CODEWITHSUNDEEP
c#entity-framework-4
flesh
flesh

Reputation: 23935

How to correctly update entities in EF4 using POCO and custom ObjectContext?

Using the technique described here I have a simple POCO EF4 model up and running. Saving new and deleting is straightforward (using AddObject() and DeleteObject() respectively). But the only way of updating objects I have found is to retrieve the stored version of the object and manually update its properties with new values from the object being saved. Surely there is a better way?

My ObjectContext is disconnected - in otherwords, I use a new ObjectContext instance for each operation on the model.

Thanks.

Upvotes: 1

Views: 915

Answers (1)

RPM1984
RPM1984

Reputation: 73112

Use the stub technique:

public void UpdateOrder(Order o)
{
   var stub = new Order { Id = o.OrderId }; // create stub with EntityKey
   ctx.Orders.Attach(stub); // attach stub to graph
   ctx.ApplyCurrentValues("Orders", o); // override stub with values.
   ctx.SaveChanges();
}

If the entity is already in the graph, you will get an OSM exception (entity with key already exists).

I counteract this by checking if the object exists in the graph first (TryGetObjectStateEntry) and only attaching if it doesn't.

Upvotes: 4

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