Set default value for relation in Laravel model based on another relation's value

Question

I am querying for a Food record and its relationships the following way, setting a default value for one of the relation:

$this->foodModel->with(['mainImage', 'category'])->find($foodId);

App\Models\Food

public function category()
{
    return $this->belongsTo('App\Models\FoodCategory', 'food_categ_id');
}

public function mainImage() 
{
    $placeholderUrl = asset('images/placeholders/food.jpg');
    
    return $this->morphOne('App\Models\Media', 'parentable')
        ->where('primary', 1)
        ->withDefault([
            'url' => $placeholderUrl
        ]);
}

But now I want to set the default value according to the Food's category relation for that specific record and I'm not sure how to access the data.

public function mainImage() 
{
    $placeholderUrl = asset('images/placeholders/food-categories/' . $category->name . '.jpg') // IS IT POSSIBLE?

    return $this->morphOne('App\Models\Media', 'parentable')
        ->where('primary', 1)
        ->withDefault([
            'url' => $placeholderUrl
        ]);
}

Answer 1

What about to add mainImage into FoodCategory model too and to set default image for each categories?

App\Models\FoodCategory

public function mainImage() 
{
    return $this->morphOne('App\Models\Media', 'parentable')->where('primary', 1)->withDefault(function (Media $media, FoodCategory $category) {
        $media->url = asset('images/placeholders/food-categories/' . $category->name . '.jpg');
    });
}

and then into Food model to have Attribute image like this:

App\Models\Food

/**
 * The accessors to append to the model's array form.
 *
 * @var array
 */
protected $appends = ['image'];

public function image(): Attribute
{
    return Attribute::make(
        get: fn () => $this->mainImage ?? $this->category->mainImage
    );
}

public function mainImage()
{
    return $this->morphOne('App\Models\Media', 'parentable')->where('primary', 1);
}

and you need to add category.mainImage for lazy loading too

$this->foodModel->with(['mainImage', 'category', 'category.mainImage'])->find($foodId);

If the food has mainImage the image and mainImage will be the same:

But if the foot does not have mainImage, image will contain the mainImage from the category

{
  "id": 3,
  "name": "Dr. Reba Dicki",
  "food_categ_id": 1,
  "image": {
    "id": 16,
    "parentable_id": "3",
    "parentable_type": "App\\Models\\Food",
    "primary": 1,
    "url": "https://www.kirlin.com/et-consectetur-aliquam-deserunt-fugit-aut-vel-voluptate"
  },
  "main_image": {
    "id": 16,
    "parentable_id": "3",
    "parentable_type": "App\\Models\\Food",
    "primary": 1,
    "url": "https://www.kirlin.com/et-consectetur-aliquam-deserunt-fugit-aut-vel-voluptate"
  },
  "category": {
    "id": 1,
    "name": "Christophe Hansen"
  }
}

... without primary Food media

{
  "id": 5,
  "name": "Julie Smitham",
  "food_categ_id": 5,
  "image": {
    "id": 5,
    "parentable_id": "5",
    "parentable_type": "App\\Models\\FoodCategory",
    "primary": 1,
    "url": "http://www.padberg.info/et-ab-numquam-harum-ut-aut-doloribus.html"
  },
  "main_image": null,
  "category": {
    "id": 5,
    "name": "Columbus Krajcik",
    "main_image": {
      "id": 5,
      "parentable_id": "5",
      "parentable_type": "App\\Models\\FoodCategory",
      "primary": 1,
      "url": "http://www.padberg.info/et-ab-numquam-harum-ut-aut-doloribus.html"
    }
  }
}

UPDATE

There is a way withDefault but I'm not prefer this because will make a db query for each:

Update only Food model and mainImage to be:

public function mainImage()
{
    return $this->morphOne('App\Models\Media', 'parentable')
        ->where('primary', 1)
        ->withDefault(function (Media $media, Food $food) {
            $meda = $media->where([
                'parentable_type' => FoodCategory::class,
                'parentable_id' => $food->food_categ_id,
                'primary' => true,
            ])->first();

            if (!$meda) {
                $meda = new Media();
                $meda->url = asset('images/placeholders/food.jpg');
            }

            return $meda;
        });
}

with Food media

{
  "id": 3,
  "name": "Dr. Reba Dicki",
  "food_categ_id": 1,
  "main_image": {
    "id": 16,
    "parentable_id": "3",
    "parentable_type": "App\\Models\\Food",
    "primary": 1,
    "url": "https://www.kirlin.com/et-consectetur-aliquam-deserunt-fugit-aut-vel-voluptate"
  },
  "category": {
    "id": 1,
    "name": "Christophe Hansen"
  }
}

without Food media, but with FoodCategory media

{
  "id": 5,
  "name": "Julie Smitham",
  "food_categ_id": 5,
  "main_image": {
    "id": 5,
    "parentable_id": "5",
    "parentable_type": "App\\Models\\FoodCategory",
    "primary": 1,
    "url": "http://www.padberg.info/et-ab-numquam-harum-ut-aut-doloribus.html"
  },
  "category": {
    "id": 5,
    "name": "Columbus Krajcik"
  }
}

without Food and FoodCategory media

{
  "id": 4,
  "name": "Clovis Koepp",
  "food_categ_id": 4,
  "main_image": {
    "url": "http://localhost/images/placeholders/food.jpg"
  },
  "category": {
    "id": 4,
    "name": "Bernita Kuhn"
  }
}

UPDATE 2

For Laravel < 9, you need to use eloquent mutators

App\Models\Food

public function getImageAttribute()
{
    return $this->mainImage ?? $this->category->mainImage;
}