : FieldInfo;

Parameters

name
The String containing the name of the data field to get.
bindingAttr
A bitmask comprised of one or more BindingFlags that specify how the search is conducted.

-or-

Zero, to return a null reference (Nothing in Visual Basic).

Return Value

A FieldInfo object representing the field that matches the specified requirements, if found; otherwise, a null reference (Nothing in Visual Basic).

Implements

IReflect.GetField

Exceptions

Exception Type Condition
ArgumentNullException name is a null reference (Nothing in Visual Basic).

Remarks

The following table shows what members of a base class are returned by the Get methods when reflecting on a type.

Member Type Static Non-Static
Constructor No No
Field No Yes. A field is always hide-by-name-and-signature.
Event Not applicable The common type system rule is that the inheritance is the same as that of the methods that implement the property. Reflection treats properties as hide-by-name-and-signature. See note 2 below.
Method No Yes. A method (both virtual and non-virtual) can be hide-by-name or hide-by-name-and-signature.
Nested Type No No
Property Not applicable The common type system rule is that the inheritance is the same as that of the methods that implement the property. Reflection treats properties as hide-by-name-and-signature. See note 2 below.
  1. Hide-by-name-and-signature considers all of the parts of the signature, including custom modifiers, return types, parameter types, sentinels, and unmanaged calling conventions. This is a binary comparison.
  2. For reflection, properties and events are hide-by-name-and-signature. If you have a property with both a get and a set accessor in the base class, but the derived class has only a get accessor, the derived class property hides the base class property, and you will not be able to access the setter on the base class.
  3. Custom attributes are not part of the common type system.

The following BindingFlags filter flags can be used to define which fields to include in the search:

  • You must specify either BindingFlags.Instance or BindingFlags.Static in order to get a return.
  • Specify BindingFlags.Public to include public fields in the search.
  • Specify BindingFlags.NonPublic to include non-public fields (that is, private and protected fields) in the search.
  • Specify BindingFlags.FlattenHierarchy to include static members up the hierarchy.

The following BindingFlags modifier flags can be used to change how the search works:

  • BindingFlags.IgnoreCase to ignore the case of name.
  • BindingFlags.DeclaredOnly to search only the fields declared on the Type, not fields that were simply inherited.

See System.Reflection.BindingFlags for more information.

If the requested type is non-public and the caller does not have ReflectionPermission to reflect non-public objects outside the current assembly, this method returns a null reference (Nothing in Visual Basic).

Example

[Visual Basic, C#, C++] The following example gets the Type object for the specified class, obtains the FieldInfo object for the field that matches the specified binding flags, and displays the value of the field.

[Visual Basic] 

Imports System
Imports System.Reflection
Imports System.Security
Imports Microsoft.VisualBasic

Public Class MyFieldClassA
    Public myField As String = "A Field"

    Public Property Field() As String
        Get
            Return myField
        End Get
        Set(ByVal Value As String)
            If myField <> value Then
                myField = value
            End If
        End Set
    End Property
End Class 'MyFieldClassA

Public Class MyFieldClassB
    Public myField As String = "B Field"

    Public Property Field() As String
        Get
            Return myField
        End Get
        Set(ByVal Value As String)
            If myField <> value Then
                myField = value
            End If
        End Set
    End Property
End Class 'MyFieldClassB


Public Class MyFieldInfoClass

    Public Shared Sub Main()
        Try
            Dim myFieldObjectB As New MyFieldClassB()
            Dim myFieldObjectA As New MyFieldClassA()

            Dim myTypeA As Type = Type.GetType("MyFieldClassA")
            Dim myFieldInfo As FieldInfo = myTypeA.GetField("myField")

            Dim myTypeB As Type = Type.GetType("MyFieldClassB")
            Dim myFieldInfo1 As FieldInfo = myTypeB.GetField("myField", BindingFlags.Public Or BindingFlags.Instance)

            Console.WriteLine("The value of the field is : {0} ", myFieldInfo.GetValue(myFieldObjectA))
            Console.WriteLine("The value of the field is : {0} ", myFieldInfo1.GetValue(myFieldObjectB))
        Catch e As SecurityException
            Console.WriteLine("An exception has occurred: ")
            Console.WriteLine(("Message :" + e.Message))
        Catch e As ArgumentNullException
            Console.WriteLine("An exception has occurred: ")
            Console.WriteLine(("Message :" + e.Message))
        Catch e As Exception
            Console.WriteLine("An exception has occurred: ")
            Console.WriteLine(("Message :" + e.Message))
        End Try
    End Sub 'Main
End Class 'MyFieldInfoClass


