ISSUE-345: validate that template has placeholder

Author: tatevikg1

config/services/validators.yml

@@ -26,3 +26,6 @@ services:
   PhpList\RestBundle\Validator\TemplateImageValidator:
     autowire: true
     autoconfigure: true
+
+  PhpList\RestBundle\Validator\ContainsPlaceholderValidator:
+    tags: ['validator.constraint_validator']

src/Entity/Request/CreateTemplateRequest.php

@@ -6,6 +6,7 @@
 
 use Symfony\Component\HttpFoundation\File\UploadedFile;
 use Symfony\Component\Validator\Constraints as Assert;
+use PhpList\RestBundle\Validator as CustomAssert;
 
 class CreateTemplateRequest
 {
@@ -14,8 +15,10 @@ class CreateTemplateRequest
     public string $title;
 
     #[Assert\NotBlank]
+    #[CustomAssert\ContainsPlaceholder]
     public string $content;
 
+    #[CustomAssert\ContainsPlaceholder]
     public ?string $text = null;
 
     public ?UploadedFile $file = null;

src/Validator/ContainsPlaceholder.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpList\RestBundle\Validator;
+
+use Symfony\Component\Validator\Constraint;
+
+#[\Attribute(\Attribute::TARGET_PROPERTY | \Attribute::TARGET_METHOD | \Attribute::IS_REPEATABLE)]
+class ContainsPlaceholder extends Constraint
+{
+    public string $placeholder = '[CONTENT]';
+    public string $message = 'The content must include at least one "{{ placeholder }}" placeholder.';
+}

src/Validator/ContainsPlaceholderValidator.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpList\RestBundle\Validator;
+
+use InvalidArgumentException;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+
+class ContainsPlaceholderValidator extends ConstraintValidator
+{
+    public function validate($value, Constraint $constraint): void
+    {
+        if (!$constraint instanceof ContainsPlaceholder) {
+            throw new InvalidArgumentException(sprintf('%s expects %s.', __CLASS__, ContainsPlaceholder::class));
+        }
+
+        if (null === $value || '' === $value) {
+            return;
+        }
+
+        if (!str_contains($value, $constraint->placeholder)) {
+            $this->context->buildViolation($constraint->message)
+                ->setParameter('{{ placeholder }}', $constraint->placeholder)
+                ->addViolation();
+        }
+    }
+}