Opened 2 years ago

Closed 6 months ago

#22936 closed Cleanup/optimization (fixed)

Get rid of field.get_db_prep_lookup()

Reported by: Anssi Kääriäinen Owned by: nobody
Component: Database layer (models, ORM) Version: master
Severity: Normal Keywords:
Cc: Triage Stage: Ready for checkin
Has patch: yes Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description (last modified by Tim Graham)

The Field.get_db_prep_lookup() method is used to do preparation of a plain Python value for given lookup. Looking at the coding of get_db_prep_lookup() the get_db_prep_lookup() is doing work that belongs into the lookup itself.

The same goes also for get_prep_lookup(). It seems that get_prep_lookup() is either doing something that should actually be done in get_prep_value(), or something that belongs into lookups.

If a custom field needs to do different kind of preparation for some lookups (something that can't be done in get_[db_]prep_value(), it can always provide a lookup subclass that does the right thing for that field type. An example is IntegerField and 'lt' and 'gte' lookups. Providing custom subclasses might be laborious to do if there are a lot of different lookup types that need custom preparation. For that reason a hook for custom fields could still be useful.

Even if we want to leave get_db_prep_lookup and get_prep_lookup hooks for custom fields, the base coding belongs into the lookups themselves. Currently the fields are doing work that clearly belongs to the lookup itself.

Change History (9)

comment:1 Changed 2 years ago by Tim Graham

Description: modified (diff)
Triage Stage: UnreviewedAccepted

comment:2 Changed 7 months ago by Tim Graham

Description: modified (diff)

As suggested in the ticket description, I did the small step of moving IntegerField.get_prep_lookup() to lookup subclasses: PR.

comment:3 Changed 7 months ago by Tim Graham <timograham@…>

In 1c30a647:

Refs #22936 -- Moved IntegerField.get_prep_lookup() logic to lookups.

comment:4 Changed 6 months ago by Claude Paroz

This PR removes the get_prep_lookup method.

comment:5 Changed 6 months ago by Tim Graham <timograham@…>

In 1ba0b22:

Refs #22936 -- Removed unused code in Field.get_db_prep_lookup().

comment:6 Changed 6 months ago by Tim Graham <timograham@…>

In eab5df1:

Refs #22936 -- Moved more of Field.get_db_prep_lookup() to lookups.

comment:7 Changed 6 months ago by Tim Graham

Has patch: set

I submitted a PR to Claude's PR in comment:4 which completes the ticket.

comment:8 Changed 6 months ago by Tim Graham

Triage Stage: AcceptedReady for checkin

comment:9 Changed 6 months ago by Claude Paroz <claude@…>

Resolution: fixed
Status: newclosed

In 388bb5b:

Fixed #22936 -- Obsoleted Field.get_prep_lookup()/get_db_prep_lookup()

Thanks Tim Graham for completing the initial patch.

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