join two tables to get data rails 4

class Guardian < ActiveRecord::Base
  has_many :patients
  has_one :user, as: :profile
  accepts_nested_attributes_for :user
end


class User < ActiveRecord::Base
  belongs_to :profile, :polymorphic => true

  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable
end

User migration

class DeviseCreateUsers < ActiveRecord::Migration
  def change
    create_table(:users) do |t|
      ## Database authenticatable
      t.string :email,              :null => false, :default => ""
      t.string :encrypted_password, :null => false, :default => ""
      t.string :username, :null => false
      t.string :address
      t.integer :age
      t.string :gender
      t.string :name
      t.integer :profile_id
      t.string :profile_type

      ## Recoverable
      t.string   :reset_password_token
      t.datetime :reset_password_sent_at

      ## Rememberable
      t.datetime :remember_created_at

      ## Trackable
      t.integer  :sign_in_count, :default => 0, :null => false
      t.datetime :current_sign_in_at
      t.datetime :last_sign_in_at
      t.string   :current_sign_in_ip
      t.string   :last_sign_in_ip


      t.timestamps
    end

    add_index :users, :email,                :unique => true
    add_index :users, :reset_password_token, :unique => true
  end
end

class DeviseCreateUsers < ActiveRecord::Migration
  def change
    create_table(:users) do |t|
      ## Database authenticatable
      t.string :email,              :null => false, :default => ""
      t.string :encrypted_password, :null => false, :default => ""
      t.string :username, :null => false
      t.string :address
      t.integer :age
      t.string :gender
      t.string :name
      t.integer :profile_id
      t.string :profile_type

      ## Recoverable
      t.string   :reset_password_token
      t.datetime :reset_password_sent_at

      ## Rememberable
      t.datetime :remember_created_at

      ## Trackable
      t.integer  :sign_in_count, :default => 0, :null => false
      t.datetime :current_sign_in_at
      t.datetime :last_sign_in_at
      t.string   :current_sign_in_ip
      t.string   :last_sign_in_ip
      t.timestamps
    end

    add_index :users, :email,                :unique => true
    add_index :users, :reset_password_token, :unique => true
    end
end

Guardian migration

class CreateGuardians < ActiveRecord::Migration
  def change
    create_table :guardians do |t|
      t.string :family_name

      t.timestamps
    end
  end
end

I want to get data from user table and guardian table in a single variable guardian has one user and user belongs_to guardian as profile(polymorphic). i want to get data from user table and from guardian table where guardian_id=users.profile_id

回答1:

Try

Guardian.select("*").joins(:user)

Edit:

if you have columns with the same name from the join you can do

Guardian.select("guardians.family_name, guardians.id as g_id, users.id as u_id,
    users.name, users.email, users.username, users.address, users.age,
    users.gender").joins(:user).where(:users => {:u_id => @user_session.id})

回答2:

For some reason above answer didn't work for me, so I tried direct sql query

sqlQuery = "select tableA.column1, tableB.column2 from tableA inner join tableB on tableA.some_id = tableB.id"
ActiveRecord::Base.connection.execute(sqlQuery)