[2013-02-13] ManyManyList->removeAll() not working with JOINs

[silverstripe-issues]

created by: @chillu (ischommer)
created at: 2013-02-13
original ticket: http://open.silverstripe.org/ticket/8258

---

ManyManyList causes a single DELETE query, as opposed to DataList which does one DELETE query per item. This means the single DELETE query needs to replicate all selection criteria if ot was "converted" from a SELECT query before.

Emulating joins in deletes is possible, but its going to be gricky to satisfy all potential query permutations. My recommendation is to change to single-row DELETE queries which work on the results from executing the SELECT queries.

For context, this problem was discovered with "Group" queries breaking on usage of both subsites and advancedworkflow

[tractorcow]

If this exists in 3.1 it needs to be fixed there also.

[dhensby]

I don't get it, how's the problem replicated and how does it manifest itself?

[tractorcow]

It sounds like the problem is limited to Member_Groupset. maybe just limit the suggested fix to that? (copy DataList::removeAll() to Member_Groupset).

[kinglozzer]

Related to #3948?

[tractorcow]

ok, I'm closing this in favour of #3948 which more precisely targets the issue (even though it's newer).