Add the count field to Item model.

app/Models/Item.php

@@ -19,8 +19,21 @@ class Item extends Model
         'price',
         'image',
         'category_id',
+        // if an item in a cart, then the count is a nonzero value.
+        'count',
     ];
 
+    public function getCount()
+    {
+        return $this->count;
+    }
+
+    public function setCount($count = 1)
+    {
+        $this->count = $count;
+        $this->save();
+    }
+
     public function category(): BelongsTo
     {
         return $this->belongsTo(Category::class);

database/migrations/2023_06_14_140000_create_items_table.php

@@ -20,6 +20,7 @@ return new class extends Migration
             $table->string('description');
             $table->decimal('price', 8, 2);
             $table->string('image')->nullable();
+            $table->bigInteger('count')->default(0);
 
             $table->foreign('category_id')->references('id')
                  ->on('categories')->onDelete('cascade');