[ORM] DataList::relation doesn't work for Group.Memberss

[JorisDebonnet]

Affected Version

silverstripe/recipe-cms 1.1.0
(i.e. framework 4.1.0)

Description

DataList::relation has the following example in the documentation:

// Get members from all Groups:
DataList::Create(\SilverStripe\Security\Group::class)->relation("Members");

But this returns an empty list. From the example's description, that should at least list the Default Administrator (who belongs to the Administrator Group). Is the method broken, or is the example bad?

(I'm trying to fix an issue in symbiote/silverstripe-memberprofiles where I have the same issue of relation("Members") returning an empty list)

Steps to Reproduce

Just try this:

// Get number of Members that are linked to any Group (supposedly):
echo DataList::Create(\SilverStripe\Security\Group::class)->relation("Members")->Count(); // 0
// Get number of Members linked to the Administrator Group:
echo \SilverStripe\Security\Group::get()->byID(2)->Members()->Count(); // 1 or more

[maxime-rainville]

I've confirmed the bug by running @JorisDebonnet's sample code.

I've tried creating a normal user and adding the to the administrator (as opposed to using the default admin) and I still get an empty list.

I think the problems is specific to the Members relation somehow. If I switch to the Roles many-many-relation, I get the expected results.

[maxime-rainville]

Problem is probably related to the Groups::Member() method.

Groups can have SubGroups. So we override the Members relation on groups so that members of child groups get return as well.

[sminnee]

Yeah the relation() method assumes a "normal" relation to some extent, which Members is not.