ObjectContext.Detach Method (Object)


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Removes the object from the object context.

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

public void Detach(
	object entity


Type: System.Object

Object to be detached. Only the entity is removed; if there are any related objects that are being tracked by the same ObjectStateManager, those will not be detached automatically.

Exception Condition

The entity is null.


The entity is not associated with this ObjectContext (for example, was newly created and not associated with any context yet, or was obtained through some other context, or was already detached).

Removes the object from the ObjectStateManager. This disables change tracking and identity resolution for that object. For more information, see Attaching and Detaching Objects.

After the Detach method is called, the system will no longer keep references that point to this object and it can be collected by the garbage collector.


Garbage collection can only occur if the user code does not have any references to the detached object.

The following considerations apply when detaching objects:

  • Detach only affects the specific object that is passed to the method. If the object being detached has related objects in the object context, those objects are not detached.

  • Detaching objects does not affect data in the data source.

  • Cascade delete directives and referential constraints are not enforced during a detach operation.

For more information, see Attaching and Detaching Objects.

// This method is called to detach SalesOrderHeader objects and 
// related SalesOrderDetail objects from the supplied object
// context when no longer needed by the application. 
// Once detached, the resources can be garbage collected.
private static void DetachOrders(ObjectContext context,
    SalesOrderHeader order)
        // Detach each item from the collection.
        while (order.SalesOrderDetails.Count > 0)
            // Detach the first SalesOrderDetail in the collection.

        // Detach the order.
    catch (InvalidOperationException ex)

.NET Framework
Available since 3.5
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