Laravel create a 1-1 relationship from a many-many relationship - php

Question

Hi I'm having a struggle trying to return a single record from a many to many relationship.
So in my app I've Clubs and Addresses entities.
Clubs have 0, 1 or n Addresses and one of them may be the main address.
An Address can also be used by some other entities (like Events, Members etc..)
My tables are the following :
clubs: id, name
addresses: id, street, city, zip club
club_address: id, club_id, address_id, is_main
I can currently request all the addresses of my club like so :
class Club {
public function addresses()
{
return $this->belongsToMany('Address', 'club_address', 'club_id', 'address_id')->withPivot('is_main'); // club_address
}
}
Now what I'd like is to get the main address or null when I request a club.
I can't be satisfied with simply adding ->wherePivot('is_main', '=', 1) because it's still returning an array of 1 or 0 element when I want an array or null.
I'd like something like this
class Club {
// Get all the addresses in an array
public function addresses()
{
return $this->belongsToMany('Address', 'club_address', 'club_id', 'address_id')->withPivot('is_main'); // club_address
}
// Get the main address or null
public function address()
{
return $this->addresses()->wherePivot('is_main', '=', 1)->first();
}
}
But the problem is that I can't eager load address because it's not returning a Relation Model ...

Answer 1

first() on an eloquent model returns a collection - even if that collection is zero (which is what you have basically said).
However first() on a collection returns null is there is no first...
So..
class Club {
public function addresses()
{
return $this->belongsToMany('Address', 'club_address', 'club_id', 'address_id')->withPivot('is_main');
}
public function address()
{
// First first is on the model, second first
// is on the collection
return $this->addresses()
->wherePivot('is_main', '=', 1)
->first()
->first();
}
}
Note This is essentially just a shorthand trick. Your attribute could just as easily, and possibly more readable, use something like:
class Club {
public function addresses()
{
return $this->belongsToMany('Address', 'club_address', 'club_id', 'address_id')->withPivot('is_main');
}
public function address()
{
$record = $this->addresses()
->wherePivot('is_main', '=', 1)
->first();
return count($record) === 0 ? null : $record;
}
}

Answer 2

I found a way to do the trick by extending the BelongsToMany Relation class and overriding two methods with their BelongsTo Relation equivalent.
But I wouldn't say it's prudent to use this, but it seems ok for my uses.
namespace App\Relations;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Builder;
use Illuminate\Database\Query\Expression;
use Illuminate\Database\Eloquent\Collection;
use Illuminate\Database\Eloquent\ModelNotFoundException;
use Illuminate\Database\Eloquent\Relations\BelongsToMany;
class BelongsToOneFromMany extends BelongsToMany {
/**
* Initialize the relation on a set of models.
*
* #param array $models
* #param string $relation
* #return array
*/
public function initRelation(array $models, $relation)
{
foreach ($models as $model)
{
$model->setRelation($relation, null);
}
return $models;
}
/**
* Match the eagerly loaded results to their parents.
*
* #param array $models
* #param \Illuminate\Database\Eloquent\Collection $results
* #param string $relation
* #return array
*/
public function match(array $models, Collection $results, $relation)
{
$foreign = $this->foreignKey;
$other = $this->otherKey;
// First we will get to build a dictionary of the child models by their primary
// key of the relationship, then we can easily match the children back onto
// the parents using that dictionary and the primary key of the children.
$dictionary = array();
foreach ($results as $result)
{
$dictionary[$result->getAttribute($other)] = $result;
}
// Once we have the dictionary constructed, we can loop through all the parents
// and match back onto their children using these keys of the dictionary and
// the primary key of the children to map them onto the correct instances.
foreach ($models as $model)
{
if (isset($dictionary[$model->$foreign]))
{
$model->setRelation($relation, $dictionary[$model->$foreign]);
}
}
return $models;
}
}