has many, belongs to relationship allowing duplicates...

rubyonrails-talk
1

Hi all,

I have a couple of tables setup as follows:

(1) User table (general user info)

(2) Subsriptions table id user_id <- links to User.id subscriber_id <- links to User.id

Basically a user can have one or more subscribers. Subscribers being other users.

User has the following:

has_many :subscribers,         :class_name => 'Subscription'

Subscription model has:

belongs_to :user,       :class_name => 'User'

Is there anyway that I can setup a relationship like this, with these two tables, having a user that has subscribers, but disallow duplicates in the subscriptions table?

Because when I do something line the following:

u = User.find(1) s = Subscription.new s.user_id = 1 s.subscriber_id = 3 u.subscribers << 2

I end up with the following records in the subscriptions table:

id user_id subscriber_id 1 1 3 2 1 3

Record with id = 1 was there before the above code was run. How can I set thiings up so that if I add a subscriber that already exists for a particular user, it doesn't add a duplicate record. Would be nice if it doesn't complain about trying to add one either and just does nothing if it's already there. Maybe that's asking too much?

Any help would be greatly appreciated.

Thanks in advance.

Cheers, Diego

2

Diego,

Take a look at validates_uniqueness_of. Something like this should get you started:

class Subscription < ActiveRecord::Base   validates_uniqueness_of :user_id, :scope => :subscriber_id end

Validations will prevent a record from being saved and attach error information to the object. What you do with that information is your decision.

Aaron

3

Hi Arron,

Thanks for the pointers. I'll follow along and try these out. Appreciate it!

Cheers, Diego

4

I have a couple of tables setup as follows:

(1) User table (general user info)

(2) Subsriptions table id user_id <- links to User.id subscriber_id <- links to User.id

Basically a user can have one or more subscribers. Subscribers being other users.

User has the following:

has_many :subscribers,         :class_name => 'Subscription'

Subscription model has:

belongs_to :user,       :class_name => 'User'

Is there anyway that I can setup a relationship like this, with these two tables, having a user that has subscribers, but disallow duplicates in the subscriptions table?

has_many has a :uniq option that might help you out...

:uniq - if set to true, duplicates will be omitted from the collection. Useful in conjunction with :through.