feat: unified paginate() endpoint with typed pagination responses

docs_src/examples/pagination_search/routes.py

@@ -2,8 +2,12 @@ from typing import Annotated
 
 from fastapi import APIRouter, Depends, Query
 
-from fastapi_toolsets.crud import OrderByClause
+from fastapi_toolsets.crud import OrderByClause, PaginationType
-from fastapi_toolsets.schemas import PaginatedResponse
+from fastapi_toolsets.schemas import (
+    CursorPaginatedResponse,
+    OffsetPaginatedResponse,
+    PaginatedResponse,
+)
 
 from .crud import ArticleCrud
 from .db import SessionDep
@@ -24,7 +28,7 @@ async def list_articles_offset(
     page: int = Query(1, ge=1),
     items_per_page: int = Query(20, ge=1, le=100),
     search: str | None = None,
-) -> PaginatedResponse[ArticleRead]:
+) -> OffsetPaginatedResponse[ArticleRead]:
     return await ArticleCrud.offset_paginate(
         session=session,
         page=page,
@@ -47,7 +51,7 @@ async def list_articles_cursor(
     cursor: str | None = None,
     items_per_page: int = Query(20, ge=1, le=100),
     search: str | None = None,
-) -> PaginatedResponse[ArticleRead]:
+) -> CursorPaginatedResponse[ArticleRead]:
     return await ArticleCrud.cursor_paginate(
         session=session,
         cursor=cursor,
@@ -57,3 +61,30 @@ async def list_articles_cursor(
         order_by=order_by,
         schema=ArticleRead,
     )
+
+
+@router.get("/")
+async def list_articles(
+    session: SessionDep,
+    filter_by: Annotated[dict[str, list[str]], Depends(ArticleCrud.filter_params())],
+    order_by: Annotated[
+        OrderByClause | None,
+        Depends(ArticleCrud.order_params(default_field=Article.created_at)),
+    ],
+    pagination_type: PaginationType = PaginationType.OFFSET,
+    page: int = Query(1, ge=1),
+    cursor: str | None = None,
+    items_per_page: int = Query(20, ge=1, le=100),
+    search: str | None = None,
+) -> PaginatedResponse[ArticleRead]:
+    return await ArticleCrud.paginate(
+        session,
+        pagination_type=pagination_type,
+        page=page,
+        cursor=cursor,
+        items_per_page=items_per_page,
+        search=search,
+        filter_by=filter_by or None,
+        order_by=order_by,
+        schema=ArticleRead,
+    )

src/fastapi_toolsets/crud/__init__.py

@@ -1,6 +1,7 @@
 """Generic async CRUD operations for SQLAlchemy models."""
 
 from ..exceptions import InvalidFacetFilterError, NoSearchableFieldsError
+from ..schemas import PaginationType
 from ..types import (
     FacetFieldType,
     JoinType,
@@ -8,10 +9,11 @@ from ..types import (
     OrderByClause,
     SearchFieldType,
 )
-from .factory import CrudFactory
+from .factory import AsyncCrud, CrudFactory
 from .search import SearchConfig, get_searchable_fields
 
 __all__ = [
+    "AsyncCrud",
     "CrudFactory",
     "FacetFieldType",
     "get_searchable_fields",
@@ -20,6 +22,7 @@ __all__ = [
     "M2MFieldType",
     "NoSearchableFieldsError",
     "OrderByClause",
+    "PaginationType",
     "SearchConfig",
     "SearchFieldType",
 ]

src/fastapi_toolsets/crud/factory.py

@@ -23,7 +23,14 @@ from sqlalchemy.sql.roles import WhereHavingRole
 
 from ..db import get_transaction
 from ..exceptions import InvalidOrderFieldError, NotFoundError
-from ..schemas import CursorPagination, OffsetPagination, PaginatedResponse, Response
+from ..schemas import (
+    CursorPaginatedResponse,
+    CursorPagination,
+    OffsetPaginatedResponse,
+    OffsetPagination,
+    PaginationType,
+    Response,
+)
 from ..types import (
     FacetFieldType,
     JoinType,
@@ -889,7 +896,7 @@ class AsyncCrud(Generic[ModelType]):
         facet_fields: Sequence[FacetFieldType] | None = None,
         filter_by: dict[str, Any] | BaseModel | None = None,
         schema: type[BaseModel],
-    ) -> PaginatedResponse[Any]:
+    ) -> OffsetPaginatedResponse[Any]:
         """Get paginated results using offset-based pagination.
 
