GraphQL\Executor\Executor::resolveField PHP Method

    private static function resolveField(ExecutionContext $exeContext, ObjectType $parentType, $source, $fieldNodes, $path)
    {
        $fieldNode = $fieldNodes[0];
        $fieldName = $fieldNode->name->value;
        $fieldDef = self::getFieldDef($exeContext->schema, $parentType, $fieldName);
        if (!$fieldDef) {
            return self::$UNDEFINED;
        }
        $returnType = $fieldDef->getType();
        // The resolve function's optional third argument is a collection of
        // information about the current execution state.
        $info = new ResolveInfo(['fieldName' => $fieldName, 'fieldNodes' => $fieldNodes, 'returnType' => $returnType, 'parentType' => $parentType, 'path' => $path, 'schema' => $exeContext->schema, 'fragments' => $exeContext->fragments, 'rootValue' => $exeContext->rootValue, 'operation' => $exeContext->operation, 'variableValues' => $exeContext->variableValues]);
        if (isset($fieldDef->resolveFn)) {
            $resolveFn = $fieldDef->resolveFn;
        } else {
            if (isset($parentType->resolveFieldFn)) {
                $resolveFn = $parentType->resolveFieldFn;
            } else {
                $resolveFn = self::$defaultFieldResolver;
            }
        }
        // The resolve function's optional third argument is a context value that
        // is provided to every resolve function within an execution. It is commonly
        // used to represent an authenticated user, or request-specific caches.
        $context = $exeContext->contextValue;
        // Get the resolve function, regardless of if its result is normal
        // or abrupt (error).
        $result = self::resolveOrError($exeContext, $fieldDef, $fieldNode, $resolveFn, $source, $context, $info);
        $result = self::completeValueCatchingError($exeContext, $returnType, $fieldNodes, $info, $path, $result);
        return $result;
    }