Activerecord caching / association problem


I’ve 2 models with a belongs_to / has_many relationship - e.g. Users
has_many Orders.
The problem I have seems related to activerecord caching (which I’m
not 100% clear on).

ex1 :
user = User.create
user.orders.each … # => (no orders, as expected)
user.orders.each … # => (still no orders this time)

Changing the 2nd loop to “user.orders(true).each” fixed it, so I guess
it’s related to caching.

ex2 :
user = User.create
user.orders.count # => 0
user.orders.count # => 1

Strangely, this works, which seems inconsistent with the earlier

Is this expected behaviour, or a bug ?
Should the cache be invalidated on order create ?
What’s the recommended way to fix this ? Just remember to use (true)
sometimes, or can I fix it in the models,
so the app code doesn’t need to worry about it. E.g. is it possible to
invalidate the user and order caches
when a new associated order is created ?


It is not inconsistent behavior.
user.orders.count will fire a count query on your database and will
the result. You can check your log to verify this.
If you use ‘size’ instead of ‘count’, then it will should give you 0
the times.

This may not be the best solution, but you can probably do this:
user.orders << Order.create
instead of user.orders.create