/**
* Resolves the field on the given source object. In particular, this
* figures out the object that the field returns using the resolve function,
* then calls completeField to coerce scalars or execute the sub
* selection set for objects.
*/
private static function resolveFieldOrError(ExecutionContext $exeContext, ObjectType $parentType, $source, $fieldASTs, FieldDefinition $fieldDef)
{
$fieldAST = $fieldASTs[0];
$fieldType = $fieldDef->getType();
$resolveFn = $fieldDef->resolve ?: [__CLASS__, 'defaultResolveFn'];
// Build a JS object 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 Array type.
$args = Values::getArgumentValues($fieldDef->args, $fieldAST->arguments, $exeContext->variables);
try {
$result = call_user_func($resolveFn, $source, $args, $exeContext->root, $fieldAST, $fieldType, $parentType, $exeContext->schema);
} catch (\Exception $error) {
throw new Error($error->getMessage(), [$fieldAST], $error->getTrace());
}
return self::completeField($exeContext, $fieldType, $fieldASTs, $result);
}
