Part 3: Testing Model Relationships in Laravel — POLYMORPHIC

Part 3: Testing Model Relationships in Laravel — POLYMORPHIC

This part deals with more complex model relationships, the polymorphic type. Just like before, we shall stick to the official documentation examples and work out befitting tests. To have a low down on the earlier parts see link directly below 👇

• Part 1: Intro and Schema Tests
• Part 2: Testing Basic Model Relationships
• Part 3: Testing Polymorphic Relationships ⏯

POLYMORPHIC RELATIONSHIPS

A polymorphic relationship allows a target model to belong to more than one type of model using a single association.  — Laravel.com

1. One-to-One Polymorphic Relationship

A one-to-one polymorphic relation is similar to a simple one-to-one relation; however, the target model can belong to more than one type of model on a single association.

Scenario:

A blog Post and a User may share a polymorphic relation to an Image model. Using a one-to-one polymorphic relation allows you to have a single list of unique images that are used for both blog post s and user accounts

morphTo()

— An image table can be morph ed in to any model (i.e serve many different models), eg User or Post model in our case.

// App/Image.php
...
public function imageable() 
{ 
 return $this->morphTo(); 
}

morphOne()

• — A user/post model can morph one instance of the same image model table (i.e make use of same image table but one record per user/post).
• — INVERSE of morphTo relationship.

// App/User.php
...
public function image() 
{ 
 return $this->morphOne(Image::class, 'imageable'); 
}

Files relevant to this test 👇

- **MODEL FILES(App/)
 -- User.php 
 -- Post.php
 -- Image.php

- **MIGRATION FILES(database/migrations/)
 -- 2014\10\12\000000\create\users\table.php
 -- 2019\09\27\100604\create\posts\table.php
 -- 2019\09\28\143143\create\images\table.php

- **MODEL FACTORY FILES(database/factories/)
 -- UserFactory.php 
 -- PostFactory.php
 -- ImageFactory.php

- **UNIT TEST FILES(tests/Units/)
 -- UserTest.php 
 -- PostsTest.php
 -- ImagesTest.php

2. One-to-Many (Polymorphic)

A “one-to-many polymorphic” relation is similar to a simple one-to-many relation; however, the target model can belong to more than one type of model on a single association. — Laravel.com

Scenario:

Users of your application can “comment” on both posts and videos. Using polymorphic relationships, you may use a single comments table for both of these scenarios.

morphTo()

— A comment table can be morph ed to any model (i.e serve many different models), eg Video or Post model in our case.

// App/Comment.php
...
public function commentable() 
{ 
 return $this->morphTo(); 
}

morphMany()

• — A video/post model can morph many instances of the same comment model table (i.e make use of same comment table for many records).
• — INVERSE of morphTo relationship.

// App/Video.php
...
public function comments() 
{ 
 return $this->morphMany(Comment::class, 'commentable'); 
}

Files relevant to this test 👇

**MODEL FILES(App/)

-- User.php 

-- Post.php

-- Video.php

-- Comment.php
**MIGRATION FILES(database/migrations/)

-- 2019\09\28\211240\create\videos\table.php

-- 2019\09\28\221627\add\commentable\id\and\commentable\type\to\comments\table.php
**MODEL FACTORY FILES(database/factories/)

-- VideoFactory.php
**UNIT TEST FILES(tests/Unit/)

-- PostsTest.php

-- VideosTest.php

-- CommentsTest.php

1. Many-to-Many (Polymorphic)

In progress…

Kindly check back soon

• 👉Part 1: Intro and Schema Tests
• 👉Part 2: Testing Basic Model Relationships
• ⏯Part 3: Testing Polymorphic Relationships