Laravel 4 Eloquent get ids of relations - php

Question

I'm building a client application that needs to have the ids of related models in my server API response.
In my example I've got two models, a Post and a Tag model. The relationship between them is many-to-many, so a pivot table is required.
class Post extends Eloquent {
protected $fillable = [ 'title', 'body' ];
public function tags()
{
return $this->hasMany('Tag');
}
}
class Tag extends Eloquent {
protected $fillable = [ 'title' ];
public function posts()
{
return $this->belongsToMany('Post');
}
}
I've got a resourcefull controller set up on the /api/posts route like this:
class PostsController extends \BaseController {
public function index()
{
$posts = Post::all();
return Response::json([ 'posts' => $posts->toArray() ]);
}
}
This will return a response much like this one:
{
"posts": [
{
"title": "Laravel is awesome",
"body": "Lorem Ipsum..."
},
{
"title": "Did I mention how awesome Laravel is?",
"body": "Lorem Ipsum..."
}
]
}
What I'm looking for is an easy way to include the ids of the related Tags model in the response like this:
{
"posts": [
{
"title": "Laravel is awesome",
"body": "Lorem Ipsum...",
"tags": [ 1, 2, 3 ]
},
{
"title": "Did I mention how awesome Laravel is?",
"body": "Lorem Ipsum...",
"tags": [ 1, 2, 4 ]
}
]
}

Answer 1

This isn't the most elegant solution, but it may work like you want (code not tested)
public function index()
{
$posts = Post::all();
$postsArray = array();
foreach ($posts as $post)
{
$postArray = $post->toArray();
$postArray['tags'] = array_values($post->tags->lists('id'));
$postsArray[] = $postArray;
}
return Response::json([ 'posts' => $postsArray]);
}

Answer 2

Add the following code to your Model/BaseModel:
/**
* Set additional attributes as hidden on the current Model
*
* #return instanceof Model
*/
public function addHidden($attribute)
{
$hidden = $this->getHidden();
array_push($hidden, $attribute);
$this->setHidden($hidden);
// Make method chainable
return $this;
}
/**
* Convert appended collections into a list of attributes
*
* #param object $data Model OR Collection
* #param string|array $levels Levels to iterate over
* #param string $attribute The attribute we want to get listified
* #param boolean $hideOrigin Hide the original relationship data from the result set
* #return Model
*/
public function listAttributes($data, $levels, $attribute = 'id', $hideOrigin = true)
{
// Set some defaults on first call of this function (because this function is recursive)
if (! is_array($levels))
$levels = explode('.', $levels);
if ($data instanceof Illuminate\Database\Eloquent\Collection) // Collection of Model objects
{
// We are dealing with an array here, so iterate over its contents and use recursion to look deeper:
foreach ($data as $row)
{
$this->listAttributes($row, $levels, $attribute, $hideOrigin);
}
}
else
{
// Fetch the name of the current level we are looking at
$curLevel = array_shift($levels);
if (is_object($data->{$curLevel}))
{
if (! empty($levels))
{
// We are traversing the right section, but are not at the level of the list yet... Let's use recursion to look deeper:
$this->listAttributes($data->{$curLevel}, $levels, $attribute, $hideOrigin);
}
else
{
// Hide the appended collection itself from the result set, if the user didn't request it
if ($hideOrigin)
$data->addHidden($curLevel);
// Convert Collection to Eloquent lists()
if (is_array($attribute)) // Use specific attributes as key and value
$data->{$curLevel . '_' . $attribute[0]} = $data->{$curLevel}->lists($attribute[0], $attribute[1]);
else // Use specific attribute as value (= numeric keys)
$data->{$curLevel . '_' . $attribute} = $data->{$curLevel}->lists($attribute);
}
}
}
return $data;
}
You can use it on your Model/Collection Object like this:
// Fetch posts data
$data = Post::with('tags')->get(); // or use ->first()
// Convert relationship data to list of id's
$data->listAttributes($data, 'tags');
$data will now contain the following object store:
{
"posts": [
{
"title": "Laravel is awesome",
"body": "Lorem Ipsum...",
"tags_id": [ 1, 2, 3 ]
},
{
"title": "Did I mention how awesome Laravel is?",
"body": "Lorem Ipsum...",
"tags_id": [ 1, 2, 4 ]
}
]
}
It also supports nested relationships:
// Fetch posts data
$data = Post::with('comments', 'comments.tags')->get(); // or use ->first()
// Convert relationship data to list of id's
$data->listAttributes($data, 'comments.tags');

Answer 3

Eloquent relationship returns a collection object which you can filter or even modify, say if you need only an array of the id's you can do this:
$posts->pluck('id');
$posts->pluck('id')->toArray();

Answer 4

I think you need to use the $appends property. Take a look at the docs here http://laravel.com/docs/eloquent#converting-to-arrays-or-json.
This question also is relevant as he encountered the same issue as you (see the edit on the accepted answer).
Add a custom attribute to a Laravel / Eloquent model on load?