Digia\GraphQL\Execution\ExecutionStrategy

Complexity

Total Complexity

112

Size/Duplication

Total Lines	1082
Duplicated Lines	0 %

Importance

Changes

0

25 Methods

Rating	Name	Duplication	Size	Complexity
C	defaultFieldResolver()	0	25	7
A	__construct()	0	8	1
B	collectAndExecuteSubFields()	0	28	4
D	collectFields()	0	45	9
C	defaultTypeResolver()	0	44	11
A	completeLeafValue()	0	13	2
A	getFieldNameKey()	0	4	2
B	doesFragmentConditionMatch()	0	23	4
B	shouldIncludeNode()	0	20	5
B	completeObjectValue()	0	26	3
A	isPromise()	0	3	1
B	executeFields()	0	36	6
B	resolveField()	0	40	2
B	completeListValue()	0	32	6
C	completeValue()	0	76	11
B	executeFieldsSerially()	0	64	4
B	buildLocatedError()	0	12	5
B	completeValueCatchingError()	0	60	6
B	ensureValidRuntimeType()	0	42	6
A	completeValueWithLocatedError()	0	19	2
B	getFieldDefinition()	0	24	6
A	resolveFieldValueOrError()	0	16	2
A	determineResolveFunction()	0	15	3
A	buildResolveInfo()	0	19	1
A	completeAbstractValue()	0	53	3

<?php

namespace Digia\GraphQL\Execution;

use Digia\GraphQL\Error\ExecutionException;
use Digia\GraphQL\Error\GraphQLException;
use Digia\GraphQL\Error\InvalidTypeException;
use Digia\GraphQL\Error\UndefinedException;
use Digia\GraphQL\Language\Node\FieldNode;
use Digia\GraphQL\Language\Node\FragmentDefinitionNode;
use Digia\GraphQL\Language\Node\FragmentSpreadNode;
use Digia\GraphQL\Language\Node\InlineFragmentNode;
use Digia\GraphQL\Language\Node\NodeInterface;
use Digia\GraphQL\Language\Node\OperationDefinitionNode;
use Digia\GraphQL\Language\Node\SelectionSetNode;
use Digia\GraphQL\Schema\Schema;
use Digia\GraphQL\Type\Definition\AbstractTypeInterface;
use Digia\GraphQL\Type\Definition\Field;
use Digia\GraphQL\Type\Definition\InterfaceType;
use Digia\GraphQL\Type\Definition\LeafTypeInterface;
use Digia\GraphQL\Type\Definition\ListType;
use Digia\GraphQL\Type\Definition\NonNullType;
use Digia\GraphQL\Type\Definition\ObjectType;
use Digia\GraphQL\Type\Definition\TypeInterface;
use Digia\GraphQL\Type\Definition\UnionType;
use React\Promise\ExtendedPromiseInterface;
use React\Promise\PromiseInterface;
use function Digia\GraphQL\Type\SchemaMetaFieldDefinition;
use function Digia\GraphQL\Type\TypeMetaFieldDefinition;
use function Digia\GraphQL\Type\TypeNameMetaFieldDefinition;
use function Digia\GraphQL\Util\toString;
use function Digia\GraphQL\Util\typeFromAST;

/**
 * Class AbstractStrategy
 *
 * @package Digia\GraphQL\Execution\Strategies
 */
abstract class ExecutionStrategy
{

    /**
     * @var array
     */
    protected static $defaultFieldResolver = [
        __CLASS__,
        'defaultFieldResolver',
    ];

    /**
     * @var ExecutionContext
     */
    protected $context;

    /**
     * @var OperationDefinitionNode
     */
    protected $operation;

    /**
     * @var mixed
     */
    protected $rootValue;

    /**
     * @var array
     */
    protected $finalResult;

    /**
     * AbstractStrategy constructor.
     *
     * @param ExecutionContext $context
     *
     * @param OperationDefinitionNode $operation
     */
    public function __construct(
        ExecutionContext $context,
        OperationDefinitionNode $operation,
        $rootValue
    ) {
        $this->context = $context;
        $this->operation = $operation;
        $this->rootValue = $rootValue;
    }

