feat: rule for already in use sku for one retailer

app/Nova/Product.php

@@ -2,9 +2,13 @@
 
 namespace App\Nova;
 
+use App\Models\Retailer;
+use App\Rules\isSKUAvailable;
 use Illuminate\Http\Request;
 use Laravel\Nova\Fields\ID;
+use Laravel\Nova\Fields\Select;
 use Laravel\Nova\Fields\Text;
+use Laravel\Nova\Fields\Textarea;
 use Laravel\Nova\Http\Requests\NovaRequest;
 
 class Product extends Resource
@@ -32,6 +36,15 @@ class Product extends Resource
         'id',
     ];
 
+    public function getAllRetailers()
+    {
+        $list = array();
+        foreach (Retailer::get() as $retailer) {
+            $list[$retailer['id']] = $retailer['name'];
+        }
+        return $list;
+    }
+
     /**
      * Get the fields displayed by the resource.
      *
@@ -45,7 +58,25 @@ public function fields(NovaRequest $request)
 
             Text::make('Name')
                 ->sortable()
-                ->rules('required', 'max:255'),
+                ->rules('required', 'max:255', 'min:2'),
+
+            Select::make('Retailer', 'retailer_id')
+                ->options(
+                    $this->getAllRetailers()
+                )
+                ->rules('required'),
+
+            Text::make('SKU')
+                ->sortable()
+                ->rules('required', new isSKUAvailable($request->retailer_id)),
+
+            Text::make('Price')
+                ->sortable()
+                ->rules('required'),
+
+            Textarea::make('Description')
+                ->sortable()
+                ->rules('required'),
         ];
     }
 

app/Rules/isSKUAvailable.php

+<?php
+
+declare (strict_types = 1);
+
+namespace App\Rules;
+
+use App\Models\Product;
+use App\Models\Retailer;
+use Illuminate\Contracts\Validation\Rule;
+
+class isSKUAvailable implements Rule
+{
+
+    public ?int $retailer_id;
+    /**
+     * Create a new rule instance.
+     *
+     * @return void
+     */
+    public function __construct(?int $retailer_id)
+    {
+        $this->retailer_id = $retailer_id;
+    }
+
+    /**
+     * Determine if the validation rule passes.
+     *
+     * @param  string  $attribute
+     * @param  mixed  $value
+     * @return bool
+     */
+    public function passes($attribute, $value)
+    {
+        $product = Product::where('sku', $value)->where('retailer_id', $this->retailer_id)->get();
+        return (count($product) === 0) ? true : false;
+
+    }
+
+    /**
+     * Get the validation error message.
+     *
+     * @return string
+     */
+    public function message()
+    {
+        return 'This sku is already in use.';
+    }
+}