diff --git a/config/packages/validator.yaml b/config/packages/validator.yaml
index 0201281..caacdfe 100644
--- a/config/packages/validator.yaml
+++ b/config/packages/validator.yaml
@@ -1,6 +1,8 @@
 framework:
     validation:
         email_validation_mode: html5
+        enabled: true
+        translation_domain: validation_errors
 
         # Enables validator auto-mapping support.
         # For instance, basic validation constraints will be inferred from Doctrine's metadata.
diff --git a/src/Entity/QRCode/QRCode.php b/src/Entity/QRCode/QRCode.php
index f617b4f..6ff8408 100644
--- a/src/Entity/QRCode/QRCode.php
+++ b/src/Entity/QRCode/QRCode.php
@@ -2,30 +2,47 @@
 declare(strict_types=1);
 
 namespace App\Entity\QRCode;
+use Symfony\Component\Validator\Constraints as Assert;
 
 /**
  * QRCode description
  */
 class QRCode
 {
+    #[Assert\NotBlank]
+    #[Assert\Iban(
+        message: 'messages.not_a_iban_number',
+    )]
     private ?string $iban;
+    #[Assert\NotBlank(message: 'messages.fill_value')]
+    #[Assert\GreaterThanOrEqual(
+            'today', message: 'messages.invalid_date'
+    )]
     private ?\DateTime $dueDate;
+    #[Assert\NotBlank(message: 'messages.fill_value')]
     private ?string $message;
+
+    #[Assert\Valid]
+    #[Assert\NotBlank]
     private ?QRCodeMoney $money;
+    #[Assert\Valid]
+    #[Assert\NotBlank]
     private ?QRCodePaymentIdentification $paymentIdentification;
+    #[Assert\Valid]
+    #[Assert\NotBlank]
     private readonly QRCodeQROptions $codeQROptions;
 
     /**
      * @param QRCodeQROptions $codeQROptions
      * @param string|null $iban
-     * @param string|null $dueDate
+     * @param \DateTime|null $dueDate
      * @param string|null $message
      * @param QRCodeMoney|null $money
      */
     public function __construct(
         QRCodeQROptions $codeQROptions,
         ?string $iban = null,
-        ?string $dueDate = null,
+        ?\DateTime $dueDate = null,
         ?string $message = null,
         ?QRCodeMoney $money = null)
     {
diff --git a/src/Entity/QRCode/QRCodeMoney.php b/src/Entity/QRCode/QRCodeMoney.php
index 9dcb07d..96198ef 100644
--- a/src/Entity/QRCode/QRCodeMoney.php
+++ b/src/Entity/QRCode/QRCodeMoney.php
@@ -3,13 +3,22 @@ declare(strict_types=1);
 
 namespace App\Entity\QRCode;
 
+use App\Service\CurrencyListerInterface;
+use Symfony\Component\Validator\Constraints as Assert;
+
 /**
  * Money type for QR code
  */
 class QRCodeMoney
 {
+    #[Assert\Positive(
+        message: 'messages.not_valid_amount',
+    )]
+    #[Assert\NotBlank(message: 'messages.fill_value')]
     private ?string $amount;
 
+    // TODO: getCurrencies validation
+    #[Assert\NotBlank(message: 'messages.fill_value')]
     private ?string $currency;
 
     /**
diff --git a/src/Entity/QRCode/QRCodePaymentIdentification.php b/src/Entity/QRCode/QRCodePaymentIdentification.php
index c66d977..7845c08 100644
--- a/src/Entity/QRCode/QRCodePaymentIdentification.php
+++ b/src/Entity/QRCode/QRCodePaymentIdentification.php
@@ -3,12 +3,46 @@ declare(strict_types=1);
 
 namespace App\Entity\QRCode;
 
+use Symfony\Component\Validator\Constraints as Assert;
+
 /**
  * Payment identification for QR code
  */
 class QRCodePaymentIdentification {
+    #[Assert\NotBlank(message: 'messages.fill_value')]
+    #[Assert\Length( // <<< Ano, mohl jsem si napsat vlastni validator ...
+        min: 1,
+        max: 10,
+        minMessage: 'messages.not_variable_symbol',
+        maxMessage: 'messages.not_variable_symbol',
+    )] // https://en.wikipedia.org/wiki/Variable_symbol
+    #[Assert\Positive(
+        message: 'messages.not_variable_symbol',
+    )]
     private string $variableSymbol;
+
+    #[Assert\NotBlank(message: 'messages.fill_value')]
+    #[Assert\Length(
+        min: 1,
+        max: 10,
+        minMessage: 'messages.not_specific_symbol',
+        maxMessage: 'messages.not_specific_symbol',
+    )] // https://cs.wikipedia.org/wiki/Specifick%C3%BD_symbol
+    #[Assert\Positive(
+        message: 'The {{ value }} is not a variable symbol.',
+    )]
     private string $specificSymbol;
+
+    #[Assert\NotBlank(message: 'messages.fill_value')]
+    #[Assert\Length(
+        min: 1,
+        max: 10,
+        minMessage: 'messages.not_constant_symbol',
+        maxMessage: 'messages.not_constant_symbol',
+    )]  // https://www.hyponamiru.cz/en/glossary/constant-symbol/
+    #[Assert\Positive(
+        message: 'messages.not_constant_symbol',
+    )]
     private string $constantSymbol;
 
     public function getVariableSymbol(): string
diff --git a/src/Entity/QRCode/QRCodeQROptions.php b/src/Entity/QRCode/QRCodeQROptions.php
index 25fed77..ffa5888 100644
--- a/src/Entity/QRCode/QRCodeQROptions.php
+++ b/src/Entity/QRCode/QRCodeQROptions.php
@@ -3,11 +3,22 @@ declare(strict_types=1);
 
 namespace App\Entity\QRCode;
 
+use Symfony\Component\Validator\Constraints as Assert;
+
 /**
  * Options for generating QR code
  */
 readonly class QRCodeQROptions {
+    #[Assert\Positive(
+        message: 'messages.scale_must_be_positive',
+    )]
+    #[Assert\NotBlank(message: 'messages.fill_value')]
     private int $scale;
+    
+    #[Assert\PositiveOrZero(
+        message: 'messages.margin_must_be_positive',
+    )]
+    #[Assert\NotBlank(message: 'messages.fill_value')]
     private int $margin;
 
     /**
diff --git a/src/Form/Type/QRCodeType.php b/src/Form/Type/QRCodeType.php
index a113749..32987af 100644
--- a/src/Form/Type/QRCodeType.php
+++ b/src/Form/Type/QRCodeType.php
@@ -22,7 +22,7 @@ class QRCodeType extends AbstractType
             ->add('message', TextType::class)
             ->add('money', QRCodeMoneyType::class)
             ->add('paymentIdentification', QRCodePaymentIdentificationType::class)
-            ->add('save', SubmitType::class);
+            ->add('generate_qr_code', SubmitType::class);
     }
 
     public function configureOptions(OptionsResolver $resolver): void