    /**
     * Try to resolve a field without any field resolver function.
     *
     * @param array|object $rootValue
     * @param              $args
     * @param              $context
     * @param ResolveInfo $info
     *
     * @return mixed|null
     */
    public static function defaultFieldResolver(
        $rootValue,
        $args,
        $context,
        ResolveInfo $info
    ) {
        $fieldName = $info->getFieldName();
        $property = null;

        if (is_array($rootValue) && isset($rootValue[$fieldName])) {
            $property = $rootValue[$fieldName];
        }

        if (is_object($rootValue)) {
            $getter = 'get'.ucfirst($fieldName);
            if (method_exists($rootValue, $getter)) {
                $property = $rootValue->{$getter}();
            } elseif (property_exists($rootValue, $fieldName)) {
                $property = $rootValue->{$fieldName};
            }
        }


        return $property instanceof \Closure ? $property($rootValue, $args,
            $context, $info) : $property;
    }

    /**
     * @return array|null
     */
    abstract function execute(): ?array;

It is generally recommended to explicitly declare the visibility for methods.

    /**
     * Implements the "Evaluating selection sets" section of the spec for
     * "write" mode.
     *
     * @param ObjectType $objectType
     * @param            $rootValue
     * @param            $path
     * @param            $fields
     *
     * @return array
     * @throws InvalidTypeException
     * @throws \Digia\GraphQL\Error\ExecutionException
     * @throws \Digia\GraphQL\Error\InvariantException
     * @throws \Throwable
     */
    public function executeFieldsSerially(
        ObjectType $objectType,
        $rootValue,
        $path,
        $fields
    ) {

        $finalResults = [];

        $promise = new \React\Promise\FulfilledPromise([]);

        $resolve = function (
            $results,
            $fieldName,
            $path,
            $objectType,
            $rootValue,
            $fieldNodes
        ) {
            $fieldPath = $path;
            $fieldPath[] = $fieldName;
            try {
                $result = $this->resolveField($objectType, $rootValue,

Are you sure the assignment to $result is correct as $this->resolveField($objectType, $rootValue, $fieldNodes, $fieldPath) targeting Digia\GraphQL\Execution\ExecutionStrategy::resolveField() seems to always return null.

                    $fieldNodes, $fieldPath);
            } catch (UndefinedException $ex) {
                return null;
            }

            if ($this->isPromise($result)) {
                /** @var ExtendedPromiseInterface $result */
                return $result->then(function ($resolvedResult) use (
                    $fieldName,
                    $results
                ) {
                    $results[$fieldName] = $resolvedResult;

                    return $results;
                });
            }

            $results[$fieldName] = $result;

            return $results;
        };

        foreach ($fields as $fieldName => $fieldNodes) {
            $promise = $promise->then(function ($resolvedResults) use (
                $resolve,
                $fieldName,
                $path,
                $objectType,
                $rootValue,
                $fieldNodes
            ) {
                return $resolve($resolvedResults, $fieldName, $path,
                    $objectType, $rootValue, $fieldNodes);
            });
        }

        $promise->then(function ($resolvedResults) use (&$finalResults) {
            $finalResults = $resolvedResults ?? [];
        });

        return $finalResults;
    }

    /**
     * @param ObjectType $parentType
     * @param            $rootValue
     * @param            $fieldNodes
     * @param            $path
     *
     * @return array|null|\Throwable
     * @throws InvalidTypeException
     * @throws \Digia\GraphQL\Error\ExecutionException
     * @throws \Digia\GraphQL\Error\InvariantException
     * @throws \Throwable
     */
    protected function resolveField(
        ObjectType $parentType,
        $rootValue,
        $fieldNodes,
        $path
    ) {
        /** @var FieldNode $fieldNode */
        $fieldNode = $fieldNodes[0];

        $field = $this->getFieldDefinition($this->context->getSchema(),
            $parentType, $fieldNode->getNameValue());

        if (null === $field) {
            throw new UndefinedException('Undefined field definition.');
        }

        $info = $this->buildResolveInfo($fieldNodes, $fieldNode, $field,
            $parentType, $path, $this->context);

        $resolveFunction = $this->determineResolveFunction($field, $parentType,
            $this->context);

        $result = $this->resolveFieldValueOrError(
            $field,
            $fieldNode,
            $resolveFunction,
            $rootValue,
            $this->context,
            $info
        );

        $result = $this->completeValueCatchingError(

Are you sure the assignment to $result is correct as $this->completeValueCatchingError($field->getType(), $fieldNodes, $info, $path, $result) targeting Digia\GraphQL\Execution\ExecutionStrategy::completeValueCatchingError() seems to always return null.

