How to make Laravel Resources work with polymorphic relation

Question

I have a polymorphic relation in a Laravel application. I want a user of the website to be able to give a rating to both a User model as well as Product model.

I have following models and relations

class Rating extends Model
{
    public function ratable()
    {
        return $this->morphTo();
    }
}

class User extends Authenticatable
{
    public function ratings()
    {
        return $this->morphMany('App\Rating', 'ratable');
    }
}

class Product extends Model
{ 
    public function ratings()
    {
        return $this->morphMany('App\Rating', 'ratable');
    }
 }

and the following database migration:

class CreateRatingsTable extends Migration
{
    public function up()
    {
        Schema::create('ratings', function (Blueprint $table) {
            $table->bigIncrements('id');
            $table->integer('ratable_id');
            $table->string('ratable_type');
            $table->double('rating');
            $table->text('comment');
            $table->timestamps();
        });
    }
}

I have defined two routes:

 1) Route::post('products/{product}/rating', 'ProductController@setRating')->name('products.rating');
 2) Route::post('users/{user}/rating', 'UserController@setRating')->name('users.rating');

I have the following code in the controller (will only show the Product example)

public function setRating(Request $request, Product $product)
    {
       $rating = new Rating();
       $rating->rating     =   $request->rating;
       $rating->comment    =   $request->comment;

       $product->ratings()->save($rating);
    }

The above works perfectly and the correct records get inserted in the database depending on whether the Product route or the User route is called.

Now, all the rest of my code is using Laravel Resources, and for consistency reasons, I have also defined a resource for Rating:

class RatingResource extends JsonResource
{
    public function toArray($request)
    {
        return [
            'ratable_id'    =>      $this->ratable_id,
            'ratable_type'  =>      $this->ratable_type,
            'rating'        =>      $this->rating,
            'comment'       =>      $this->comment

        ];
    }
}

I'm also changing the ProductController code to use this resource

public function setRating(Request $request, Product $product)
{
    return new RatingResource(Rating::create([
       'ratable_id'    =>      $product->id,
       'ratable_type'  =>      $product,
       'rating'        =>      $request->rating,
       'comment'       =>      $request->comment,
    ]));
}

In postman, I'm calling the REST API:

http://{{url}}/api/products/1/rating with body: 
    rating: 4
    comment: "Test"

Yet, I always get following error message

"SQLSTATE[HY000]: General error: 1364 Field 'ratable_id' doesn't have a default value (SQL: insert into ratings (rating, comment, updated_at, created_at) values (4, test, 2019-09-07 13:44:22, 2019-09-07 13:44:22))"

I'm not passing the ratable_id and ratable_typeas I'm filling these in already in the controller code.

I somehow need to pass the resource that it's a Productor a UserI'm giving a rating for.

How can I make this work?

Answer 1

The problem probably is that ratable_id is missing from $fillable.

Try $product->ratings()->create([...data...]) so you don't have to set ratable_id and ratable_type yourself:

public function setRating(Request $request, Product $product)
{
    return new RatingResource(
         $product->ratings()->create([
             'rating'  => $request->rating,
             'comment' => $request->comment,
         ])
    );
}