Creating meaningful user names in development

Question

I am trying to have my application automatically generate usernames to be used as a url. As a rule, they will add the user name and surname, however, when a user with the same name and surname already exists, he will add a number to the name, which increases for each.

This is the method I created:

def full_name first_name + ' ' + last_name end def user_name t_user_name = first_name.downcase.strip.gsub(' ', '').gsub(/[^\w-]/, '') + last_name.downcase.strip.gsub(' ', '').gsub(/[^\w-]/, '') user_name = t_user_name num = 1 while User.find_by_user_name(user_name).count > 0 num += 1 user_name = "#{t_user_name}#{num}" end end 

I am currently getting the error message:

 undefined method `find_by_user_name' 

What would I think would work automatically?

I also tried to give examples shown in this post:

create a unique username (omniauth + devise)

but I kept getting the error:

 Mysql2::Error: Unknown column 'users.login' in 'where clause': SELECT COUNT(*) FROM `users` WHERE `users`.`login` = 'bobweir' 

Although I added

 t.string :login, null: false, default: "" 

to users table

edit2: schema.rb

ActiveRecord :: Schema.define (version: 20150611033237) do

 create_table "users", force: :cascade do |t| t.string "first_name", limit: 255 t.string "last_name", limit: 255 t.string "email", limit: 255, default: "", null: false t.string "encrypted_password", limit: 255, default: "", null: false t.string "reset_password_token", limit: 255 t.datetime "reset_password_sent_at" t.datetime "remember_created_at" t.integer "sign_in_count", limit: 4, default: 0, null: false t.datetime "current_sign_in_at" t.datetime "last_sign_in_at" t.string "current_sign_in_ip", limit: 255 t.string "last_sign_in_ip", limit: 255 t.datetime "created_at", null: false t.datetime "updated_at", null: false end add_index "users", ["email"], name: "index_users_on_email", unique: true, using: :btree add_index "users", ["reset_password_token"], name: "index_users_on_reset_password_token", unique: true, using: :btree 

end

Answer 1

Rails takes the magic of find_by_sth by calling the attribute name in the method call, returning ActiveRecordRelation.

Since you do not have the user_name attribute in your model, Active Record will not be able to search on it (just imagine that it should be translated into an SQL query).

On the other hand, I would change my mind about the logic of your user_name method if I were you. Consider storing the username in your database.

By the way, in the second error that you mention, note that in the example that you have, it works with an input attribute that you simply don't have.