qunli02/ruby-objects-has-many-through-lab-nyc-web-career-042219

Ruby Object Relations: Has-Many-Through Lab

Objectives

1. Write classes that are related to each other via the "has-many-through" relationship.
2. Write methods that use the "has-many-through" relationship to deliver information on related objects.

Overview

In this lab, we'll be dealing with two sets of three classes.

We have a Song, Artist and Genre class. Songs belong to an artist and belong to a genre. A genre has many songs and an artist has many songs. An artist has many genres through its songs and a genre has many artists through its songs.

We also have an Appointment, Doctor and Patient class. Appointments belong to a Patient and a Doctor. A Doctor has many Appointments and a Patient has many Appointments. A Doctor has many Patients through its Appointments and a Patient has many Doctors through its Appointments.

Instructions

Start with the Artist/Song/Genre domain.

The Artist model:

The Song model:

The Genre model:

Now let's move on to our Doctor/Appointment/Patient domain model.

The Doctor model:

• The Doctor class needs an instance method, #new_appointment, that takes in a an instance of the Patient class and a date, and creates a new Appointment. That Appointment should know that it belongs to the doctor
• The Doctor class needs an instance method, #appointments, that iterates through all Appointments and finds those belonging to this doctor.
• The Doctor class needs an instance method, #patients, that iterates over that doctor's Appointments and collects the patient that belongs to each Appointments.

The Appointment model:

The Patient model:

• The Patient class needs an instance method, #new_appointment, that takes in an argument of a doctor and a date and creates a new Appointment. The Appointment should know that it belongs to the patient.
• The Patient class needs an instance method, #appointments, that iterates through the Appointments array and returns Appointments that belong to the patient.
• The Patient class needs an instance method, #doctors, that iterates over that patient's Appointments and collects the doctor that belongs to each Appointment.

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