Joining Three tables in Rails3

Question

I am using http://guides.rubyonrails.org/ to learn ruby & rails. I have problem with joining three tables. , so I made new project as this example: http://guides.rubyonrails.org/association_basics.html#the-has_many_through-association i have three tables physicians, appointments & patients

Models:

physician.rb

class Physician < ActiveRecord::Base
    has_many :appointments
    has_many :patients, :through => :appointments
  attr_accessible :name
end

appointment.rb

class Appointment < ActiveRecord::Base
    belongs_to :physician
    belongs_to :patient
  attr_accessible :appointment_date, :patient_id, :physician_id
end

patient.rb

class Patient < ActiveRecord::Base
    has_many :appointments
    has_many :physicians, :through => :appointments
  attr_accessible :name
end

I want to display the patient name, physician name & appointment_date. how to do this. thanks in advance.

Answer 1

I believe, although I am not sure, that you are looking for the way to access objects and their associations in views. Is that correct?

I will give you an example using the Appointment model.

AppointmentsController

class AppointmentsController < ApplicationController
  def index
    @appointments = Appointment.includes(:physician, :patient).order(:appointment_date)
  end
end

appointments#index (Haml syntax)

%ul
  - @appointments.each do |appointment|
    %li
      = appointment.appointment_date
      %br
      %strong Physician:
      = link_to appointment.physician.name, appointment.physician
      %br
      %strong Patient:
      = link_to appointment.patient.name, appointment.patient

This would give you a list of appointments with their dates, physicians, and patients.

Is this the sort of help for which you were looking?

Answer 2

In Appointment Controller:

def index
   @appointments = Appointment.order("appointment_date DESC")
end

In Appointments#index

<% for appointment in @appointments %>

          <%= link_to appointment.patient.name, patients_path(appointment.patient) %>
          &nbsp;
          Appointment for
          &nbsp;
          <%= link_to appointment.physician.name, physician_path(appointment.physician) %>
          <% if appointment.appointment_date? %>

              <%= appointment.appointment_date %>
          <% end %>
  <% end %>