/**
* Resolves the field on the given source object. In particular, this
* figures out the value that the field returns by calling its resolve function,
* then calls completeValue to complete promises, serialize scalars, or execute
* the sub-selection-set for objects.
*/
private static function resolveField(ExecutionContext $exeContext, ObjectType $parentType, $source, $fieldASTs)
{
$fieldAST = $fieldASTs[0];
$fieldName = $fieldAST->name->value;
$fieldDef = self::getFieldDef($exeContext->schema, $parentType, $fieldName);
if (!$fieldDef) {
return self::$UNDEFINED;
}
$returnType = $fieldDef->getType();
if (isset($fieldDef->resolve)) {
$resolveFn = $fieldDef->resolve;
} else {
if (isset(self::$defaultResolveFn)) {
$resolveFn = self::$defaultResolveFn;
} else {
$resolveFn = [__CLASS__, 'defaultResolveFn'];
}
}
// Build hash of arguments from the field.arguments AST, using the
// variables scope to fulfill any variable references.
// TODO: find a way to memoize, in case this field is within a List type.
$args = Values::getArgumentValues($fieldDef->args, $fieldAST->arguments, $exeContext->variableValues);
// The resolve function's optional third argument is a collection of
// information about the current execution state.
$info = new ResolveInfo(['fieldName' => $fieldName, 'fieldASTs' => $fieldASTs, 'returnType' => $returnType, 'parentType' => $parentType, 'schema' => $exeContext->schema, 'fragments' => $exeContext->fragments, 'rootValue' => $exeContext->rootValue, 'operation' => $exeContext->operation, 'variableValues' => $exeContext->variableValues]);
// If an error occurs while calling the field `resolve` function, ensure that
// it is wrapped as a GraphQLError with locations. Log this error and return
// null if allowed, otherwise throw the error so the parent field can handle
// it.
try {
$result = call_user_func($resolveFn, $source, $args, $info);
} catch (\Exception $error) {
$reportedError = Error::createLocatedError($error, $fieldASTs);
if ($returnType instanceof NonNull) {
throw $reportedError;
}
$exeContext->addError($reportedError);
return null;
}
return self::completeValueCatchingError($exeContext, $returnType, $fieldASTs, $info, $result);
}
/**
* Given list of parent type values returns corresponding list of field values
*
* In particular, this
* figures out the value that the field returns by calling its `resolve` or `map` function,
* then calls `completeValue` on each value to serialize scalars, or execute the sub-selection-set
* for objects.
*
* @param ExecutionContext $exeContext
* @param ObjectType $parentType
* @param $sourceValueList
* @param $fieldASTs
* @return array
* @throws Error
*/
private static function resolveField(ExecutionContext $exeContext, ObjectType $parentType, $sourceValueList, $fieldASTs, $responseName, &$resolveResult)
{
$fieldAST = $fieldASTs[0];
$uid = self::getUid($fieldAST);
// Get memoized variables if they exist
if (isset(self::$memoized['resolveField'][$uid])) {
$memoized = self::$memoized['resolveField'][$uid];
$fieldDef = $memoized['fieldDef'];
$returnType = $fieldDef->getType();
$args = $memoized['args'];
$info = $memoized['info'];
} else {
$fieldName = $fieldAST->name->value;
$fieldDef = self::getFieldDef($exeContext->schema, $parentType, $fieldName);
if (!$fieldDef) {
return;
}
$returnType = $fieldDef->getType();
// Build hash of arguments from the field.arguments AST, using the
// variables scope to fulfill any variable references.
$args = Values::getArgumentValues($fieldDef->args, $fieldAST->arguments, $exeContext->variableValues);
// The resolve function's optional third argument is a collection of
// information about the current execution state.
$info = new ResolveInfo(['fieldName' => $fieldName, 'fieldASTs' => $fieldASTs, 'returnType' => $returnType, 'parentType' => $parentType, 'schema' => $exeContext->schema, 'fragments' => $exeContext->fragments, 'rootValue' => $exeContext->rootValue, 'operation' => $exeContext->operation, 'variableValues' => $exeContext->variableValues]);
self::$memoized['resolveField'][$uid] = ['fieldDef' => $fieldDef, 'args' => $args, 'info' => $info, 'results' => new \SplObjectStorage()];
}
$mapFn = $fieldDef->mapFn;
// If an error occurs while calling the field `map` or `resolve` function, ensure that
// it is wrapped as a GraphQLError with locations. Log this error and return
// null if allowed, otherwise throw the error so the parent field can handle
// it.
