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ObjectStateManager Class

Maintains object state and identity management for entity type instances and relationship instances.

System.Object
  System.Data.Objects.ObjectStateManager

Namespace:  System.Data.Objects
Assembly:  System.Data.Entity (in System.Data.Entity.dll)

'Declaration
Public Class ObjectStateManager

The ObjectStateManager type exposes the following members.

  NameDescription
Public methodObjectStateManagerInitializes a new instance of the ObjectStateManager class.
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  NameDescription
Public propertyMetadataWorkspaceGets the MetadataWorkspace associated with this state manager.
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  NameDescription
Public methodChangeObjectStateChanges state of the ObjectStateEntry for a specific object to the specified entityState.
Public methodChangeRelationshipState(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.
Public methodChangeRelationshipState(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.
Public methodChangeRelationshipState(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.
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetObjectStateEntriesReturns a collection of ObjectStateEntry objects for objects or relationships with the given state.
Public methodGetObjectStateEntry(EntityKey)Returns an ObjectStateEntry for the object or relationship entry with the specified key.
Public methodGetObjectStateEntry(Object)Returns an ObjectStateEntry for the specified object.
Public methodGetRelationshipManagerReturns the RelationshipManager that is used by the specified object.
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodTryGetObjectStateEntry(EntityKey, ObjectStateEntry)Tries to retrieve the corresponding ObjectStateEntry for the object or relationship with the specified EntityKey.
Public methodTryGetObjectStateEntry(Object, ObjectStateEntry)Tries to retrieve the corresponding ObjectStateEntry for the specified Object.
Public methodTryGetRelationshipManagerReturns the RelationshipManager that is used by the specified object.
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  NameDescription
Public eventObjectStateManagerChangedOccurs when entities are added to or removed from the state manager.
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ObjectStateManager 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 ObjectStateManager 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 ObjectStateManager 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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5 SP1

.NET Framework Client Profile

Supported in: 4

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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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