CODEWITHSUNDEEP
mysqlrubyruby-on-rails-4
Vibhoo Mishra
Vibhoo Mishra

Reputation: 142

how do I check whether user exists in db or not

In my rails application, I have relationship setup such has user has_many :contacts, all the contacts of a user are stored in contacts

when I do user.contacts i get all the contacts of a current_user I wanted to check how many of the user contacts are already registered meaning already existing in users table. I have some solution in mind my comparing of each contact of a user with the db(users table). But the process will very time consuming looking for a more optimized way.

Upvotes: 0

Views: 86

Answers (2)

aBadAssCowboy
aBadAssCowboy

Reputation: 2520

Assuming your Contact model has email as an attribute and User also has email as an attribute. To find the number of users that are registered with the emails that are as contacts of current_user, you would do:

contact_emails = current_user.contacts.pluck("contacts.email")
no_of_users_registered = User.where(email: contact_emails).count

Upvotes: 1

Jacob Brown
Jacob Brown

Reputation: 7561

You could use an association extension to do this:

class User 
  has_many :contacts do
    def persisted
      where(email: User.select(:email))
    end
  end
end

Assuming both your contact and user models have an email field.

Upvotes: 0

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