if ($mapFn) {
try {
$mapped = call_user_func($mapFn, $sourceValueList, $args, $info);
Utils::invariant(is_array($mapped) && count($mapped) === count($sourceValueList), "Function `map` of {$parentType}.{$fieldName} is expected to return array " . "with exact same number of items as list being mapped (first argument of `map`)");
} catch (\Exception $error) {
$reportedError = Error::createLocatedError($error, $fieldASTs);
if ($returnType instanceof NonNull) {
throw $reportedError;
}
$exeContext->addError($reportedError);
return null;
}
foreach ($mapped as $index => $value) {
$resolveResult[$index][$responseName] = self::completeValueCatchingError($exeContext, $returnType, $fieldASTs, $info, $value);
}
} else {
if (isset($fieldDef->resolveFn)) {
$resolveFn = $fieldDef->resolveFn;
} else {
if (isset($parentType->resolveFieldFn)) {
$resolveFn = $parentType->resolveFieldFn;
} else {
$resolveFn = self::$defaultResolveFn;
}
}
foreach ($sourceValueList as $index => $value) {
// If FieldAST uid and parent object are both the same as in a previous run,
// use its result instead to prevent unnecessary work. Works for objects only.
$isObject = is_object($value);
if ($isObject && isset(self::$memoized['resolveField'][$uid]['results'][$value])) {
$result = self::$memoized['resolveField'][$uid]['results'][$value];
} else {
try {
$resolved = call_user_func($resolveFn, $value, $args, $info);
} catch (\Exception $error) {
$reportedError = Error::createLocatedError($error, $fieldASTs);
if ($returnType instanceof NonNull) {
throw $reportedError;
}
$exeContext->addError($reportedError);
$resolved = null;
}
$result = self::completeValueCatchingError($exeContext, $returnType, $fieldASTs, $info, $resolved);
if ($isObject) {
self::$memoized['resolveField'][$uid]['results'][$value] = $result;
}
}
$resolveResult[$index][$responseName] = $result;
}
}
}
/**
* Given list of parent type values returns corresponding list of field values
*
* In particular, this
* figures out the value that the field returns by calling its `resolve` or `map` function,
* then calls `completeValue` on each value to serialize scalars, or execute the sub-selection-set
* for objects.
*
* @param ExecutionContext $exeContext
* @param ObjectType $parentType
* @param $sourceValueList
* @param $fieldASTs
* @return array
* @throws Error
*/
private static function resolveField(ExecutionContext $exeContext, ObjectType $parentType, $sourceValueList, $fieldASTs, $responseName, &$resolveResult)
{
$fieldAST = $fieldASTs[0];
$fieldName = $fieldAST->name->value;
$fieldDef = self::getFieldDef($exeContext->schema, $parentType, $fieldName);
if (!$fieldDef) {
return;
}
$returnType = $fieldDef->getType();
// Build hash of arguments from the field.arguments AST, using the
// variables scope to fulfill any variable references.
// TODO: find a way to memoize, in case this field is within a List type.
$args = Values::getArgumentValues($fieldDef->args, $fieldAST->arguments, $exeContext->variableValues);
// The resolve function's optional third argument is a collection of
// information about the current execution state.
$info = new ResolveInfo(['fieldName' => $fieldName, 'fieldASTs' => $fieldASTs, 'returnType' => $returnType, 'parentType' => $parentType, 'schema' => $exeContext->schema, 'fragments' => $exeContext->fragments, 'rootValue' => $exeContext->rootValue, 'operation' => $exeContext->operation, 'variableValues' => $exeContext->variableValues]);
$mapFn = $fieldDef->mapFn;
// If an error occurs while calling the field `map` or `resolve` function, ensure that
// it is wrapped as a GraphQLError with locations. Log this error and return
// null if allowed, otherwise throw the error so the parent field can handle
// it.
if ($mapFn) {
try {
$mapped = call_user_func($mapFn, $sourceValueList, $args, $info);
$validType = is_array($mapped) || $mapped instanceof \Traversable && $mapped instanceof \Countable;
$mappedCount = count($mapped);
$sourceCount = count($sourceValueList);
Utils::invariant($validType && count($mapped) === count($sourceValueList), "Function `map` of {$parentType}.{$fieldName} is expected to return array or " . "countable traversable with exact same number of items as list being mapped. " . "Got '%s' with count '{$mappedCount}' against '{$sourceCount}' expected.", Utils::getVariableType($mapped));
} catch (\Exception $error) {
$reportedError = Error::createLocatedError($error, $fieldASTs);
if ($returnType instanceof NonNull) {
throw $reportedError;
}
$exeContext->addError($reportedError);
return null;
}
foreach ($mapped as $index => $value) {
$resolveResult[$index][$responseName] = self::completeValueCatchingError($exeContext, $returnType, $fieldASTs, $info, $value);
}
} else {
if (isset($fieldDef->resolveFn)) {
$resolveFn = $fieldDef->resolveFn;
} else {
if (isset($parentType->resolveFieldFn)) {
$resolveFn = $parentType->resolveFieldFn;
} else {
$resolveFn = self::$defaultResolveFn;
}
}
foreach ($sourceValueList as $index => $value) {
try {
$resolved = call_user_func($resolveFn, $value, $args, $info);
} catch (\Exception $error) {
$reportedError = Error::createLocatedError($error, $fieldASTs);
if ($returnType instanceof NonNull) {
throw $reportedError;
}
$exeContext->addError($reportedError);
$resolved = null;
}
$resolveResult[$index][$responseName] = self::completeValueCatchingError($exeContext, $returnType, $fieldASTs, $info, $resolved);
}
}
}
/**
* Implements the instructions for completeValue as defined in the
* "Field entries" section of the spec.
