Add JSON scalar

Author: spawnia

README.md

@@ -26,6 +26,10 @@ This package comes with a bunch of scalars that are ready-to-use and just work o
 
 A [RFC 5321](https://tools.ietf.org/html/rfc5321) compliant email.
 
+### [JSON](src/JSON.php)
+
+Arbitrary data encoded in JavaScript Object Notation. See https://www.json.org/.
+
 ### [Mixed](src/Mixed.php)
 
 Loose type that allows any value. Be careful when passing in large `Int` or `Float` literals,

composer.json

@@ -14,7 +14,8 @@
     "php": ">=7.1",
     "webonyx/graphql-php": "^0.13",
     "spatie/regex": "^1.3",
-    "egulias/email-validator": "^2.1"
+    "egulias/email-validator": "^2.1",
+    "thecodingmachine/safe": "^0.1.14"
   },
   "require-dev": {
     "ext-json": "*",

src/JSON.php

@@ -0,0 +1,95 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MLL\GraphQLScalars;
+
+use Exception;
+use GraphQL\Error\Error;
+use GraphQL\Language\AST\Node;
+use GraphQL\Type\Definition\ScalarType;
+use GraphQL\Utils\Utils;
+use Safe\Exceptions\JsonException;
+
+class JSON extends ScalarType
+{
+    /**
+     * The description that is used for schema introspection.
+     *
+     * @var string
+     */
+    public $description = 'Arbitrary data encoded in JavaScript Object Notation. See https://www.json.org/.';
+
+    /**
+     * Serializes an internal value to include in a response.
+     *
+     * @param mixed $value
+     *
+     * @return string
+     */
+    public function serialize($value): string
+    {
+        return \Safe\json_encode($value);
+    }
+
+    /**
+     * Parses an externally provided value (query variable) to use as an input
+     *
+     * In the case of an invalid value this method must throw an Exception
+     *
+     * @param mixed $value
+     *
+     * @return mixed
+     *
+     * @throws Error
+     */
+    public function parseValue($value)
+    {
+        return $this->decodeJSON($value);
+    }
+
+    /**
+     * Parses an externally provided literal value (hardcoded in GraphQL query) to use as an input
+     *
+     * In the case of an invalid node or value this method must throw an Exception
+     *
+     * @param Node $valueNode
+     * @param mixed[]|null $variables
+     *
+     * @return mixed
+     *
+     * @throws Exception
+     */
+    public function parseLiteral($valueNode, ?array $variables = null)
+    {
+        if(!property_exists($valueNode, 'value')){
+            throw new Error(
+                'Can only parse literals that contain a value, got ' . Utils::printSafeJson($valueNode)
+            );
+        }
+
+        return $this->decodeJSON($valueNode->value);
+    }
+
+    /**
+     * Try to decode a user-given value into JSON.
+     *
+     * @param mixed $value
+     *
+     * @return mixed
+     *
+     * @throws Error
+     */
+    protected function decodeJSON($value)
+    {
+        try {
+            $parsed = \Safe\json_decode($value);
+        } catch (JsonException $jsonException) {
+            throw new Error(
+                $jsonException->getMessage()
+            );
+        }
+
+        return $parsed;
+    }
+}

tests/JSONTest.php

@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests;
+
+use GraphQL\Error\Error;
+use GraphQL\Language\AST\StringValueNode;
+use MLL\GraphQLScalars\JSON;
+use PHPUnit\Framework\TestCase;
+use Safe\Exceptions\JsonException;
+
+class JSONTest extends TestCase
+{
+    const INVALID_UTF8_SEQUENCE = "\xB1\x31";
+
+    public function testSerializeThrowsIfNonEncodableValueIsGiven(): void
+    {
+        $this->expectException(JsonException::class);
+
+        (new JSON())->serialize(self::INVALID_UTF8_SEQUENCE);
+    }
+
+    public function testSerializeThrowsIfJSONIsInvalid(): void
+    {
+        $this->expectException(JsonException::class);
+
+        (new JSON())->serialize(self::INVALID_UTF8_SEQUENCE);
+    }
+
+    public function testSerializePassesWhenJSONIsValid(): void
+    {
+        $serializedResult = (new JSON())->serialize(1);
+
+        $this->assertSame('1', $serializedResult);
+    }
+
+    public function testParseValueThrowsIfJSONIsInvalid(): void
+    {
+        $this->expectException(Error::class);
+
+        (new JSON())->parseValue('foo');
+    }
+
+    public function testParseValuePassesIfJSONIsValid(): void
+    {
+        $this->assertSame(
+            [1, 2],
+            (new JSON())->parseValue('[1, 2]')
+        );
+    }
+
+    public function testParseLiteralThrowsIfNotValidJSON(): void
+    {
+        $this->expectException(Error::class);
+
+        (new JSON())->parseLiteral(new StringValueNode(['value' => 'foo']));
+    }
+
+    public function testParseLiteralPassesIfJSONIsValid(): void
+    {
+        $this->assertSame(
+            'bar',
+            (new JSON())->parseLiteral(new StringValueNode(['value' => '{"foo": "bar"}']))->foo
+        );
+    }
+}