Maintains object state and identity management for entity type instances and relationship instances.
Assembly: System.Data.Entity (in System.Data.Entity.dll)
Thetype exposes the following members.
|ChangeObjectState||Changes state of the ObjectStateEntry for a specific object to the specified entityState.|
|ChangeRelationshipState(Object, Object, String, EntityState)||Changes the state of the relationship between two entity objects that is specified based on the two related objects and the name of the navigation property.|
|ChangeRelationshipState(Object, Object, String, String, EntityState)||Changes the state of the relationship between two entity objects that is specified based on the two related objects and the properties of the relationship.|
|ChangeRelationshipState(Of TEntity)(TEntity, Object, Expression(Of Func(Of TEntity, Object)), EntityState)||Changes the state of the relationship between two entity objects that is specified based on the two related objects and a LINQ expression that defines the navigation property.|
|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 it is reclaimed by garbage collection. (Inherited from Object.)|
|GetHashCode||Serves as a hash function for a particular type. (Inherited from Object.)|
|GetObjectStateEntries||Returns a collection of ObjectStateEntry objects for objects or relationships with the given state.|
|GetObjectStateEntry(EntityKey)||Returns an ObjectStateEntry for the object or relationship entry with the specified key.|
|GetObjectStateEntry(Object)||Returns an ObjectStateEntry for the specified object.|
|GetRelationshipManager||Returns the RelationshipManager that is used by the specified object.|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|MemberwiseClone||Creates a shallow copy of the current Object. (Inherited from Object.)|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
|TryGetObjectStateEntry(EntityKey, ObjectStateEntry)||Tries to retrieve the corresponding ObjectStateEntry for the object or relationship with the specified EntityKey.|
|TryGetObjectStateEntry(Object, ObjectStateEntry)||Tries to retrieve the corresponding ObjectStateEntry for the specified Object.|
|TryGetRelationshipManager||Returns the RelationshipManager that is used by the specified object.|
tracks query results, and provides logic to merge multiple overlapping query results. It also performs in-memory change tracking when a user inserts, deletes, or modifies objects, and provides the change set for updates. This change set is used by the change processor to persist modifications.
This class is typically used by ObjectContext and not directly in applications.
These examples are based on the Adventure Works Sales Model.
The following example gets the from the ObjectContext and uses the state manager to access an object in the context.
Dim orderId As Integer = 43680 Using context As New AdventureWorksEntities() Dim objectStateManager As ObjectStateManager = context.ObjectStateManager Dim stateEntry As ObjectStateEntry = Nothing Dim order = (From o In context.SalesOrderHeaders Where o.SalesOrderID = orderId Select o).First() ' Attempts to retrieve ObjectStateEntry for the given EntityKey. Dim isPresent As Boolean = objectStateManager.TryGetObjectStateEntry(DirectCast(order, IEntityWithKey).EntityKey, stateEntry) If isPresent Then Console.WriteLine("The entity was found") End If End Using
The following example uses the TryGetObjectStateEntry(EntityKey, ObjectStateEntry) method on the returned to get an object based on its entity key.
Private Shared Sub ApplyItemUpdates(ByVal originalItem As SalesOrderDetail, ByVal updatedItem As SalesOrderDetail) Using context As New AdventureWorksEntities() context.SalesOrderDetails.Attach(updatedItem) ' Check if the ID is 0, if it is the item is new. ' In this case we need to chage the state to Added. If updatedItem.SalesOrderDetailID = 0 Then ' Because the ID is generated by the database we do not need to ' set updatedItem.SalesOrderDetailID. context.ObjectStateManager.ChangeObjectState(updatedItem, System.Data.EntityState.Added) Else ' If the SalesOrderDetailID is not 0, then the item is not new ' and needs to be updated. Because we already added the ' updated object to the context we need to apply the original values. ' If we attached originalItem to the context ' we would need to apply the current values: ' context.ApplyCurrentValues("SalesOrderDetails", updatedItem); ' Applying current or original values, changes the state ' of the attached object to Modified. context.ApplyOriginalValues("SalesOrderDetails", originalItem) End If context.SaveChanges() End Using End Sub
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.