Decouple Filter Classes

[borhanst]

Parent

#16 — Database Backend Abstraction for Multi-ORM Support

What to build

Update Filter ABC and all subclasses in filters/base.py to accept QueryBackend instead of raw SQLAlchemy query objects.

Changes:

• Filter.apply(query, value) — query parameter type changes from Any (SQLAlchemy select) to QueryBackend
• Remove query.column_descriptions[0]["entity"] pattern — filters should receive the model reference separately or via the query adapter
• TextFilter, BooleanFilter, RelationFilter, EnumFilter: use query.where(col == value) via query adapter
• NumericFilter, DateRangeFilter, DatetimeRangeFilter: use query.where(col >= val) via query adapter
• AutocompleteFilter: use query.where(col == value) via query adapter
• get_choices(session) — session parameter type changes to SessionBackend

Update DefaultQueryProvider._get_filter_choices() to pass SessionBackend to filter choices.

Acceptance criteria

• Filter.apply() accepts QueryBackend as first parameter
• All 7 filter subclasses updated to use query adapter methods
• get_choices() accepts SessionBackend
• Zero direct SQLAlchemy imports in filters/base.py
• All existing filter tests pass

Blocked by

#25 (Query Adapter)

[borhanst]

Implemented in #33