            $field->getType(),
            $fieldNodes,
            $info,
            $path,
            $result// $result is passed as $source
        );

        return $result;
    }

    /**
     * @param Schema $schema
     * @param ObjectType $parentType
     * @param string $fieldName
     *
     * @return \Digia\GraphQL\Type\Definition\Field|null
     * @throws InvalidTypeException
     * @throws \Digia\GraphQL\Error\InvariantException
     */
    public function getFieldDefinition(
        Schema $schema,
        ObjectType $parentType,
        string $fieldName
    ) {
        $schemaMetaFieldDefinition = SchemaMetaFieldDefinition();
        $typeMetaFieldDefinition = TypeMetaFieldDefinition();
        $typeNameMetaFieldDefinition = TypeNameMetaFieldDefinition();

        if ($fieldName === $schemaMetaFieldDefinition->getName() && $schema->getQueryType() === $parentType) {
            return $schemaMetaFieldDefinition;
        }

        if ($fieldName === $typeMetaFieldDefinition->getName() && $schema->getQueryType() === $parentType) {
            return $typeMetaFieldDefinition;
        }

        if ($fieldName === $typeNameMetaFieldDefinition->getName()) {
            return $typeNameMetaFieldDefinition;
        }

        $fields = $parentType->getFields();

        return $fields[$fieldName] ?? null;
    }

    /**
     * @param array $fieldNodes
     * @param FieldNode $fieldNode
     * @param Field $field
     * @param ObjectType $parentType
     * @param array|null $path
     * @param ExecutionContext $context
     *
     * @return ResolveInfo
     */
    private function buildResolveInfo(
        array $fieldNodes,
        FieldNode $fieldNode,
        Field $field,
        ObjectType $parentType,
        ?array $path,
        ExecutionContext $context
    ) {
        return new ResolveInfo(
            $fieldNode->getNameValue(),
            $fieldNodes,
            $field->getType(),
            $parentType,
            $path,
            $context->getSchema(),
            $context->getFragments(),
            $context->getRootValue(),
            $context->getOperation(),
            $context->getVariableValues()
        );
    }

    /**
     * @param Field $field
     * @param ObjectType $objectType
     * @param ExecutionContext $context
     *
     * @return callable|mixed|null
     */
    private function determineResolveFunction(
        Field $field,
        ObjectType $objectType,
        ExecutionContext $context
    ) {

        if ($field->hasResolve()) {
            return $field->getResolve();
        }

        if ($objectType->hasResolve()) {
            return $objectType->getResolve();
        }

        return $this->context->getFieldResolver() ?? self::$defaultFieldResolver;
    }

    /**
     * @param Field $field
     * @param FieldNode $fieldNode
     * @param callable $resolveFunction
     * @param                  $rootValue
     * @param ExecutionContext $context
     * @param ResolveInfo $info
     *
     * @return array|\Throwable
     */
    private function resolveFieldValueOrError(
        Field $field,
        FieldNode $fieldNode,
        ?callable $resolveFunction,
        $rootValue,
        ExecutionContext $context,
        ResolveInfo $info
    ) {
        try {
            $args = coerceArgumentValues($field, $fieldNode,
                $context->getVariableValues());

            return $resolveFunction($rootValue, $args,
                $context->getContextValue(), $info);
        } catch (\Throwable $error) {
            return $error;
        }
    }

    /**
     * @param TypeInterface $fieldType
     * @param               $fieldNodes
     * @param ResolveInfo $info
     * @param               $path
     * @param               $result
     *
     * @return null
     * @throws \Throwable
     */
    public function completeValueCatchingError(
        TypeInterface $fieldType,
        $fieldNodes,
        ResolveInfo $info,
        $path,
        &$result
    ) {
        if ($fieldType instanceof NonNullType) {
            return $this->completeValueWithLocatedError(

The expression return $this->completeValueWithLocatedError($fieldType, $fieldNodes, $info, $path, $result) also could return the type array which is incompatible with the documented return type null.

