Laravel relationship between three tables - php

Question

I have 3 tables:
Events
Ages
Books
Which I was relating them in the following way:
ages
id
name
books
id
title
age_book
id
age_id
book_id
events
id
name
event_age
id
event_id
age_id
event_age_book
event_age_id
book_id
Basically, a book can have many ages, an age can have many books, an event can have many ages, an event age can have many books.
My Event Model looks like this and works fine to get all event ages
class Event extends Model
{
public function ages()
{
return $this->belongsToMany(Age::class, 'event_age');
}
}
Age Model:
class Age extends Model
{
public function books(): BelongsToMany
{
return $this
->belongsToMany(Book::class)
->withTimestamps();
}
}
Book Model
class Book extends Model
{
public function ages(): BelongsToMany
{
return $this
->belongsToMany(Age::class, 'book_age', 'book_id','age_id')
->withTimestamps();
}
}
Im having trouble figuring out how to get all edition age books, is it possible to do it on the Event model?

Answer 1

Let's Review The Relationships
Seems you should only need 3 models, and 5 tables.
Books Belong to Ages
Events Belong to Ages
Ages Belongs to Books
Ages Belongs to Events
Your other models are alright, but your age model is missing a relationship to Event:
class Age extends Model
{
public function books(): BelongsToMany
{
return $this->belongsToMany(Book::class)
->withTimestamps();
}
public function events(): BelongsToMany
{
return $this->belongsToMany(Events::class,'event_age')
->withTimestamps();
}
}
That would allow:
$books->ages;
$events->ages;
$ages->book;
$ages->events;
And chaining...
$books = collect();
foreach($event->ages as $age){
$books->merge($ages->books);
}
$books->unique();
Books and Events
So, I gon't think you want age_event_books. I think what you really want is:
Events belong to Books
Books belong to Events
such that
book_events
- id
- book_id
- event_id
- age_id
And you'd have in book:
public function events()
{
return $this->BelongsToMany('App\Event')
->withTimestamps()
->withPivot('age_id');
}
And in event:
public function books()
{
return $this->belongsToMany('App\Book')->withTimestamps()
->withPiviot('age_id')->groupBy('age_id');
}
Giving you:
$event->books
$book->events
On the Front End
[O]n the frontend i'll need to get the most recent event and group books by age and books can belong to more than one age
$event = Event::latest();
$books = $event->books();
Then on the blade
#foreach($books as $age_id => $books)
<h4>{{Age::find($age_id)->name}}</h4>
#foreach($books as $book)
<div>$book->name</div>
#endforeach
#endforeach
Helpful Tip
You are supplying the relation table, which you have to do because you didn't follow the naming convention for joining tables. The convention is that the classes being joined should be listed alphabetically. So age_event instead of event_age.