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11/18/2011

MissingFieldException Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

The exception that is thrown when there is an attempt to dynamically access a field that does not exist.

Inheritance Hierarchy

System.Object
  System.Exception
    System.SystemException
      System.MemberAccessException
        System.MissingMemberException
          System.MissingFieldException

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

Syntax

'Declaration
<ComVisibleAttribute(True)> _
Public Class MissingFieldException _
    Inherits MissingMemberException

[ComVisibleAttribute(true)]
public class MissingFieldException : MissingMemberException

The MissingFieldException type exposes the following members.

Constructors

	Name	Description
	MissingFieldException()	Initializes a new instance of the MissingFieldException class.
	MissingFieldException(String)	Initializes a new instance of the MissingFieldException class with a specified error message.
	MissingFieldException(String, Exception)	Initializes a new instance of the MissingFieldException class with a specified error message and a reference to the inner exception that is the cause of this exception.

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Properties

	Name	Description
	Data	Gets a collection of key/value pairs that provide additional user-defined information about the exception. (Inherited from Exception.)
	HResult	Gets or sets HRESULT, a coded numerical value that is assigned to a specific exception. (Inherited from Exception.)
	InnerException	Gets the Exception instance that caused the current exception. (Inherited from Exception.)
	Message	Gets the text string showing the signature of the missing field, the class name, and the field name. This property is read-only. (Overrides MissingMemberException.Message.) In Silverlight for Windows Phone, this member is overridden by Message. In XNA Framework, this member is overridden by Message.
	StackTrace	Gets a string representation of the frames on the call stack at the time the current exception was thrown. (Inherited from Exception.)

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Methods

	Name	Description
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetBaseException	When overridden in a derived class, returns the Exception that is the root cause of one or more subsequent exceptions. (Inherited from Exception.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the runtime type of the current instance. (Inherited from Exception.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ToString	Creates and returns a string representation of the current exception. (Inherited from Exception.)

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Remarks

Normally a compilation error is generated if code attempts to access a nonexistent member of a class. MissingFieldException is designed to handle cases where an attempt is made to dynamically access a renamed or deleted field of an assembly that is not referenced by its strong name. The MissingFieldException is thrown when code in a dependent assembly attempts to access a missing field in an assembly that was modified.

MissingFieldException uses the HRESULT COR_E_MISSINGFIELD, that has the value 0x80131511.

For a list of initial property values for an instance of MissingFieldException, see the MissingFieldException constructors.

Examples

This example shows what happens if you attempt to use reflection to call a method that does not exist and access a field that does not exist. The application recovers by catching the MissingMethodException, MissingFieldException, and MissingMemberException.

Note:
To run this example, see Building Examples That Use a Demo Method and a TextBlock Control.

Imports System.Reflection

Public Class Example
   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Try
         ' Attempt to call a static DoSomething method defined in the Example class.
         ' However, because the Example class does not define this field, 
         ' a MissingFieldException is thrown.
         GetType(Example).InvokeMember("DoSomething", BindingFlags.Static Or BindingFlags.InvokeMethod, _
                                    Nothing, Nothing, Nothing)
      Catch e As MissingMethodException
         ' Show the user that the DoSomething method cannot be called.
         outputBlock.Text += String.Format("Unable to call the DoSomething method: {0}", e.Message) & vbCrLf
      End Try
      Try
         ' Attempt to access a static AField field defined in the Example class.
         ' However, because the Example class does not define this field, 
         ' a MissingFieldException is thrown.
         GetType(Example).InvokeMember("AField", BindingFlags.Static Or BindingFlags.SetField, _
                                    Nothing, Nothing, New [Object]() {5})
      Catch e As MissingFieldException
         ' Show the user that the AField field cannot be accessed.
         outputBlock.Text += String.Format("Unable to access the AField field: {0}", e.Message) & vbCrLf
      End Try
      Try
         ' Attempt to access a static AnotherField field defined in the Example class.
         ' However, because the Example class does not define this field, 
         ' a MissingFieldException is thrown.
         GetType(Example).InvokeMember("AnotherField", BindingFlags.Static Or BindingFlags.GetField, _
                                    Nothing, Nothing, Nothing)
      Catch e As MissingMemberException
         ' Notice that this code is catching MissingMemberException which is the  
         ' base class of MissingMethodException and MissingFieldException.
         ' Show the user that the AnotherField field cannot be accessed.
         outputBlock.Text += String.Format("Unable to access the AnotherField field: {0}", e.Message) & vbCrLf
      End Try
   End Sub
End Class
' This code example produces the following output:
'
' Unable to call the DoSomething method: Method 'App.DoSomething' not found.
' Unable to access the AField field: Field 'App.AField' not found.
' Unable to access the AnotherField field: Field 'App.AnotherField' not found.

using System;
using System.Reflection;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {

      try
      {
         // Attempt to call a static DoSomething method defined in the Example class.
         // However, because the Example class does not define this field, 
         // a MissingFieldException is thrown.
         typeof(Example).InvokeMember("DoSomething", BindingFlags.Static |
             BindingFlags.InvokeMethod, null, null, null);
      }
      catch (MissingMethodException e)
      {
         // Show the user that the DoSomething method cannot be called.
         outputBlock.Text += String.Format("Unable to call the DoSomething method: {0}", e.Message) + "\n";
      }

      try
      {
         // Attempt to access a static AField field defined in the Example class.
         // However, because the Example class does not define this field, 
         // a MissingFieldException is thrown.
         typeof(Example).InvokeMember("AField", BindingFlags.Static | BindingFlags.SetField,
             null, null, new Object[] { 5 });
      }
      catch (MissingFieldException e)
      {
         // Show the user that the AField field cannot be accessed.
         outputBlock.Text += String.Format("Unable to access the AField field: {0}", e.Message) + "\n";
      }

      try
      {
         // Attempt to access a static AnotherField field defined in the Example class.
         // However, because the Example class does not define this field, 
         // a MissingFieldException is thrown.
         typeof(Example).InvokeMember("AnotherField", BindingFlags.Static |
             BindingFlags.GetField, null, null, null);
      }
      catch (MissingMemberException e)
      {
         // Notice that this code is catching MissingMemberException which is the  
         // base class of MissingMethodException and MissingFieldException.
         // Show the user that the AnotherField field cannot be accessed.
         outputBlock.Text += String.Format("Unable to access the AnotherField field: {0}", e.Message) + "\n";
      }
   }
}
// This code example produces the following output:
//
// Unable to call the DoSomething method: Method 'App.DoSomething' not found.
// Unable to access the AField field: Field 'App.AField' not found.
// Unable to access the AnotherField field: Field 'App.AnotherField' not found.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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