                $fieldType,
                $fieldNodes,
                $info,
                $path,
                $result
            );
        }

        try {
            $completed = $this->completeValueWithLocatedError(

Are you sure the assignment to $completed is correct as $this->completeValueWithLocatedError($fieldType, $fieldNodes, $info, $path, $result) targeting Digia\GraphQL\Execution\ExecutionStrategy::completeValueWithLocatedError() seems to always return null.

                $fieldType,
                $fieldNodes,
                $info,
                $path,
                $result
            );

            if ($this->isPromise($completed)) {
                $context = $this->context;

                /** @var ExtendedPromiseInterface $completed */
                return $completed->then(null,

The expression return $completed->then(null, function(...) { /* ... */ }) returns the type React\Promise\PromiseInterface which is incompatible with the documented return type null.

                    function ($error) use ($context, $fieldNodes, $path) {
                        //@TODO Handle $error better
                        if ($error instanceof \Exception) {
                            $context->addError($this->buildLocatedError($error,
                                $fieldNodes, $path));
                        } else {
                            $context->addError(
                                $this->buildLocatedError(
                                    new ExecutionException($error ?? 'An unknown error occurred.'),
                                    $fieldNodes,
                                    $path
                                )
                            );
                        }

                        return new \React\Promise\FulfilledPromise(null);
                    });
            }

            return $completed;
        } catch (ExecutionException $ex) {
            $this->context->addError($ex);

            return null;
        } catch (\Exception $ex) {
            $this->context->addError($this->buildLocatedError($ex, $fieldNodes,
                $path));

            return null;
        }
    }

    /**
     * @param TypeInterface $fieldType
     * @param               $fieldNodes
     * @param ResolveInfo $info
     * @param               $path
     * @param               $result
     *
     * @throws \Throwable
     */
    public function completeValueWithLocatedError(
        TypeInterface $fieldType,
        $fieldNodes,
        ResolveInfo $info,
        $path,
        $result
    ) {
        try {
            $completed = $this->completeValue(
                $fieldType,
                $fieldNodes,
                $info,
                $path,
                $result
            );

            return $completed;
        } catch (\Throwable $ex) {
            throw $this->buildLocatedError($ex, $fieldNodes, $path);
        }
    }

    /**
     * @param TypeInterface $returnType
     * @param               $fieldNodes
     * @param ResolveInfo $info
     * @param               $path
     * @param               $result
     *
     * @return array|mixed
     * @throws ExecutionException
     * @throws \Throwable
     */
    private function completeValue(
        TypeInterface $returnType,
        $fieldNodes,
        ResolveInfo $info,
        $path,
        &$result
    ) {
        if ($this->isPromise($result)) {
            /** @var ExtendedPromiseInterface $result */
            return $result->then(function (&$value) use (
                $returnType,
                $fieldNodes,
                $info,
                $path
            ) {
                return $this->completeValue($returnType, $fieldNodes, $info,
                    $path, $value);
            });
        }

        if ($result instanceof \Throwable) {
            throw $result;
        }

        // If result is null-like, return null.
        if (null === $result) {
            return null;
        }

        if ($returnType instanceof NonNullType) {
            $completed = $this->completeValue(
                $returnType->getOfType(),
                $fieldNodes,
                $info,
                $path,
                $result
            );

            if ($completed === null) {
                throw new ExecutionException(
                    sprintf(
                        'Cannot return null for non-nullable field %s.%s.',
                        $info->getParentType(), $info->getFieldName()
                    )
                );
            }

            return $completed;
        }

        // If field type is List, complete each item in the list with the inner type
        if ($returnType instanceof ListType) {
            return $this->completeListValue($returnType, $fieldNodes, $info,
                $path, $result);
        }


        // If field type is Scalar or Enum, serialize to a valid value, returning
        // null if serialization is not possible.
        if ($returnType instanceof LeafTypeInterface) {
            return $this->completeLeafValue($returnType, $result);
        }

        //@TODO Make a function for checking abstract type?
        if ($returnType instanceof InterfaceType || $returnType instanceof UnionType) {
            return $this->completeAbstractValue($returnType, $fieldNodes, $info,
                $path, $result);
        }

