As we know the model can associate other model through the foreign key which is assigned or with an “_id” suffix by default. But can we define functional foreign key by ourselves ?
eg: class Condition < ActiveRecord::Base belongs_to :city_info, foreign_key: "substring_index(the_city,',',1)" end class CityInfo < ActiveRecord::Base end >> Condition.includes(:city_info).references(:city_info).last >> Mysql2::Error: Unknown column 'conditions.substring_index(the_city,',',1)' >> in 'on clause': SELECT ..... >> ......`conditions`.`substring_index(the_city,',',1)` ORDER BY >> `conditions`.`id` DESC LIMIT 1 It's wrong. How can we achieve this. I want to retrieve many conditions object, each associates with its first city_info by ActiveRecord with generating a single sql (not n+1 ) like this: select * from conditions left outer join city_info on convert(substring_index(conditions.the_city,',',1), unsigned integer) = city_info.id ref: https://github.com/rails/rails/issues/14481 -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Core" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/rubyonrails-core. For more options, visit https://groups.google.com/d/optout.