[C#] 

using System;
using System.Reflection;
using System.Security;

public class MyFieldClassA
{
    public string field = "A Field";
    public string Field
    {
        get
        {
            return field;
        }
        set
        {
            if(field!=value)
            {
                field=value;
            }
        }
    }
}
public class MyFieldClassB
{
    public string field = "B Field";
    public string Field 
    {
        get
        {
            return field;
        }
        set
        {
            if(field!=value)
            {
                field=value;
            }
        }
    }
}

public class MyFieldInfoClass
{
    public static void Main()
    {
        try
        {
            MyFieldClassB myFieldObjectB = new MyFieldClassB();
            MyFieldClassA myFieldObjectA = new MyFieldClassA();
            Type myTypeA = Type.GetType("MyFieldClassA");
            FieldInfo myFieldInfo = myTypeA.GetField("field");
            Type myTypeB = Type.GetType("MyFieldClassB");
            FieldInfo myFieldInfo1 = myTypeB.GetField("field", BindingFlags.Public | BindingFlags.Instance);
            Console.WriteLine("The value of the field is : {0} ", myFieldInfo.GetValue(myFieldObjectA));
            Console.WriteLine("The value of the field is : {0} ", myFieldInfo1.GetValue(myFieldObjectB));
        }
        catch(SecurityException e)
        {
            Console.WriteLine("Exception Raised!");
            Console.WriteLine("Message :"+e.Message);
        }
        catch(ArgumentNullException e)
        {
            Console.WriteLine("Exception Raised!");
            Console.WriteLine("Message :"+e.Message);
        }
        catch(Exception e)
        {
            Console.WriteLine("Exception Raised!");
            Console.WriteLine("Message :"+e.Message);
        }
    }
}

[C++] 

#using <mscorlib.dll>

using namespace System;
using namespace System::Reflection;
using namespace System::Security;

public __gc class MyFieldClassA {
public:
   String* field;
   MyFieldClassA(){
      field = S"A Field";
   }
   __property String* get_Field() {

      return field;

   }
   __property void set_Field(String* value) {

      if (field!=value) {
         field=value;

      }
   }
};
public __gc class MyFieldClassB {
public:
   String* field;
   MyFieldClassB() {
      field = S"B Field";
   }
   __property String* get_Field() {

      return field;

   }
   __property void set_Field(String* value) {

      if (field!=value) {
         field=value;

      }
   }
};

int main() {
   try {
      MyFieldClassB* myFieldObjectB = new MyFieldClassB();
      MyFieldClassA* myFieldObjectA = new MyFieldClassA();
      Type*  myTypeA = Type::GetType(S"MyFieldClassA");
      FieldInfo*  myFieldInfo = myTypeA->GetField(S"field");
      Type*  myTypeB = Type::GetType(S"MyFieldClassB");
      FieldInfo*  myFieldInfo1 = myTypeB->GetField(S"field", static_cast<BindingFlags>(BindingFlags::Public | BindingFlags::Instance));
      Console::WriteLine(S"The value of the field is : {0} ", myFieldInfo->GetValue(myFieldObjectA));
      Console::WriteLine(S"The value of the field is : {0} ", myFieldInfo1->GetValue(myFieldObjectB));
   } catch (SecurityException* e) {
      Console::WriteLine(S"Exception Raised!");
      Console::WriteLine(S"Message : {0}", e->Message);
   } catch (ArgumentNullException* e) {
      Console::WriteLine(S"Exception Raised!");
      Console::WriteLine(S"Message : {0}", e->Message);
   } catch (Exception* e) {
      Console::WriteLine(S"Exception Raised!");
      Console::WriteLine(S"Message : {0}", e->Message);
   }
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework, Common Language Infrastructure (CLI) Standard

.NET Framework Security: 

See Also

Type Class | Type Members | System Namespace | Type.GetField Overload List | FieldInfo | String | BindingFlags | DefaultBinder | ReflectionPermission | GetFields

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