Recent Odoo versions require modern postgres (e.g. use of jsonb), the
`NULLS {FIRST | LAST}` clause was added in 8.3 so should be well
supported.
While Odoo's use of nulls is not always consistent, the NULLS ordering
clauses can be quite useful especially when sorting `DESC`: `NULLS
FIRST` and `NULLS LAST` are literal positions so they put nulls at
that location regardless of sort order whereas the default Postgres
ordering is to consider nulls larger than every other value so they
appear first when sorting DESC, which is often undesirable (putting
nulls first when sorting ASC can also be useful to fill records).
Update `_generate_order_by_inner` to correctly process `NULLS` clauses:
- Use `regex_order` to ensure we parse orderings correctly and
consistently, also update `regex_order` to use named groups to make
the relevant bits clearer (and VERBOSE for readability).
- Given `a_id DESC` and `_fields[a_id].relation._order = 'xxx NULLS
LAST'`, reversing the clause should order by `xxx DESC NULLS FIRST`
to correctly flip the original as `NULLS` clauses are not relative
to the sorting order (they put the `NULL`-valued records at the
specified location regardless). Therefore apply `reverse_direction`
to `NULLS`.
- Manually expand `NULLS` clauses on m2o fields: propagating the
clause through the join would yield unexpected and illogical results
when mixing NULL m2o fields and non-NULL m2o fields with NULL
`_order` fields (as they would get mixed rather than clearly layered
/ separated).
However because SQL booleans are ordered the usual way (`true >
false`) the `NULLS` clause is fundamentally equivalent to sorting on
the field being NULL (if `NULLS LAST`) or not (if `NULLS FIRST`). So
we can prepend the expanded m2o's ordering with such a clause to get
the correct behavior.
Replaces #116464
Supersedes #116664closesodoo/odoo#117439
Signed-off-by: Raphael Collet <rco@odoo.com>
Co-authored-by: Petar Najman <petar.najman@modoolar.com>
Petar Najman
6a89f5b4f9