Indexable trait

Using an index column for display purposes in your models is a common practice and can be quite effective for allowing custom ordering of items, such as products in an e-commerce application. However, if you want to make this functionality more reusable and maintainable, creating a trait with a polymorphic relationship is a good approach. Here's how you can implement it:

1. Create the Indexable Trait:

   This trait will handle the logic for ordering and reordering items.

   namespace App\Traits;
   
   use Illuminate\Database\Eloquent\Model;
   
   trait Indexable
   {
       public static function bootIndexable()
       {
           static::creating(function (Model $model) {
               if (is_null($model->index)) {
                   $model->index = $model->getMaxIndex() + 1;
               }
           });
       }
   
       public function scopeOrdered($query)
       {
           return $query->orderBy('index');
       }
   
       public function getMaxIndex()
       {
           return $this->newQuery()->max('index');
       }
   
       public function reorder($newIndex)
       {
           $this->index = $newIndex;
           $this->save();
       }
   }
   

2. Add the index Column to Your Models:

   Ensure that your models have an index column in their respective tables. You can add this column using a migration:

   use Illuminate\Database\Migrations\Migration;
   use Illuminate\Database\Schema\Blueprint;
   use Illuminate\Support\Facades\Schema;
   
   class AddIndexToYourModelTable extends Migration
   {
       public function up()
       {
           Schema::table('your_model_table', function (Blueprint $table) {
               $table->integer('index')->nullable();
           });
       }
   
       public function down()
       {
           Schema::table('your_model_table', function (Blueprint $table) {
               $table->dropColumn('index');
           });
       }
   }
   

3. Use the Trait in Your Models:

   Apply the Indexable trait to any model that requires custom ordering.

   namespace App\Models;
   
   use Illuminate\Database\Eloquent\Model;
   use App\Traits\Indexable;
   
   class Product extends Model
   {
       use Indexable;
   
       // Other model properties and methods
   }
   

4. Reordering Logic:

   You can now use the reorder method to change the order of items, and the ordered scope to retrieve items in the desired order.

   $product = Product::find(1);
   $product->reorder(5); // Change the index to 5
   
   $orderedProducts = Product::ordered()->get(); // Get products ordered by index
   

By using a trait, you encapsulate the logic related to indexing and make it reusable across different models. This approach also keeps your codebase clean and adheres to the DRY (Don't Repeat Yourself) principle.