StandardRelatedDataService not working for complex relations

[sb-relaxt-at]

Affected Version

Any version including StandardRelatedDataService (Silverstripe 4 and 5).

Description

There are multiple cases in which the StandardRelatedDataService does not work (Undefined index) or return wrong results. I do understand that the DataService is marked for internal use and might be not intended for use with other DataObjects than Files. Nevertheless these issues also occur if Files are used in complex relationships.

Case 1

There is no support for polymorphic relations besides the Parent relation. If polymorphic relations are involved there will be no filtering by class, resulting in wrong related data returned.

silverstripe-framework/src/ORM/RelatedData/StandardRelatedDataService.php

Line 120 in 26c8c0f

if ($componentIDField === 'ParentID' && $record->ParentClass) {

silverstripe-framework/src/ORM/RelatedData/StandardRelatedDataService.php

Line 231 in 26c8c0f

$selectFields[] = 'ParentClass';

silverstripe-framework/src/ORM/RelatedData/StandardRelatedDataService.php

Line 318 in 26c8c0f

$where .= sprintf(' AND "ParentClass" = %s', $this->prepareClassNameLiteral(get_class($record)));

silverstripe-framework/src/ORM/RelatedData/StandardRelatedDataService.php

Line 371 in 26c8c0f

if (count(array_keys($row ?? [])) === 2 && isset($row['ParentClass']) && isset($row['ParentID'])) {

Case 2

Given the the following DataObject structure for a Many-many-through Relation between X and Y by class B:

A:
  has_one:
    x: X
B: #extends A
  has_one:
    y: Y

The service won't be able to find the configuration for x as it uses the uninherited config of B which does not include the relation to X, resulting in an Undefined index see:

silverstripe-framework/src/ORM/RelatedData/StandardRelatedDataService.php

Line 417 in 26c8c0f

return $this->config[$lowercaseThroughClass]['has_one'][$toComponent];

Edit: Fixed a wrong relation in the example.

[emteknetnz]

Case 1 will be fixed in 5.2.0 with this PR - #11107

[sb-relaxt-at]

@emteknetnz I am not sure that your PR addresses all references to Parent in StandardRelatedDataService, I suppose there are at least four of them.