Persistence in Entity Framework
There are two scenarios when persisting an entity using EntityFramework, connected and disconnected scenarios.
Connected Scenario: This is when an entity is retrieved from the database and persist is used in the same context. Context object doesn't destroy between entity retrieval and persistence of entities.
Disconnected Scenario: Disconnected scenario is when an entity is retrieved from the database and the changed entities are submitted using the different objects in the context. The following example illustrates disconnected scenario:
As per the above scenario, Context1 is used for read operation and then Context1 is destroyed. Once entities change, the application submits entities using Context2 - a different context object.
Disconnected scenario is complex because the new context doesn't know anything about the modified entity so you will have to instruct the context of what has changed in the entity. In the figure below, the application retrieves an entity graph using Context 1 and then the application performs some CUD (Create, Update, Delete) operations on it and finally, it saves the entity graph using Context 2. Context 2 doesn't know what operation has been performed on the entity graph in this scenario.
Learn how to do the CRUD operation in the connected scenario in the next section.