API Resource: Using count() with whenLoaded()

I would look at using the withCount method. It's a trivial db query to get the count this way.

https://laravel.com/docs/7.x/eloquent-relationships#counting-related-models

@jbloomstrom withCount() doesn't load the relationship though, just a count.

"If you want to count the number of results from a relationship without actually loading them you may use the withCount method..."

Give this a go

'playedUpCount'=> $this->whenLoaded('playedUps', function() {
    return $this->playedUps->count()
}),

@sinnbeck that's the one, thanks!

Searching to do the same thing: get the count only if it exists.

And Actually the way @sinnbeck says and marked as the answer does the exact same thing that @jbloomstrom and has been judged as "unappropriate":

'playedUpCount'=> $this->whenLoaded('playedUps', function() { // If the playedUps relation has ben loaded from the controller
    return $this->playedUps->count() // Then it count the collection's items
}),

That's definitively not a COUNT() from the database and does the exact same thing that @jbloomstrom has said: it loads the entire relation's collection, and then does just a count on the collection's elements

To do the same, I have done like this:

class ShopResource extends \Illuminate\Http\Resources\Json\Resource
{
    public function toArray($request)
    {
        $resource = [
            'id' => $this->id,
            'name' => $this->name,
            'description' => $this->description,
            'lat' => $this->price,
            'lng' => $this->quantity,
            'photos' => $this->whenLoaded('photos'),
            'products' => ProductResource::collection($this->whenLoaded('products'))
        ];

        if ($this->products_count) {
            $resource['products_count'] = $this->products_count;
        }

        return $resource;
    }
}

And then from the controller:

// Get the count directly from the relationship query
$shops = Shop::withCount('products');
return new JsonResponse(
    ShopResource::collection($shops->get())
);

@romainb I agree :) It does make more sense to do both in database instead of php. A quick benchmark would most likely show that your version is faster when working with many records. You might want to actually load the products in you example as well, to make it complete

$shops = Shop::withCount('products')->with('products');
return new JsonResponse(
    ShopResource::collection($shops->get())
);

When using withCount() or loadCount(), Laravel will automatically add FIELDNAME_count as a primary attribute, NOT as a relation. So you can just do this:

$teams = Team::withCount('playedUps')->otherQueryCommands()->get();
return TeamResource::collection($teams);

And in your resource you only need this:

public function toArray($request)
{
    return parent::toArray($request); // All primary attributes
}

playedUps_count will be automatically added/removed based on withCount('playedUps')

If you need to add more conditional relations to the resource:

public function toArray($request)
{
    return array_merge(
        parent::toArray($request), // All primary attributes
        [
            'playedUps' => $this->whenLoaded('playedUps'),
            'otherRelation' => $this->whenLoaded('otherRelation'),
        ]
    );
}

Old posts though but I will add this: you can instead add the count attributte to the model:

class Players extends Eloquent
{
    protected $withCount = [
        'playedups',
    ];
}

then in your resource

public function toArray($request)
    {
        return [

            'id' => $this->id,
            'name' =>  $this->name,         
            'projects_count' => $this->playedups_count

        ];
       
    }