Question

I have a question about rails and how its relationships query builder, specifically how camel case is converted for the related calls.

Relevant Code

class CustomerPlan < ActiveRecord::Base
  attr_accessible :customer_id, :plan_id, :startDate, :user_id

  has_many :planActions
end

class PlanAction < ActiveRecord::Base
  attr_accessible :actionType_id, :customerPlan_id, :notes, :timeSpent

  belongs_to :customerPlan
  belongs_to :actionType
end

The getters and setters work just fine, such as plan_action.actionType.name will correctly pull from the related model. However customer_plan.planActions.each returns the error:

SQLite3::SQLException: no such column: plan_actions.customer_plan_id: 
  SELECT "plan_actions".* 
    FROM "plan_actions"  
    WHERE "plan_actions"."customer_plan_id" = 1

The column is defined in the database as customerPlan_id, was I just wrong to use this? It works for every other call, all my other relationships work fine. Even PlanAction -> CustomerPlan.

I ran through all the docs, and searched about every other source I know of. It would be simple enough to change my columns, I just want to know what’s going on here.

Thank you for your time!

---

A quick fix for this is to just explicitly set the foreign_key.

has_many :planActions, :foreign_key => "customerPlan_id", :class_name => "PlanAction"

Still, I think I am missing some model naming convention somewhere, just can’t seem to figure out what.

Answer 1

The Rails convention for DB column names is to use lowercase letters with words separated by an underscore (e.g. author_id, comments_count, updated_at, etc).

I would highly recommend that you stick to the Rails conventions. This would make your life much easier. To change it to the rails convention, simply create a migration to rename the column to the appropriate style.

However, if you do want to use a custom style for the column name, rails provides the :foreign_key option in the has_many relationship to specify the expected foreign column name:

class CustomerPlan < ActiveRecord::Base
  has_many :plan_actions, :foreign_key => 'customerPlan_id'
end

You can also use the alias_attribute macro to alias the column name, if you’d like to use a different model attribute name than the actual DB column name. But as I mentioned, I would recommend sticking to the rails convention as much as possible. You’ll thank me later.