add ArrayToJson transformeter

Author: xthiago

Form/DataTransformer/ArrayToJsonTransformer.php

@@ -0,0 +1,74 @@
+<?php
+
+namespace Xthiago\FormExtraBundle\Form\DataTransformer;
+
+use Symfony\Component\Form\DataTransformerInterface;
+use Symfony\Component\Form\Exception\TransformationFailedException;
+
+/**
+ * Transforms between a JSON string and an associative array.
+ *
+ * @author Thiago Rodrigues <xthiago@gmail.com>
+ */
+class ArrayToJsonTransformer implements DataTransformerInterface
+{
+    /**
+     * Constructor
+     *
+     */
+    public function __construct()
+    {
+    }
+
+    /**
+     * Transforms an array into a JSON string
+     *
+     * @param array $array Array to transform
+     *
+     * @return string
+     *
+     * @throws TransformationFailedException If the given value is not an array
+     */
+    public function transform($array)
+    {
+        if (null === $array) {
+            return '';
+        }
+
+        if (!is_array($array)) {
+            throw new TransformationFailedException('Expected an array.');
+        }
+
+        $string = json_encode($array);
+
+        return $string;
+    }
+
+    /**
+     * Transforms a JSON string into an array
+     *
+     * @param string $string String to transform
+     *
+     * @return array
+     *
+     * @throws TransformationFailedException If the given value is not a string
+     */
+    public function reverseTransform($string)
+    {
+        if (null !== $string && !is_string($string)) {
+            throw new TransformationFailedException('Expected a string.');
+        }
+
+        if (empty($string)) {
+            return array();
+        }
+
+        $values = json_decode($string, true);
+
+        if (0 === count($values)) {
+            return array();
+        }
+
+        return $values;
+    }
+}