CODEWITHSUNDEEP
ruby-on-rails
CodeSmith
CodeSmith

Reputation: 2243

How to use pluck to get attribute from model associated with class_name

I have an Entry model which belongs to an Organization model...twice. 

class Entry < ActiveRecord::Base
  belongs_to :organization
  belongs_to :temp_organization, class_name: "Organization"
end

I'm trying to write a single AR query that pulls off the associated organization and temp_organization name using pluck.

Entry
  .includes(:organization, :temp_organization)
  .pluck('organizations.name', 'temp_organizations.name')

This crashes with the following error:

ActiveRecord::StatementInvalid (PG::UndefinedTable: ERROR:  missing FROM-clause  entry for table "temp_organizations"

Which makes sense - there is no temp_organizations table since that association is managed through the regular organizations table.

How do I get pluck to pull the temp_organization name?

Upvotes: 2

Views: 484

Answers (2)

Priyank Gupta
Priyank Gupta

Reputation: 421

Try using,

Entry
  .includes(:organization, :temp_organization)
  .references(:organization, :temp_organization)
  .pluck('organizations.name', 'entries_temp_organizations.name')

Upvotes: 2

Mickey Sheu
Mickey Sheu

Reputation: 768

So with multiple joins to the same table, AR does some magic and renames the table, which is why you can't pull up the right table name.

You can check what the table name is by looking at the generated sql: 

Entry.includes(:organization, :temp_organization).to_sql

You should get something like: 

...INNER JOIN \"organizations\" \"entries_temp_organizations\" ON \"entries_temp_organizations\"...

I would suspect the table name is 'entries_temp_organizations' (following AR rule of alphabetical ordering for join tables). A pluck with the correct table name should do the trick.

Upvotes: 1

Related Questions