ListThread service: add is_mine parameter

[GeoffreyHuck]

Issue #888

This PR handles the is_mine parameter for the listThread service.

Some rights between this and the getThread have been factorized into WhereUserCanHelp:

	// the following rules all matches:
	// the current-user is descendant of the thread helper_group
	// the thread is either open (=waiting_for_participant or =waiting_for_trainer), or closed for less than 2 weeks
	// the current-user has validated the item

The function NewThreadStore has been added because when we use a function defined on *DB, we end up being unable to use functions defined on *ThreadStore anymore, because we get a *DB in return. The reason relates to types: A *ThreadStore is a *DataStore is a *DB, but a *DB is not a *ThreadStore.

I'm not sure what's the best thing to do here, maybe there exists a pattern that would handle this case smoothly in go. The code seems to struggle with this everywhere, where the pattern used is:

func (s *ItemAncestorStore) DescendantsOf(ancestorID int64) *ItemItemStore {
	return &ItemItemStore{NewDataStoreWithTable(
		s.Where("items_ancestors.ancestor_item_id = ?", ancestorID), s.tableName,
	)}
}

At other times, it returns a *DB instead of a DataStore to avoid this issue. But then we lose consistence with some methods defined on a specific store which returns a specific *DataStore (eg. *ThreadStore, *GroupStore, ...), and others who return a *DB. It would be nice to decide which pattern to use for uniformization, and if possible for simplicity.

Note: I would have liked to add a "default" to the switch statement in list_threads to guarantee the correctness of the parameters. But the parameters are checked before in a function, and it made the code within the default unreachable, so it didn't pass the code coverage tests.

[codecov]

Codecov Report

Merging #943 (07bf7f1) into master (26ffdc1) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #943   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          225       225           
  Lines        13466     13503   +37     
=========================================
+ Hits         13466     13503   +37     

Impacted Files	Coverage Δ
app/api/threads/list_threads.go	100.00% <100.00%> (ø)
app/database/thread_store.go	100.00% <100.00%> (ø)

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[smadbe]

Missing ref to the issue it is fixing.

[GeoffreyHuck]

Missing ref to the issue it is fixing.

It's not finished yet, still requires the parameter item_id and the sorting/filter/pagination.

[smadbe]

looks good

[smadbe]

I don't see this rule used anywhere

[GeoffreyHuck]

fixed, indeed I removed it