AF SDK Reference

AFChangedEventArgs Class

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AFChangedEventArgs Class

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Last UpdatedNov 18, 2025
5 minute read

Provides data for the Changed event.

Inheritance Hierarchy

SystemObject
  SystemEventArgs
    OSIsoft.AFAFEventArgs
      OSIsoft.AFAFChangedEventArgs

Namespace: OSIsoft.AF
Assembly: OSIsoft.AFSDK (in OSIsoft.AFSDK.dll) Version: 3.1.1.1182

Syntax

public sealed class AFChangedEventArgs : AFEventArgs, 
	IEquatable<AFChangedEventArgs>

Public NotInheritable Class AFChangedEventArgs
	Inherits AFEventArgs
	Implements IEquatable(Of AFChangedEventArgs)

Dim instance As AFChangedEventArgs

public ref class AFChangedEventArgs sealed : public AFEventArgs, 
	IEquatable<AFChangedEventArgs^>

[<SealedAttribute>]
type AFChangedEventArgs =  
    class
        inherit AFEventArgs
        interface IEquatable<AFChangedEventArgs>
    end

The AFChangedEventArgs type exposes the following members.

Constructors

	Name	Description
	AFChangedEventArgs(AFChangeAction)	Initializes a new instance of the AFChangedEventArgs class for an object change action.
	AFChangedEventArgs(AFChangeAction, AFIdentity, Guid, Guid)	Initializes a new instance of the AFChangedEventArgs class for a sub-object change action.

Properties

	Name	Description
	Action	Gets an action that specifies how the object changed.
	ID	The ID of the sub-object that changed. (Overrides AFEventArgsID.)
	Identity	The Identity of the sub-object that changed.
	IsSubObjectEvent	Indicates if the arguments represent a sub-object event.
	ParentID	The ID of the parent object that changed.

Methods

	Name	Description
	Equals(Object)	Determines whether the specified Object is equal to the current object. (Overrides ObjectEquals(Object).)
	Equals(AFChangedEventArgs)	Indicates whether the current object is equal to another object of the same type.
	FindObject	Retrieves the AFObject associated with the event.
	GetHashCode	Gets the hash code for this instance of the object which is suitable for use in hashing algorithms and data structures like a hash table. (Overrides ObjectGetHashCode.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	ToString	Returns a String that represents the current object. (Overrides ObjectToString.)

Operators

	Name	Description
	Equality	The equality operator (==) compares its operands to determine if they are equal.
	Inequality	The inequality operator (!=) compares its operands to determine if they are not equal.

Remarks

A Changed event is raised when something about the object or one of its sub-objects has been modified. For example, this event is raised when the description of the object is modified. See AFChangeAction for a description of what will cause an event to be raised for each of the action values.

When the object has sub-objects that also implement the IAFChangedEvent interface, then it will receive SubObjectAdd, SubObjectRemove, and SubObjectRefresh events for these sub-objects when items are added or removed from this sub-collection. To receive events on changes to existing sub-objects (e.g. changes to its Description property), you must add an event handler to the sub-object's Changed event.

The AFDatabase.Changed event will also receive SubObjectAdd, SubObjectRemove, SubObjectChange, and SubObjectRefresh events for IAFTransactable objects owned by the AFDatabase. For example, if an AFReferenceType is added the AFDatabase will receive a SubObjectAdd event. If the description of an AFElement is modified, then the AFDatabase will receive a SubObjectChange event.

Similarly, the PISystem.Changed event will also receive SubObjectAdd, SubObjectRemove, SubObjectChange, and SubObjectRefresh events for IAFTransactable objects owned by the PISystem.

AF SDK Reference