Get ID of the object saved with association

Here is my scenario: I have three models Subscriber, Subscription, Plan, with has_many :through relationship between Subscriber and Plans. A subscriber can have multiple plans with one active plan. Whenever a subscriber selects a plan I save it using accepts_nested_attributes_for :subscriptions. I get one plan from the form. Now my problem is I want to get the ID of t开发者_Go百科he record created in subscriptions table.

Currently I am retrieving it by finding all subscriptions for the subscriber ordered descending on date created and taking first from the resultset. Is there any direct method to do this?

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Suppose you have this in controller:

 @subscriber = Subscriber.find(params[:id])
 @subscriber.update_attributes(params[:subscriber])

then you can find last subscription id with:

 @subscriber.subscriptions.order("created_at DESC").first.id

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@subscriber.subscriptions.last

is a cheaper solution. otherwise you could write a custom method in your model.