Session: Deleting Entities
Entities can be marked for deletion by using the delete
method, but will not be removed from the server until saveChanges
is called.
Syntax
<T> void delete(T entity);
void delete(String id);
void delete(String id, String expectedChangeVector);
Parameters | ||
---|---|---|
entity | T |
instance of the entity to delete |
id | String |
ID of the entity to delete |
expectedChangeVector | String |
a change vector to use for concurrency checks |
Example I
Employee employee = session.load(Employee.class, "employees/1");
session.delete(employee);
session.saveChanges();
Concurrency on Delete
If useOptimisticConcurrency is set to 'true' (default 'false'), the delete() method will use loaded 'employees/1' change vector for concurrency check and might throw ConcurrencyException.
Example II
session.delete("employees/1");
session.saveChanges();
Concurrency on Delete
In this overload, the delete() method will not do any change vector based concurrency checks because the change vector for 'employees/1' is unknown.
Information
If entity is not tracked by session, then executing
session.delete("employees/1");
is equal to doing
session.advanced().defer(new DeleteCommandData("employees/1", null));
Change Vector in DeleteCommandData
In this sample the change vector is null - this means that there will be no concurrency checks. A non-null and valid change vector value will trigger a concurrency check.
You can read more about defer operations here.