ruby - Join type in ActiveRecord has_one Relationship -

just getting started activerecord (in sinatra app). trying port existing queries ar getting little stuck.

if have has_one relation users , profiles (using legacy tables unfortunately)

class user < activerecord::base      self.table_name = "systemusers"     self.primary_key = "user_id"      has_one :profile, class_name: 'profile', foreign_key: 'profile_user_id' end  class profile < activerecord::base      self.table_name = "systemuserprofiles"     self.primary_key = "profile_id"      belongs_to :user, class_name: "user", foreign_key: 'user_id'  end 

if want query users profile using inner join user_age field profiles using 1 query can it?

for example (just added .first reduce code looping through users profiles)

user = user.all(:joins => :profile).first user.profile.user_age 

gives me correct data , uses inner join first query issues second query profile data

it gives depreciated warning , suggests use load, tried won't use inner join.

similar case with

user = user.joins(:profile).first user.profile.user_age 

i inner join query each user row.

i have tried includes

user = user.includes(:profile).first user.profile.user_age 

this lazy loads profile , reduce number of queries in loop, think pull users without profile too

i tried reference

user = user.includes(:profile).references(:profile).first user.profile.user_age 

this gives me correct data , reduces queries 1 uses left join

i have not quite grasped , trying achieve thats not do-able, figured might either need use includes , check nil profiles inside loop or use joins , accept additional query each row.

thought i'd check incase missing obvious.

cheers

pat.

profile should have 1 user. so, profile.first.user_age first user profile. going user approach did,

user.find { |u| u.profile }.profile.user_age 

user.find { |u| u.profile } returns first user true value.

to query user profiles , user_ages. assuming profiles has user_id , should case.

 profile.pluck(:user_age) 

this checks presence of user_id if save profiles without user id. where.not new feature in activerecord, check version.

 profile.where.not(user_id: nil).pluck(:user_age)