Laravel resources - how to check if given value exists?

Question

I'm using laravel resources to get data for api:

        return [
            'id' => $this->id,
            'unread' => $this->unread,
            'contact' => UserResource::collection($this->users),
        ];

And this is working fine. The problem is when 'users' is empty. I mean - not every time my controller is loading users from my relations:

    $offers = Offer::where('user_id', $user_id)->orderBy('created_at','desc')->get();
    foreach ($offers as $offer)
    {
        $offer->setRelation('users', $offer->users->unique());
    }
    return OfferShortResource::collection($offers);

sometimes - this relation does not exists. But not the relation is problem, because - my resource is not loading the relation - the relatin is loaded inside controller.

So how can I add some kind of logic to resources? - to tell basically - users property may not exists - then do not load data here, or even - do not check $this->users relation

edit: I tried to make it like this:

 use Illuminate\Support\Arr;
 ...

      'contact' => $this->when(Arr::exists($this, 'users'), function () {
                    return UserResource::collection($this->users);
                }),

but this is giving always false

edit 2: relation in the Offer model

 public function users(){
        return $this->belongsToMany(User::class, 'messages', 'offer_id', 'from')
       ->where('users.id', '!=', auth()->user()->id);

Laravel Docs - Eloquent - API Resources - Conditional Relationships whenLoaded — lagbox
– lagbox, Commented Jul 4, 2018 at 19:57
I tried this, giving error: "message": "Class 'App\\Post' not found", "exception": "Symfony\\Component\\Debug\\Exception\\FatalThrowableError", "file": "C:\\www2\\medpraca2\\vendor\\laravel\\framework\\src\\Illuminate\\Database\\Eloquent\\Concerns\\HasRelationships.php", — gileneusz
– gileneusz, Commented Jul 4, 2018 at 20:00
lol, no, my code is like: 'contact' => UserResource::collection($this->whenLoaded('users')), — gileneusz
– gileneusz, Commented Jul 4, 2018 at 20:02
then that error obviously has nothing to do with what you have shown here, so not sure what you want anyone to do for you — lagbox
– lagbox, Commented Jul 4, 2018 at 20:03
trust me, when I comment this line there is no error, and my relation is working well inside controller — gileneusz
– gileneusz, Commented Jul 4, 2018 at 20:05

Brian Lee · Accepted Answer · 2018-07-05 08:12:49Z

11

Try using whereHas:

Offer::whereHas('users', function ($query) use ($user_id) {
    $query->where('user_id', $user_id);
})->orderByDesc('created_at')->get();

The optional helper is useful for accessing properties that may not be defined:

optional($this->user)->name

The when method should work for you, try the following:

'contact' => $this->when(property_exists($this, 'users'), function () {
    return UserResource::collection($this->users);
}),

Also try:

isset($this->users)

edited Jul 5, 2018 at 8:12

answered Jul 4, 2018 at 20:14

Brian Lee

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7 Comments

gileneusz Over a year ago

It is a logic for controller, in controller everything works fine, I want to add logic to api Resource to conditionally add 'contact' value

gileneusz Over a year ago

checking again for today and property_exists($this, 'users') isn't working inside resources, gives me always false, even if I would put it other value like property_exists($this, 'unread') etc

Brian Lee Over a year ago

Can you include the full code for OfferShortResource?

gileneusz Over a year ago

no, but I've tried now isset($this->users) and it works with it, you may update the answer and I'll accept again

gileneusz Over a year ago

anyway it's strange that property_exists is not working inside api resources

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