Moved the setInvalidMessage() from data mappers to data transformers

Author: javiereguiluz

form/data_mappers.rst

@@ -88,7 +88,6 @@ in your form type::
     use App\Painting\Color;
     use Symfony\Component\Form\AbstractType;
     use Symfony\Component\Form\DataMapperInterface;
-    use Symfony\Component\Form\Exception\TransformationFailedException;
     use Symfony\Component\Form\Exception\UnexpectedTypeException;
     use Symfony\Component\Form\FormInterface;
 
@@ -125,17 +124,6 @@ in your form type::
             /** @var FormInterface[] $forms */
             $forms = iterator_to_array($forms);
 
-            // optionally you can validate the data to throw more precise exception errors
-            $redComponent = $forms['red']->getData();
-            if (!\is_numeric($redComponent) || $redComponent < 0 || $redComponent > 255) {
-                $failure = new TransformationFailedException('Expected a RGB color component.');
-                $failure->setInvalidMessage('Color components should be numeric values in the [0-255] range. {{ value }} is invalid.', [
-                    '{{ value }}' => $redComponent,
-                ]);
-
-                throw $failure;
-            }
-
             // as data is passed by reference, overriding it will change it in
             // the form object as well
             // beware of type inconsistency, see caution below
@@ -147,10 +135,6 @@ in your form type::
         }
     }
 
-.. versionadded:: 4.3
-
-    The ``setInvalidMessage()`` method was introduced in Symfony 4.3.
-
 .. caution::
 
     The data passed to the mapper is *not yet validated*. This means that your

form/data_transformers.rst

@@ -291,6 +291,44 @@ and type-hint the new class::
         // ...
     }
 
+Instead of defining the same ``invalid_message`` every time the form type is
+used, you can set the end-user error message in the data transformer using the
+``setInvalidMessage()`` method::
+
+    // src/Form/DataTransformer/IssueToNumberTransformer.php
+    namespace App\Form\DataTransformer;
+
+    use Symfony\Component\Form\DataTransformerInterface;
+    use Symfony\Component\Form\Exception\TransformationFailedException;
+
+    class IssueToNumberTransformer implements DataTransformerInterface
+    {
+        // ...
+
+        public function reverseTransform($issueNumber)
+        {
+            // ...
+
+            if (null === $issue) {
+                $privateErrorMessage = sprintf('An issue with number "%s" does not exist!', $issueNumber);
+                $publicErrorMessage = 'The given "{{ value }}" value is not a valid issue number.';
+
+                $failure = new TransformationFailedException($privateErrorMessage);
+                $failure->setInvalidMessage($publicErrorMessage, [
+                    '{{ value }}' => $issueNumber,
+                ]);
+
+                throw $failure;
+            }
+
+            return $issue;
+        }
+    }
+
+.. versionadded:: 4.3
+
+    The ``setInvalidMessage()`` method was introduced in Symfony 4.3.
+
 That's it! As long as you're using :ref:`autowire <services-autowire>` and
 :ref:`autoconfigure <services-autoconfigure>`, Symfony will automatically
 know to pass your ``TaskType`` an instance of the ``IssueToNumberTransformer``.