Rails get column names from all tables after join

Question

I'm trying to get the column names from several tables having performed a join to combine them.

I tried just doing the following:

User.joins(:user_account, :user_file, :user_education).column_names 

but this is only returning the column names from User, as if I had just done the following:

User.column_names 

Does anyone know how to get all of the column names from a join? It seems that this isn't often needed because there doesn't seem to be much information about it online. I need it in order to validate user params.

Thanks!

EDIT:

column names in User table:

["id", "status", "accepted_terms", "created_at", "updated_at", "email", "encrypted_password", "reset_password_token", "reset_password_sent_at", "remember_created_at", "sign_in_count", "current_sign_in_at", "last_sign_in_at", "current_sign_in_ip", "last_sign_in_ip", "confirmation_token", "confirmed_at", "confirmation_sent_at", "unconfirmed_email", "provider", "uid"]

column names in User_account table:

 ["first_name", "last_name", "phone_number", "address"]

I want to be able to get an entire list of column names, i.e.

["id", "status", "accepted_terms", "created_at", "updated_at", "email", "encrypted_password", "reset_password_token", "reset_password_sent_at", "remember_created_at", "sign_in_count", "current_sign_in_at", "last_sign_in_at", "current_sign_in_ip", "last_sign_in_ip", "confirmation_token", "confirmed_at", "confirmation_sent_at", "unconfirmed_email", "provider", "uid", "first_name", "last_name", "phone_number", "address"]

What method do I need to get exactly that list? I have tried

User.joins(:user_account).column_names

but this just gives me the first set of column names, i.e. the ones in just the user table (not the ones in the user account table).

Answer 1

You can simply do this:

User.column_names + UserAccount.column_names

and so on. Rails retrieves column names from ActiveRecord class, not from SQL relation.

UPD. Or more idiomatic

[User, UserAccount, UserFile, UserEducation].flat_map(&:column_names).uniq