        // Field type must be Object, Interface or Union and expect sub-selections.
        if ($returnType instanceof ObjectType) {
            return $this->completeObjectValue($returnType, $fieldNodes, $info,
                $path, $result);
        }

        throw new ExecutionException("Cannot complete value of unexpected type \"{$returnType}\".");
    }

    /**
     * @param $value
     *
     * @return bool
     */
    protected function isPromise($value): bool
    {
        return $value instanceof ExtendedPromiseInterface;
    }

    /**
     * @param ListType $returnType
     * @param             $fieldNodes
     * @param ResolveInfo $info
     * @param             $path
     * @param             $result
     *
     * @return array|\React\Promise\Promise
     * @throws \Throwable
     */
    private function completeListValue(
        ListType $returnType,
        $fieldNodes,
        ResolveInfo $info,
        $path,
        &$result
    ) {
        $itemType = $returnType->getOfType();

        $completedItems = [];
        $containsPromise = false;

        if (!is_array($result) && !($result instanceof \Traversable)) {
            throw new \Exception(
                sprintf(
                    'Expected Array or Traversable, but did not find one for field %s.%s.',
                    $info->getParentType()->getName(),
                    $info->getFieldName()
                )
            );
        }

        foreach ($result as $key => $item) {
            $fieldPath = $path;
            $fieldPath[] = $key;
            $completedItem = $this->completeValueCatchingError($itemType,

Are you sure the assignment to $completedItem is correct as $this->completeValueCatchingError($itemType, $fieldNodes, $info, $fieldPath, $item) targeting Digia\GraphQL\Execution\ExecutionStrategy::completeValueCatchingError() seems to always return null.

                $fieldNodes, $info, $fieldPath, $item);
            $completedItems[] = $completedItem;
            $containsPromise = $containsPromise || $this->isPromise($completedItem);
        }

        return $containsPromise ? \React\Promise\all($completedItems) : $completedItems;
    }

    /**
     * @param LeafTypeInterface $returnType
     * @param                   $result
     *
     * @return mixed
     * @throws ExecutionException
     */
    private function completeLeafValue(LeafTypeInterface $returnType, &$result)
    {
        $serializedResult = $returnType->serialize($result);

The method serialize() does not exist on Digia\GraphQL\Type\Definition\LeafTypeInterface. Since it exists in all sub-types, consider adding an abstract or default implementation to Digia\GraphQL\Type\Definition\LeafTypeInterface.

        if ($serializedResult === null) {
            //@TODO Make a function for this type of exception
            throw new ExecutionException(
                sprintf('Expected value of type "%s" but received: %s.',
                    (string)$returnType, toString($result))
            );
        }

        return $serializedResult;
    }

    /**
     * @param AbstractTypeInterface $returnType
     * @param                       $fieldNodes
     * @param ResolveInfo $info
     * @param                       $path
     * @param                       $result
     *
     * @return array|PromiseInterface
     * @throws ExecutionException
     * @throws InvalidTypeException
     * @throws \Digia\GraphQL\Error\InvariantException
     * @throws \Throwable
     */
    private function completeAbstractValue(
        AbstractTypeInterface $returnType,
        $fieldNodes,
        ResolveInfo $info,
        $path,
        &$result
    ) {
        $runtimeType = $returnType->resolveType($result,
            $this->context->getContextValue(), $info);

$info of type Digia\GraphQL\Execution\ResolveInfo is incompatible with the type array expected by parameter $args of Digia\GraphQL\Type\Definition\AbstractTypeInterface::resolveType().

        if (null === $runtimeType) {
            //@TODO Show warning
            $runtimeType = $this->defaultTypeResolver($result,
                $this->context->getContextValue(), $info, $returnType);
        }

        if ($this->isPromise($runtimeType)) {
            /** @var ExtendedPromiseInterface $runtimeType */
            return $runtimeType->then(function ($resolvedRuntimeType) use (
                $returnType,
                $fieldNodes,
                $info,
                $path,
                &$result
            ) {
                return $this->completeObjectValue(
                    $this->ensureValidRuntimeType(
                        $resolvedRuntimeType,
                        $returnType,
                        $fieldNodes,
                        $info,
                        $result
                    ),
                    $fieldNodes,
                    $info,
                    $path,
                    $result
                );
            });
        }

        return $this->completeObjectValue(
            $this->ensureValidRuntimeType(
                $runtimeType,
                $returnType,
                $fieldNodes,
                $info,
                $result
            ),
            $fieldNodes,
            $info,
            $path,
            $result
        );
    }

