Bug - Improve unique email validation

api/app/GraphQL/Validators/UpdateUserInputValidator.php

@@ -0,0 +1,44 @@
+<?php
+
+namespace App\GraphQL\Validators;
+
+use Illuminate\Validation\Rule;
+use Nuwave\Lighthouse\Validation\Validator;
+
+final class UpdateUserInputValidator extends Validator
+{
+    /**
+     * Return the validation rules.
+     *
+     * @return array<string, array<mixed>>
+     */
+    public function rules(): array
+    {
+        return [
+            'email' => [
+                'sometimes',
+                'nullable',
+                /**
+                 * Note: Ignore the email for the user passed
+                 * in when executing the mutation so it is not
+                 * included in the unique check. This is required
+                 * for allowing a user to be updated while the email
+                 * remains the same.
+                 *
+                 * REF: https://laravel.com/docs/9.x/validation#rule-unique
+                 */
+                Rule::unique('users', 'email')->ignore($this->arg('id'), 'id'),
+            ]
+        ];
+    }
+
+    /**
+     * Return the validation messages
+     */
+    public function messages(): array
+    {
+        return [
+            'email.unique' => 'This email address is already in use',
+        ];
+    }
+}