Type.GetField Method (String, BindingFlags)

July 28, 2014

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

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

public abstract FieldInfo GetField(
	string name,
	BindingFlags bindingAttr
)

Parameters

name
Type: System.String
The String containing the name of the data field to get.
bindingAttr
Type: System.Reflection.BindingFlags
A bitmask comprised of one or more BindingFlags that specify how the search is conducted.
-or-
Zero, to return null.

Return Value

Type: System.Reflection.FieldInfo
A FieldInfo object representing the field that matches the specified requirements, if found; otherwise, null.

Implements

IReflect.GetField(String, BindingFlags)

ExceptionCondition
ArgumentNullException

name is null.

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.

Notes:

  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 public and protected static members up the hierarchy; private static members in inherited classes are not included.

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 current Type represents a constructed generic type, this method returns the FieldInfo with the type parameters replaced by the appropriate type arguments.

If the current Type represents a type parameter in the definition of a generic type or generic method, this method searches the fields of the class constraint.

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.



using System;
using System.Reflection;

public class MyFieldClassA
{
   public string Field = "A Field";
}

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

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      MyFieldClassB myFieldObjectB = new MyFieldClassB();
      MyFieldClassA myFieldObjectA = new MyFieldClassA();

      Type myTypeA = typeof(MyFieldClassA);
      FieldInfo myFieldInfo = myTypeA.GetField("Field");

      Type myTypeB = typeof(MyFieldClassB);
      FieldInfo myFieldInfo1 = myTypeB.GetField("field",
          BindingFlags.NonPublic | BindingFlags.Instance);

      outputBlock.Text += String.Format("The value of the public field is: '{0}'\n",
          myFieldInfo.GetValue(myFieldObjectA));

      try
      {
         // In Windows Phone, the value of a private field cannot be accessed
         // by using reflection.
         outputBlock.Text += String.Format("The value of the private field is: '{0}'\n",
            myFieldInfo1.GetValue(myFieldObjectB));
      }
      catch (Exception ex)
      {
         outputBlock.Text += ex.GetType().Name + " occurred: " + ex.Message;
      }
   }
}

/* This code produces output similar to the following:

The value of the public field is: 'A Field'
FieldAccessException occurred: MyFieldClassB.myField
 */


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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