Altering the primary key in Rails to be a string

Question

So I've got two models, State and Acquisition. State has_many Acquisitions. I felt like an autoincrementing integer primary key for 51 records was rather silly. So I altered the model for the State to be the PK (State being the two letter abbreviation; I'm not storing the actual state name anywhere:

class State < ActiveRecord::Base     self.primary_key = "state"     has_many :acquisition_histories   end 

The problem is when I created my Acquisition model, it created the foreign key column state_id as an integer. More specifically, the script/generated migration did:

class CreateAcquisitions < ActiveRecord::Migration     def self.up       create_table :acquisitions do |t|         t.date :date         t.string :category         t.text :notes         t.references :state         t.timestamps       end   end end 

I'm assuming that t.references data type sets it to int. The problem is my create method on my Acquisition class is trying to put a state abbreviation into the state_id field on the table acquisitions (and yes, it's called state_id on the database, even though it says :state in the migration script). The method doesn't fail, but it does put a 0 in the state_id field and the records go into the ether.

Answer 1

Though, I agree that this might be more trouble than it's worth considering the extra effort of working against the defaults elsewhere, just in case you actually want to do what you've asked:

Create states migration:

class CreateStatesTable < ActiveRecord::Migration     def change     create_table :states, id: false do |t|       t.string :state, limit: 2       t.string :name       t.index :state, unique: true     end   end end 

states model:

class State < ActiveRecord::Base   self.primary_key = :state end 

Note that before Rails 3.2, this was set_primary_key = :state instead of self.primary_key= see: http://guides.rubyonrails.org/3_2_release_notes.html#active-record-deprecations

Answer 2

if you find yourself here... leave as quickly as you can and go to: Using Rails, how can I set my primary key to not be an integer-typed column?