    /**
     * @param                       $value
     * @param                       $context
     * @param ResolveInfo $info
     * @param AbstractTypeInterface $abstractType
     *
     * @return TypeInterface|null
     * @throws ExecutionException
     */
    private function defaultTypeResolver(
        $value,
        $context,
        ResolveInfo $info,
        AbstractTypeInterface $abstractType
    ) {
        $possibleTypes = $info->getSchema()->getPossibleTypes($abstractType);
        $promisedIsTypeOfResults = [];

        foreach ($possibleTypes as $index => $type) {
            $isTypeOfResult = $type->isTypeOf($value, $context, $info);
            if (null !== $isTypeOfResult) {
                if ($this->isPromise($isTypeOfResult)) {
                    $promisedIsTypeOfResults[$index] = $isTypeOfResult;
                    continue;
                }

                if ($isTypeOfResult === true) {
                    return $type;
                }

                if (\is_array($value)) {
                    //@TODO Make `type` configurable
                    if (isset($value['type']) && $value['type'] === $type->getName()) {
                        return $type;
                    }
                }
            }
        }

        if (!empty($promisedIsTypeOfResults)) {
            return \React\Promise\all($promisedIsTypeOfResults)

The expression return all($promisedIsTypeOfResults)->then(function(...) { /* ... */ }) also could return the type React\Promise\Promise which is incompatible with the documented return type null|Digia\GraphQL\Type\Definition\TypeInterface.

                ->then(function ($isTypeOfResults) use ($possibleTypes) {
                    foreach ($isTypeOfResults as $index => $result) {
                        if ($result) {
                            return $possibleTypes[$index];
                        }
                    }

                    return null;
                });
        }

        return null;
    }

    /**
     * @param ObjectType $returnType
     * @param             $fieldNodes
     * @param ResolveInfo $info
     * @param             $path
     * @param             $result
     *
     * @return array
     * @throws ExecutionException
     * @throws InvalidTypeException
     * @throws \Digia\GraphQL\Error\InvariantException
     * @throws \Throwable
     */
    private function completeObjectValue(
        ObjectType $returnType,
        $fieldNodes,
        ResolveInfo $info,
        $path,
        &$result
    ) {

        if (null !== $returnType->getIsTypeOf()) {
            $isTypeOf = $returnType->isTypeOf($result,
                $this->context->getContextValue(), $info);
            //@TODO check for promise?
            if (!$isTypeOf) {
                throw new ExecutionException(
                    sprintf('Expected value of type "%s" but received: %s.',
                        (string)$returnType, toString($result))
                );
            }
        }

        return $this->collectAndExecuteSubFields(
            $returnType,
            $fieldNodes,
            $info,
            $path,
            $result
        );
    }

    /**
     * @param ObjectType $returnType
     * @param             $fieldNodes
     * @param ResolveInfo $info
     * @param             $path
     * @param             $result
     *
     * @return array
     * @throws InvalidTypeException
     * @throws \Digia\GraphQL\Error\ExecutionException
     * @throws \Digia\GraphQL\Error\InvariantException
     * @throws \Throwable
     */
    private function collectAndExecuteSubFields(
        ObjectType $returnType,
        $fieldNodes,
        ResolveInfo $info,
        $path,
        &$result
    ) {
        $subFields = [];
        $visitedFragmentNames = [];

        foreach ($fieldNodes as $fieldNode) {
            /** @var FieldNode $fieldNode */
            if ($fieldNode->getSelectionSet() !== null) {
                $subFields = $this->collectFields(
                    $returnType,
                    $fieldNode->getSelectionSet(),
                    $subFields,
                    $visitedFragmentNames
                );
            }
        }

        if (!empty($subFields)) {
            return $this->executeFields($returnType, $result, $path,
                $subFields);
        }

        return $result;
    }

    /**
     * @param ObjectType $runtimeType
     * @param SelectionSetNode $selectionSet
     * @param                  $fields
     * @param                  $visitedFragmentNames
     *
     * @return mixed
     * @throws InvalidTypeException
     * @throws \Digia\GraphQL\Error\ExecutionException
     * @throws \Digia\GraphQL\Error\InvariantException
     */
    protected function collectFields(
        ObjectType $runtimeType,
        SelectionSetNode $selectionSet,
        &$fields,
        &$visitedFragmentNames
    ) {
        foreach ($selectionSet->getSelections() as $selection) {
            // Check if this Node should be included first
            if (!$this->shouldIncludeNode($selection)) {
                continue;
            }
            // Collect fields
            if ($selection instanceof FieldNode) {
                $fieldName = $this->getFieldNameKey($selection);

                if (!isset($fields[$fieldName])) {
                    $fields[$fieldName] = [];
                }

