Allow null values for enums

src/Executor/Values.php

@@ -247,7 +247,7 @@ class Values
                 // Scalar/Enum input checks to ensure the type can parse the value to
                 // a non-null value.
                 $parseResult = $type->parseValue($value);
-                if (null === $parseResult) {
+                if (null === $parseResult && !$type->isValidValue($value)) {
                     $v = Utils::printSafe($value);
                     return [
                         "Expected type \"{$type->name}\", found $v."

src/Type/Definition/EnumType.php

@@ -91,6 +91,24 @@ class EnumType extends Type implements InputType, OutputType, LeafType
         return isset($lookup[$value]) ? $lookup[$value]->name : null;
     }
 
+    /**
+     * @param string $value
+     * @return bool
+     */
+    public function isValidValue($value)
+    {
+        return is_string($value) && $this->getNameLookup()->offsetExists($value);
+    }
+
+    /**
+     * @param $valueNode
+     * @return bool
+     */
+    public function isValidLiteral($valueNode)
+    {
+        return $valueNode instanceof EnumValueNode && $this->getNameLookup()->offsetExists($valueNode->value);
+    }
+
     /**
      * @param $value
      * @return null

src/Type/Definition/LeafType.php

@@ -31,4 +31,16 @@ interface LeafType
      * @return mixed
      */
     public function parseLiteral($valueNode);
+
+    /**
+     * @param string $value
+     * @return bool
+     */
+    public function isValidValue($value);
+
+    /**
+     * @param \GraphQL\Language\AST\Node $valueNode
+     * @return mixed
+     */
+    public function isValidLiteral($valueNode);
 }

src/Type/Definition/ScalarType.php

@@ -34,4 +34,28 @@ abstract class ScalarType extends Type implements OutputType, InputType, LeafTyp
 
         Utils::assertValidName($this->name);
     }
+
+    /**
+     * Determines if an internal value is valid for this type.
+     * Equivalent to checking for if the parsedValue is nullish.
+     *
+     * @param $value
+     * @return bool
+     */
+    public function isValidValue($value)
+    {
+        return null !== $this->parseValue($value);
+    }
+
+    /**
+     * Determines if an internal value is valid for this type.
+     * Equivalent to checking for if the parsedLiteral is nullish.
+     *
+     * @param $valueNode
+     * @return bool
+     */
+    public function isValidLiteral($valueNode)
+    {
+        return null !== $this->parseLiteral($valueNode);
+    }
 }

src/Utils/AST.php

@@ -307,9 +307,9 @@ class AST
         if ($type instanceof LeafType) {
             $parsed = $type->parseLiteral($valueNode);
 
-            if (null === $parsed) {
-                // null represent a failure to parse correctly,
-                // in which case no value is returned.
+            if (null === $parsed && !$type->isValidLiteral($valueNode)) {
+                // Invalid values represent a failure to parse correctly, in which case
+                // no value is returned.
                 return $undefined;
             }
 

src/Utils/MixedStore.php

@@ -43,6 +43,16 @@ class MixedStore implements \ArrayAccess
      */
     private $lastArrayValue;
 
+    /**
+     * @var mixed
+     */
+    private $nullValue;
+
+    /**
+     * @var bool
+     */
+    private $nullValueIsSet = false;
+
     /**
      * MixedStore constructor.
      */
@@ -83,6 +93,9 @@ class MixedStore implements \ArrayAccess
                 }
             }
         }
+        if (null === $offset) {
+            return $this->nullValueIsSet;
+        }
         return false;
     }
 
@@ -114,6 +127,9 @@ class MixedStore implements \ArrayAccess
                 }
             }
         }
+        if (null === $offset) {
+            return $this->nullValue;
+        }
         return null;
     }
 
