feat(query): after/before on traversed keys and projections - #403
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Position paging works for related-column order keys and projected records from a decoded tuple. position_of still requires populated relations on instances and selected order keys on Row. Co-authored-by: Cursor <cursoragent@cursor.com>
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## Summary Keyset `after()` / `before()` derived from a query's `order_by`, NULL-placement aware (ADR-0018). A position is the ordered tuple of order-key values; `position_of(row)` reads it; `after(row)` / `before(row)` are sugar. Cursor encoding stays the caller's. - Omitted `nulls=` is `"last"` on every dialect (ADR-0017 — **breaking** vs native PG DESC / SQLite ASC). `"native"` is the explicit escape. - `after(position)` pages forward (exclusive). `None` is legal in every non-PK slot so a pinned-first list can cross into unpinned rows in one query. - `before(position).limit(n)` is the adjacent previous page in declared order; unbounded `before()` is the earlier-row prefix (`first()` and `all()[0]` disagree — documented). - Traversed order keys and projected records page from a tuple (`include()` not required). `position_of` still requires populated relations / selected keys. QueryIR is v14. One Rust expander (`exclusive_stepwise_compare`) owns the compare tree; `before` inverts keys then reuses it. ## Test plan - [x] Slice CI on `feat/position-paging`: #397–#403 (rust, python PR, sqlite+postgres matrix) - [ ] Confirm CI on this PR against `main` - [ ] Smoke: `order_by(pinned_at, "desc").order_by(id).after((None, id))` and `before(pos).limit(n)` Closes #372 Made with [Cursor](https://cursor.com) --------- Co-authored-by: Cursor <cursoragent@cursor.com>
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Description
after/beforenow page when an order key is a related column (order_by(lambda t: t.account.label)) or the query is a projected record. A decoded tuple is enough —include()is not required to page.position_ofon a model instance requires those relations populated (same contract as readingrow.account.label).position_ofon a projectedRowrequires every order key in the projection; otherwise pass a tuple.Changes
_assert_position_order_keys. Root PK must still appear among the order keys (a relatediddoes not count).Nonestays legal in every non-PK slot, including aleft_join'd missing relation.position_of(instance)walks populated__dict__relation hops and errors by path when a hop is unpopulated.ProjectedQuery.position_of(Row)matches order keys by source or output name; missing key tells the caller to pass a tuple.beforeon a path-carrying order key still qualifies throughqualify_column_with_joins(no second expander).Bridge and Schema Impact
src/ferro/_core.pyiupdated (if needed)Python builder/validation only plus a Rust unit pin. QueryIR is unchanged (
ir_versionstays 14). Path-carryingorder_byalready qualified in the walker.Migration / Breaking Changes
Queries that previously raised "traversed order key is not supported yet" now page.
Documentation and Changelog
User-visible
feat— release tooling records the changelog (I-10). Do not hand-editCHANGELOG.md.Related Issues
Test plan
after/beforefrom a tuple (noinclude()),left_join+Nonerelated slot, projected-record paging,position_ofpopulated vs unpopulatedidis not the model PK, expression order keys still fail atorder_by()cargo test --no-default-features --features testing query::(includesbefore_condition_qualifies_path_carrying_order_key)uv run ty check src/ferro/querypytest-postgresqlcannot start locally (pg_ctl initdbfailed). CI will run it.Exit Steps
Made with Cursor