*
* If the field type is Non-Null, then this recursively completes the value
* for the inner type. It throws a field error if that completion returns null,
* as per the "Nullability" section of the spec.
*
* If the field type is a List, then this recursively completes the value
* for the inner type on each item in the list.
*
* If the field type is a Scalar or Enum, ensures the completed value is a legal
* value of the type by calling the `serialize` method of GraphQL type
* definition.
*
* Otherwise, the field type expects a sub-selection set, and will complete the
* value by evaluating all sub-selections.
*/
private static function completeValue(ExecutionContext $exeContext, Type $returnType, $fieldASTs, ResolveInfo $info, &$result)
{
if ($result instanceof \Exception) {
throw Error::createLocatedError($result, $fieldASTs);
}
// If field type is NonNull, complete for inner type, and throw field error
// if result is null.
if ($returnType instanceof NonNull) {
$completed = self::completeValue($exeContext, $returnType->getWrappedType(), $fieldASTs, $info, $result);
if ($completed === null) {
throw new Error('Cannot return null for non-nullable type.', $fieldASTs instanceof \ArrayObject ? $fieldASTs->getArrayCopy() : $fieldASTs);
}
return $completed;
}
// If result is null-like, return null.
if (null === $result) {
return null;
}
// If field type is List, complete each item in the list with the inner type
if ($returnType instanceof ListOfType) {
$itemType = $returnType->getWrappedType();
Utils::invariant(is_array($result) || $result instanceof \Traversable, 'User Error: expected iterable, but did not find one.');
$tmp = [];
foreach ($result as $item) {
$tmp[] = self::completeValueCatchingError($exeContext, $itemType, $fieldASTs, $info, $item);
}
return $tmp;
}
// If field type is Scalar or Enum, serialize to a valid value, returning
// null if serialization is not possible.
if ($returnType instanceof ScalarType || $returnType instanceof EnumType) {
Utils::invariant(method_exists($returnType, 'serialize'), 'Missing serialize method on type');
return $returnType->serialize($result);
}
// Field type must be Object, Interface or Union and expect sub-selections.
if ($returnType instanceof ObjectType) {
$runtimeType = $returnType;
} else {
if ($returnType instanceof AbstractType) {
$runtimeType = $returnType->getObjectType($result, $info);
if ($runtimeType && !$returnType->isPossibleType($runtimeType)) {
throw new Error("Runtime Object type \"{$runtimeType}\" is not a possible type for \"{$returnType}\".");
}
} else {
$runtimeType = null;
}
}
if (!$runtimeType) {
return null;
}
// If there is an isTypeOf predicate function, call it with the
// current result. If isTypeOf returns false, then raise an error rather
// than continuing execution.
if (false === $runtimeType->isTypeOf($result, $info)) {
throw new Error("Expected value of type {$runtimeType} but got: " . Utils::getVariableType($result), $fieldASTs);
}
// Collect sub-fields to execute to complete this value.
$subFieldASTs = new \ArrayObject();
$visitedFragmentNames = new \ArrayObject();
for ($i = 0; $i < count($fieldASTs); $i++) {
// Get memoized value if it exists
$uid = self::getFieldUid($fieldASTs[$i], $runtimeType);
if (isset($exeContext->memoized['collectSubFields'][$uid])) {
$subFieldASTs = $exeContext->memoized['collectSubFields'][$uid];
} else {
$selectionSet = $fieldASTs[$i]->selectionSet;
if ($selectionSet) {
$subFieldASTs = self::collectFields($exeContext, $runtimeType, $selectionSet, $subFieldASTs, $visitedFragmentNames);
$exeContext->memoized['collectSubFields'][$uid] = $subFieldASTs;
}
}
}
return self::executeFields($exeContext, $runtimeType, $result, $subFieldASTs);
}