                $fields[$fieldName][] = $selection;
            } elseif ($selection instanceof InlineFragmentNode) {
                if (!$this->doesFragmentConditionMatch($selection,
                    $runtimeType)) {
                    continue;
                }

                $this->collectFields($runtimeType,
                    $selection->getSelectionSet(), $fields,
                    $visitedFragmentNames);
            } elseif ($selection instanceof FragmentSpreadNode) {
                $fragmentName = $selection->getNameValue();

                if (!empty($visitedFragmentNames[$fragmentName])) {
                    continue;
                }

                $visitedFragmentNames[$fragmentName] = true;
                /** @var FragmentDefinitionNode $fragment */
                $fragment = $this->context->getFragments()[$fragmentName];
                $this->collectFields($runtimeType, $fragment->getSelectionSet(),
                    $fields, $visitedFragmentNames);
            }
        }

        return $fields;
    }

    /**
     * @param $node
     *
     * @return bool
     * @throws InvalidTypeException
     * @throws \Digia\GraphQL\Error\ExecutionException
     * @throws \Digia\GraphQL\Error\InvariantException
     */
    private function shouldIncludeNode(NodeInterface $node): bool
    {

        $contextVariables = $this->context->getVariableValues();

        $skip = coerceDirectiveValues(SkipDirective(), $node,
            $contextVariables);

        if ($skip && $skip['if'] === true) {
            return false;
        }

        $include = coerceDirectiveValues(IncludeDirective(), $node,
            $contextVariables);

        if ($include && $include['if'] === false) {
            return false;
        }

        return true;
    }

    /**
     * @TODO: consider to move this to FieldNode
     *
     * @param FieldNode $node
     *
     * @return string
     */
    private function getFieldNameKey(FieldNode $node): string
    {
        return $node->getAlias() ? $node->getAlias()

The expression return $node->getAlias() ? $node->getAlias()->getValue() : $node->getNameValue() could return the type null which is incompatible with the type-hinted return string. Consider adding an additional type-check to rule them out.

            ->getValue() : $node->getNameValue();
    }

    /**
     * @param FragmentDefinitionNode|InlineFragmentNode $fragment
     * @param ObjectType $type
     *
     * @return bool
     * @throws InvalidTypeException
     */
    private function doesFragmentConditionMatch(
        NodeInterface $fragment,
        ObjectType $type
    ): bool {
        $typeConditionNode = $fragment->getTypeCondition();

The method getTypeCondition() does not exist on Digia\GraphQL\Language\Node\NodeInterface. It seems like you code against a sub-type of Digia\GraphQL\Language\Node\NodeInterface such as Digia\GraphQL\Language\Node\InlineFragmentNode or Digia\GraphQL\Language\Node\FragmentDefinitionNode.

        if (!$typeConditionNode) {
            return true;
        }

        $conditionalType = typeFromAST($this->context->getSchema(),
            $typeConditionNode);

        if ($conditionalType === $type) {
            return true;
        }

        if ($conditionalType instanceof AbstractTypeInterface) {
            return $this->context->getSchema()
                ->isPossibleType($conditionalType, $type);
        }

        return false;
    }

    /**
     * Implements the "Evaluating selection sets" section of the spec for
     * "read" mode.
     *
     * @param ObjectType $objectType
     * @param            $rootValue
     * @param            $path
     * @param            $fields
     *
     * @return array
     * @throws InvalidTypeException
     * @throws \Digia\GraphQL\Error\ExecutionException
     * @throws \Digia\GraphQL\Error\InvariantException
     * @throws \Throwable
     */
    protected function executeFields(
        ObjectType $objectType,
        $rootValue,
        $path,
        $fields
    ): array {
        $finalResults = [];
        $isContainsPromise = false;

        foreach ($fields as $fieldName => $fieldNodes) {
            $fieldPath = $path;
            $fieldPath[] = $fieldName;

            try {
                $result = $this->resolveField($objectType, $rootValue,

Are you sure the assignment to $result is correct as $this->resolveField($objectType, $rootValue, $fieldNodes, $fieldPath) targeting Digia\GraphQL\Execution\ExecutionStrategy::resolveField() seems to always return null.

