HABTM association between models named with underscore

Question

I have got the following problem: My Rails app has many models, but I have a problem with the association between two of them:

class RedArticle < ActiveRecord::Base
  has_and_belongs_to_many :red_sections
end

class RedSection < ActiveRecord::Base
  has_and_belongs_to_many :red_articles
end

Seems to be a standard setup. But when I test the association for example with

RedArticle.first.red_sections

Then I get the following error:

ActiveRecord::StatementInvalid: Mysql2::Error: Table 'clubago.red_articles_sections' doesn't exist: SHOW FULL FIELDS FROM red_articles_sections

So my Rails looks for a table called red_articles_sections instead of red_articles_red_sections (which exists in my database). Does somebody know where this Problem comes from? I tried to rename the database to red_articles_sections and it worked, but I don't think that this is a good solution.

score 0 · Accepted Answer · answered Jul 27 '15 at 18:10

will this help

class RedArticle < ActiveRecord::Base
 has_and_belongs_to_many :red_sections, join_table: "red_articles_red_sections"
end


class RedSection < ActiveRecord::Base
  has_and_belongs_to_many :red_articles, join_table: "red_articles_red_sections"
end

Reference: http://apidock.com/rails/ActiveRecord/Associations/ClassMethods/has_and_belongs_to_many (options)

score 0 · Answer 2 · edited May 23 '17 at 11:43

This is on purpose, actually. The Rails docs explain it:

If your tables share a common prefix, it will only appear once at the beginning. For example, the tables “catalog_categories” and “catalog_products” generate a join table name of “catalog_categories_products”.

So, your quick fix was correct. However, my personal recommendation would be to drop the Red prefix from both of your models -- unless you have a different model named Article in your schema somewhere, does the Red really add anything?

Athar's solution would also work, if you want to keep the old join table name.

HABTM association between models named with underscore

2 Answers2