t.references usage

rubyonrails-talk
1

While I'm not currently using the whole rails environment, I may utilize the framework in the future. In the meantime, I'm not clear on the syntax for establishing a foreign key relationship for an active record association using "t.references" or "t.belongs_to":

thufir@ARRAKIS:~/projects/rss2mysql$ thufir@ARRAKIS:~/projects/rss2mysql$ rake migrate (in /home/thufir/projects/rss2mysql) == CreateSubscribers: migrating

2

3 things came to my mind as I read your post...

1) Upgrade to a later version of Rails. You don't say what version you are using, but the convention of migrations named NNNN_some_name changed to YYYYMMDDHHMMSS_some_name about a year(ish) ago when I first started learning about Rails.

2) I wonder if you have a pluralization problem and if yuo should change your CreateSubscriptions class to use

     t.references subscriber

instead of

     t.references subscribers. In general, I have learned that a "thing" model "has_many :somethings" (note the plural) while the Something model would "belongs_to :thing" (note the singular).

3) I also wonder why you commented out the creation of the primary key for your Subscriptions table, although that is not likely to be your problem.

--wpd

3

thufir@ARRAKIS:~/projects/rss2mysql$

is there an error with migration, or in how it's used?

well much like you write t.column :subscriber_id and not t.column subscriber_id, you need to write t.references :subscribers

Fred

4

I went with t.references :subscriber as that worked better with my script:

thufir@ARRAKIS:~/projects/rss2mysql$ thufir@ARRAKIS:~/projects/rss2mysql$ cat db/ migrate/0030_create_subscriptions.rb class CreateSubscriptions < ActiveRecord::Migration   def self.up     create_table :subscriptions do |t|       #t.column :subscriber_id, :integer #, :null => false       t.references :subscriber       t.column :subscription, :string     end   end

  def self.down     drop_table :subscriptions   end end

thufir@ARRAKIS:~/projects/rss2mysql$

which is correct, subscriber or subscribers?

-Thufir

5

While I'm not currently using the whole rails environment, I may utilize the framework in the future.

[...]

1) Upgrade to a later version of Rails.

I may use the framework at a later point, but for now am just using Active Record.

2) I wonder if you have a pluralization problem and if yuo should change your CreateSubscriptions class to use

     t.references subscriber

instead of

     t.references subscribers. In general, I have learned that a "thing" model "has_many :somethings" (note the plural) while the Something model would "belongs_to :thing" (note the singular).

Yes, I seem to be having this problem, but I *seem* to have worked it out (see seperate post).

3) I also wonder why you commented out the creation of the primary key for your Subscriptions table, although that is not likely to be your problem.

Oh, only because rather than create it manually, I wanted to use this "references" feature.

-Thufir

6

subscriber (that was just a typo on my behalf - the main thing is that you need to be passing a string or symbol)

Fred