                    $fieldNodes, $fieldPath);
            } catch (UndefinedException $ex) {
                continue;
            }

            $isContainsPromise = $isContainsPromise || $this->isPromise($result);

            $finalResults[$fieldName] = $result;
        }

        if ($isContainsPromise) {
            $keys = array_keys($finalResults);
            $promise = \React\Promise\all(array_values($finalResults));
            $promise->then(function ($values) use ($keys, &$finalResults) {
                foreach ($values as $i => $value) {
                    $finalResults[$keys[$i]] = $value;
                }
            });
        }

        return $finalResults;
    }

    /**
     * @param                       $runtimeTypeOrName
     * @param AbstractTypeInterface $returnType
     * @param                       $fieldNodes
     * @param ResolveInfo $info
     * @param                       $result
     *
     * @return TypeInterface|ObjectType|null
     * @throws ExecutionException
     */
    private function ensureValidRuntimeType(
        $runtimeTypeOrName,
        AbstractTypeInterface $returnType,
        $fieldNodes,
        ResolveInfo $info,
        &$result
    ) {
        $runtimeType = is_string($runtimeTypeOrName)
            ? $this->context->getSchema()->getType($runtimeTypeOrName)
            : $runtimeTypeOrName;

        $runtimeTypeName = is_string($runtimeType) ?: $runtimeType->getName();

The method getName() does not exist on null.

The method getName() does not exist on Digia\GraphQL\Type\Definition\TypeInterface. It seems like you code against a sub-type of said class. However, the method does not exist in Digia\GraphQL\Type\Definition\AbstractTypeInterface or Digia\GraphQL\Type\Definition\WrappingTypeInterface. Are you sure you never get one of those?

        $returnTypeName = $returnType->getName();

The method getName() does not exist on Digia\GraphQL\Type\Definition\AbstractTypeInterface. Since it exists in all sub-types, consider adding an abstract or default implementation to Digia\GraphQL\Type\Definition\AbstractTypeInterface.

        if (!$runtimeType instanceof ObjectType) {
            $parentTypeName = $info->getParentType()->getName();
            $fieldName = $info->getFieldName();

            throw new ExecutionException(
                "Abstract type {$returnTypeName} must resolve to an Object type at runtime ".
                "for field {$parentTypeName}.{$fieldName} with ".
                'value "'.$result.'", received "{$runtimeTypeName}".'
            );
        }

        if (!$this->context->getSchema()
            ->isPossibleType($returnType, $runtimeType)) {
            throw new ExecutionException(
                "Runtime Object type \"{$runtimeTypeName}\" is not a possible type for \"{$returnTypeName}\"."
            );
        }

        if ($runtimeType !== $this->context->getSchema()
                ->getType($runtimeType->getName())) {
            throw new ExecutionException(
                "Schema must contain unique named types but contains multiple types named \"{$runtimeTypeName}\". ".
                "Make sure that `resolveType` function of abstract type \"{$returnTypeName}\" returns the same ".
                "type instance as referenced anywhere else within the schema."
            );
        }

        return $runtimeType;
    }

    /**
     * @param \Throwable $originalException
     * @param array $nodes
     * @param string|array $path
     *
     * @return GraphQLException
     */
    protected function buildLocatedError(
        \Throwable $originalException,
        array $nodes = [],
        array $path = []
    ): ExecutionException {
        return new ExecutionException(
            $originalException->getMessage(),
            $originalException instanceof GraphQLException ? $originalException->getNodes() : $nodes,
            $originalException instanceof GraphQLException ? $originalException->getSource() : null,
            $originalException instanceof GraphQLException ? $originalException->getPositions() : null,
            $originalException instanceof GraphQLException ? ($originalException->getPath() ?? $path) : $path,
            $originalException
        );
    }
}