validates_presence_of :user_id
will test if there is a value for self.user_id regardless of whether
there is a valid user with that id on the database.
If you’re going to use :user_id then you should include
validates_associated :user to check the user is valid
validates_presence_of :user will check that the associated user is a
valid record.
validates_presence_of :user_id only tests that there is a value for
user_id
with this method, user_id could be any integer, not necessarily a
valid user.
validates_presence_of :user will also check that the user is a valid
record on the database.
That clear it up?
so validates_presence_of :user does the same like the combination of
validates_presence_of :user_id and validates_associated :user… right?
thanks for the explanation.