Laravel Many To Many Relationship getting data - php

Question

this is my campus model
i have stripped the models for readability
and of course there is join table named as campus_user with id, campus_id, user_id
users can subscribe to campuses
now i want 2 things
1. Get all the users subscribed to a specific campus
2. Check to see if a specific user ( say with id = 1 ) is subscribed to a specific campus ( say with id = 2 )
class Campus extends \Eloquent{
protected $table = "campuses";
public function users(){
return $this->belongsToMany("User");
}
}
// this is my user model
class User extends Eloquent implements UserInterface, RemindableInterface {
use UserTrait, RemindableTrait;
protected $table = 'users';
protected $hidden = array('password', 'remember_token');
public function campuses(){
return $this->belongsToMany('\Models\Campus');
}
}

Answer 1

Well the most "Eloquent like" way would be using relationship querying:
http://laravel.com/docs/4.2/eloquent#querying-relations
A simple example would be returning users with any campuses.
// Get users with any campus relationship.
$users = User::has('campuses')->get();
However you need something more powerful.
For 'users' in a specific 'campus'.
// Get 'users' in a 'campus' where the 'name' column equals 'foo'.
$campus = 'foo';
$users = User::whereHas('campuses', function($query) use ($campus) {
$query->where('name', $campus);
})->get();
For a specific 'user' in a specific 'campus' the code would almost be the same.
// Find the 'user' with a primary key of '1' in the 'campus' where
// the 'name' column equals 'foo'.
$primaryKey = 1;
$campus = 'foo';
$users = User::whereHas('campuses', function($query) use ($campus) {
$query->where('name', $campus);
})->find($primaryKey);
As you can see the last example replaced the get() method from the previous example.
You can do the same with the callback in the whereHas() method when you want to query using the primary key. This would result in the following.
...
$query->find($campus);
...
All the methods described above can be found in the Illuminate\Database\Eloquent\Builder class.
I would recommend taking a look at some of the source files to get a better understanding how request are handled.