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Relationships
( v1 )
- # One to One
- # Implementation
- # One To Many
- # Implementation
- # Many to Many
- # Implementation
- # Saving Many to Many Relationships
- # Saving Data To Pivot Table
- # Taxonomy Relationships
Model relationships define how records are related in the database. The main relationship types include: "one to one", "one to many", and "many to many".
One to One
In a one to one relationship, one record can have only one reference to another record and vice-versa. For example, one Seat
can have one Person
if you are booking a plane flight.
Implementation
Take the plane flight example where one Person
and have one Seat
. For the Person
model, let's assume there is a table named wp_people
with the columns id
, name
, and email
. For the Seat
model lets assume there is a table named wp_seats
with the columns id
, person_id
, seat_number
, and price
. How would you represent the database relationship in your TypeRocket models?
Take a look at the Person
model.
<?php
namespace App\Models;
use \TypeRocket\Models\Model;
class Person extends Model
{
protected $resource = 'people';
/**
* Get the seat record associated with the person.
*/
public function seat()
{
return $this->hasOne('\App\Models\Seat', 'person_id');
}
}
And, look at the Seat
model.
<?php
namespace App\Models;
use \TypeRocket\Models\Model;
class Seat extends Model
{
protected $resource = 'seats';
/**
* Get the person record associated with the seat.
*/
public function person()
{
return $this->belongsTo('\App\Models\Person', 'person_id');
}
}
Now, you can access the Seat
from the Person
using the seat()
method. Take a look at the example where $person
is an instance of Person
.
$seat = $person->findById(1)->seat()->get();
You can also access the Person
in a Seat
. Take a look at the example where $seat
is an instance of Seat
.
$seat = $seat->findById(1)->person()->get();
One To Many
In one to many relationships, one record can have many other related records. For example, one Game
can have many a Player
in a video game.
Implementation
Take the video game example where one Game
and have many a Player
. For the Game
model, let's assume there is a table named wp_games
with the columns id
and name
. For the Player
model, let's assume there is a table named wp_players
with the columns id
, games_id
and name
. How would you represent the database relationship in your TypeRocket models?
Take a look at the Game
model.
<?php
namespace App\Models;
use \TypeRocket\Models\Model;
class Game extends Model
{
protected $resource = 'games';
/**
* Get the player records associated with the game.
*/
public function players()
{
return $this->hasMany('\App\Models\Player', 'games_id');
}
}
And, look at the Player
model.
<?php
namespace App\Models;
use \TypeRocket\Models\Model;
class Player extends Model
{
protected $resource = 'players';
/**
* Get the game record associated with the player.
*/
public function game()
{
return $this->belongsTo('\App\Models\Game', 'games_id');
}
}
Now, you can access the Player
records from the Game
using the players()
method. Take a look at the example where $game
is an instance of Game
.
$players = $game->findById(1)->players()->get();
You can also access the Game
from a Player
. Take a look at the example where $player
is an instance of Player
.
$game = $player->findById(1)->game()->get();
Many to Many
In many to many relationships, many records can have many other related records. For example, many an Author
can have many a Book
and vice-versa in a bookstore.
Implementation
Many to many relationships are a more complicated topic. For brevity, just remember that many to many relationships require a "junction table". A junction table stores the relationship associations as records.
Take the bookstore example. For the junction table lets assume it is named wp_authors_books
with the columns authors_id
and books_id
. For the Author
model, let's assume there is a table named wp_authors
with the columns id
and name
. For the Book
model, let's assume there is a table named wp_books
with the columns id
, title
, price
and pages
. How would you represent the database relationship in your TypeRocket models?
Take a look at the Author
model.
<?php
namespace App\Models;
use \TypeRocket\Models\Model;
class Author extends Model
{
protected $resource = 'authors';
/**
* Get the player records associated with the game.
*/
public function books()
{
$model = '\App\Models\Book';
$table = 'wp_authors_books';
return $this->belongsToMany($model, $table, 'books_id', 'authors_id');
}
}
And, look at the Book
model.
<?php
namespace App\Models;
use \TypeRocket\Models\Model;
class Book extends Model
{
protected $resource = 'books';
/**
* Get the player records associated with the game.
*/
public function authors()
{
$model = '\App\Models\Author';
$table = 'wp_authors_books';
return $this->belongsToMany($model, $table, 'authors_id', 'books_id');
}
}
Now, you can access the Book
records of the Author
using the books()
method. Take a look at the example where $author
is an instance of Author
.
$authors_books = $author->findById(1)->books()->get();
Now, you can access the Author
records of the Book
using the authors()
method. Take a look at the example where $book
is an instance of Book
.
$books_authors = $book->findById(1)->authors()->get();
Saving Many to Many Relationships
To save the relationship of a Book
to an Author
use the attach()
method. For example, if you have author records with the IDs 1
, 2
, and 3
you can attach them to a book as follows.
$book->findById(1)->authors()->attach([1,2,3]);
You can also detach author records with the detach()
method.
$book->findById(1)->authors()->detach([4,5,6]);
If you want to have only a specific set or records applied then you would need to detach all records and then attach the records you want.
$books_authors = $book->findById(1)->authors();
$books_authors->detach();
$books_authors->attach([1,2,3]);
Or, you can use the shortcut method sync()
to detach all authors and then attach the desired authors.
$book->findById(1)->authors()->sync([1,2,3]);
Saving Data To Pivot Table
To attach extra data to a pivot table row, pass an array
to the attach method.
$date = date('Y-m-d H:i:s');
$books_authors = $book->findById(1)->authors();
// attach author to book with pivot table data
$books_authors->attach([
[1, 'units' => '12', 'created_at' => $date],
[2, 'units' => '4', 'created_at' => $date],
[3, 'units' => '2', 'created_at' => $date],
]);
Taxonomy Relationships
If you have a custom post type model with custom taxonomies, you can define the relationship using the belongsToTaxonomy()
method.
<?php
namespace App\Models;
use TypeRocket\Models\WPPost;
class Post extends WPPost
{
protected $postType = 'post';
public function categories()
{
return $this->belongsToTaxonomy(Category::class, 'category');
}
public function tags()
{
return $this->belongsToTaxonomy(Tag::class, 'post_tag');
}
}
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