Query Between Two Tables Using Ruby - mysql

Question

My code is this
contact = UserContact.find(:all,:select=>"distinct app_id,number",:conditions=>"number ='1234'")
arr=[]
contact.each do|c|
arr << c.app_id
end
name=User.find(:all,:conditions=>"id in(#{arr.join(',')}")
I takes two much time Can i do this using join
Thanks

Answer 1

You should do smth like this
User.find(:all, :joins => :user_contacts, :conditions => "user_contacts.number = '1234'")
user should have association. In user.rb should be:
has_many :user_contacts, :foreign_key => :app_id
But it is bad style to name column "app_id" it should be "user_id"(convention over configuration). Renamed it. After rename you can remove ", :foreign_key => :app_id"

Answer 2

Unfortunately you can NOT do "includes" and "select" in the same Active record Query. So this will not work...
contacts = UserContact.includes(:users).where("number = ?", '1234').select(:app_id, :number).uniq
BUT.
FIRST: app_id looks like it should be called "user_id"
SECOND: What version of Rails are you using? You might want to use the "pluck" method if you are using rails 3.2. Hence
user_ids = UserContact.where("number = ?", '1234').pluck(:app_id).uniq
users = User.where(:id => user_ids)
THIRD: in ruby instead of doing this:
arr=[]
contact.each do|c|
arr << c.app_id
end
do this:
arr = contact.inject([]) {|arr, c| arr << c.app_id}
FOURTH: As in all my examples your syntax is mostly Rails 2. I assume you are using rails 2? If so you might need to upgrade.
FIFTH: use plural variable names if you return more than one object. Hence
contact = UserContact.....
name=User.....
should be
contacts = UserContact.find.....
users = User.find.....
LAST:
User.joins(:user_contacts).where("user_contacts.number = ?", '1234')
might be good