@@ -138,6 +154,9 @@ class MixedStore implements \ArrayAccess
         } else if (is_array($offset)) {
             $this->arrayKeys[] = $offset;
             $this->arrayValues[] = $value;
+        } else if (null === $offset) {
+            $this->nullValue = $value;
+            $this->nullValueIsSet = true;
         } else {
             throw new \InvalidArgumentException("Unexpected offset type: " . Utils::printSafe($offset));
         }
@@ -165,6 +184,9 @@ class MixedStore implements \ArrayAccess
                 array_splice($this->arrayKeys, $index, 1);
                 array_splice($this->arrayValues, $index, 1);
             }
+        } else if (null === $offset) {
+            $this->nullValue = null;
+            $this->nullValueIsSet = false;
         }
     }
 }

src/Validator/DocumentValidator.php

@@ -1,22 +1,16 @@
 <?php
 namespace GraphQL\Validator;
 
-use GraphQL\Error\Error;
 use GraphQL\Error\InvariantViolation;
 use GraphQL\Language\AST\ListValueNode;
 use GraphQL\Language\AST\DocumentNode;
-use GraphQL\Language\AST\FragmentSpreadNode;
-use GraphQL\Language\AST\Node;
 use GraphQL\Language\AST\NodeKind;
 use GraphQL\Language\AST\NullValueNode;
-use GraphQL\Language\AST\ValueNode;
 use GraphQL\Language\AST\VariableNode;
 use GraphQL\Language\Printer;
 use GraphQL\Language\Visitor;
-use GraphQL\Language\VisitorOperation;
 use GraphQL\Schema;
 use GraphQL\Type\Definition\InputObjectType;
-use GraphQL\Type\Definition\InputType;
 use GraphQL\Type\Definition\LeafType;
 use GraphQL\Type\Definition\ListOfType;
 use GraphQL\Type\Definition\NonNull;
@@ -231,11 +225,8 @@ class DocumentValidator
         }
 
         if ($type instanceof LeafType) {
-            // Scalar/Enum input checks to ensure the type can parse the value to
-            // a non-null value.
-            $parseResult = $type->parseLiteral($valueNode);
-
-            if (null === $parseResult) {
+            // Scalars must parse to a non-null value
+            if (!$type->isValidLiteral($valueNode)) {
                 $printed = Printer::doPrint($valueNode);
                 return [ "Expected type \"{$type->name}\", found $printed." ];
             }

tests/Utils/ValueFromAstTest.php

@@ -72,6 +72,7 @@ class ValueFromAstTest extends \PHPUnit_Framework_TestCase
                 'RED' => ['value' => 1],
                 'GREEN' => ['value' => 2],
                 'BLUE' => ['value' => 3],
+                'NULL' => ['value' => null],
             ]
         ]);
 
@@ -80,6 +81,7 @@ class ValueFromAstTest extends \PHPUnit_Framework_TestCase
         $this->runTestCase($testEnum, '3', Utils::undefined());
         $this->runTestCase($testEnum, '"BLUE"', Utils::undefined());
         $this->runTestCase($testEnum, 'null', null);
+        $this->runTestCase($testEnum, 'NULL', null);
     }
 
     /**

tests/Validator/ArgumentsOfCorrectTypeTest.php

@@ -132,6 +132,20 @@ class ArgumentsOfCorrectTypeTest extends TestCase
         ');
     }
 
+    /**
+     * @it Enum with null value
+     */
+    public function testEnumWithNullValue()
+    {
+        $this->expectPassesRule(new ArgumentsOfCorrectType(), '
+        {
+          complicatedArgs {
+            enumArgField(enumArg: NO_FUR)
+          }
+        }
+        ');
+    }
+
     /**
      * @it null into nullable type
      */

tests/Validator/TestCase.php

@@ -183,6 +183,7 @@ abstract class TestCase extends \PHPUnit_Framework_TestCase
                 'BLACK' => [ 'value' => 1 ],
                 'TAN' => [ 'value' => 2 ],
                 'SPOTTED' => [ 'value' => 3 ],
+                'NO_FUR' => [ 'value' => null ],
             ],
         ]);