Setting up a Rails has_many :through relationship with meaningful relationship table #rails #activerecord #relations

gistfile1.md

##References

• ActiveRecord Associations

##Create Models

Create tables:

rails g model Location

rails g model User

rails g model Checkin

Run migration:

rake db:migrate

Create migration:

rails g migration AddFieldsToTables

##Create Fields

Add to migration file:

class AddFieldsToTables < ActiveRecord::Migration
  def change
    add_column :user, :name, :string
    add_column :location, :name, :string
    add_column :checkin, :user_id, :integer
    add_column :checkin, :location_id, :integer
    add_column :checkin, :source_id: integer
  end
end

Run migration:

rake db:migrate

##Create Relationships

Add to models/location.rb

class Location < ActiveRecord::Base
  has_many :checkins
  has_many :users, :through => :checkins, :uniq => true #if you need unique records
end

Add to models/user.rb

class User < ActiveRecord::Base
  has_many :checkins
  has_many :locations, :through => :checkins, :uniq => true 
end

Add to models/checkins.rb

class Checkin < ActiveRecord::Base
  belongs_to :location
  belongs_to :user
end

##CRUD on has_many :through

Create new relationship

source_id = 1
@user = User.first
@location = Location.first
checkin = Checkin.new user: @user, lap: @lap, source_id: source_id

Count on association

@checkin_count = @user.locations.count

Thank you very much!