         Args:
@@ -971,7 +978,7 @@ class AsyncCrud(Generic[ModelType]):
             session, facet_fields, filters, search_joins
         )
 
-        return PaginatedResponse(
+        return OffsetPaginatedResponse(
             data=items,
             pagination=OffsetPagination(
                 total_count=total_count,
@@ -999,7 +1006,7 @@ class AsyncCrud(Generic[ModelType]):
         facet_fields: Sequence[FacetFieldType] | None = None,
         filter_by: dict[str, Any] | BaseModel | None = None,
         schema: type[BaseModel],
-    ) -> PaginatedResponse[Any]:
+    ) -> CursorPaginatedResponse[Any]:
         """Get paginated results using cursor-based pagination.
 
         Args:
@@ -1113,7 +1120,7 @@ class AsyncCrud(Generic[ModelType]):
             session, facet_fields, filters, search_joins
         )
 
-        return PaginatedResponse(
+        return CursorPaginatedResponse(
             data=items,
             pagination=CursorPagination(
                 next_cursor=next_cursor,
@@ -1124,6 +1131,136 @@ class AsyncCrud(Generic[ModelType]):
             filter_attributes=filter_attributes,
         )
 
+    @overload
+    @classmethod
+    async def paginate(  # pragma: no cover
+        cls: type[Self],
+        session: AsyncSession,
+        *,
+        pagination_type: Literal[PaginationType.OFFSET],
+        filters: list[Any] | None = ...,
+        joins: JoinType | None = ...,
+        outer_join: bool = ...,
+        load_options: Sequence[ExecutableOption] | None = ...,
+        order_by: OrderByClause | None = ...,
+        page: int = ...,
+        cursor: str | None = ...,
+        items_per_page: int = ...,
+        search: str | SearchConfig | None = ...,
+        search_fields: Sequence[SearchFieldType] | None = ...,
+        facet_fields: Sequence[FacetFieldType] | None = ...,
+        filter_by: dict[str, Any] | BaseModel | None = ...,
+        schema: type[BaseModel],
+    ) -> OffsetPaginatedResponse[Any]: ...
+
+    @overload
+    @classmethod
+    async def paginate(  # pragma: no cover
+        cls: type[Self],
+        session: AsyncSession,
+        *,
+        pagination_type: Literal[PaginationType.CURSOR],
+        filters: list[Any] | None = ...,
+        joins: JoinType | None = ...,
+        outer_join: bool = ...,
+        load_options: Sequence[ExecutableOption] | None = ...,
+        order_by: OrderByClause | None = ...,
+        page: int = ...,
+        cursor: str | None = ...,
+        items_per_page: int = ...,
+        search: str | SearchConfig | None = ...,
+        search_fields: Sequence[SearchFieldType] | None = ...,
+        facet_fields: Sequence[FacetFieldType] | None = ...,
+        filter_by: dict[str, Any] | BaseModel | None = ...,
+        schema: type[BaseModel],
+    ) -> CursorPaginatedResponse[Any]: ...
+
+    @classmethod
+    async def paginate(
+        cls: type[Self],
+        session: AsyncSession,
+        *,
+        pagination_type: PaginationType = PaginationType.OFFSET,
+        filters: list[Any] | None = None,
+        joins: JoinType | None = None,
+        outer_join: bool = False,
+        load_options: Sequence[ExecutableOption] | None = None,
+        order_by: OrderByClause | None = None,
+        page: int = 1,
+        cursor: str | None = None,
+        items_per_page: int = 20,
+        search: str | SearchConfig | None = None,
+        search_fields: Sequence[SearchFieldType] | None = None,
+        facet_fields: Sequence[FacetFieldType] | None = None,
+        filter_by: dict[str, Any] | BaseModel | None = None,
+        schema: type[BaseModel],
+    ) -> OffsetPaginatedResponse[Any] | CursorPaginatedResponse[Any]:
+        """Get paginated results using either offset or cursor pagination.
+
+        Args:
+            session: DB async session.
+            pagination_type: Pagination strategy.  Defaults to
+                ``PaginationType.OFFSET``.
+            filters: List of SQLAlchemy filter conditions.
+            joins: List of ``(model, condition)`` tuples for joining related
+                tables.
+            outer_join: Use LEFT OUTER JOIN instead of INNER JOIN.
+            load_options: SQLAlchemy loader options.  Falls back to
+                ``default_load_options`` when not provided.
+            order_by: Column or expression to order results by.
+            page: Page number (1-indexed).  Only used when
+                ``pagination_type`` is ``OFFSET``.
+            cursor: Cursor token from a previous
+                :class:`.CursorPaginatedResponse`.  Only used when
+                ``pagination_type`` is ``CURSOR``.
+            items_per_page: Number of items per page (default 20).
+            search: Search query string or :class:`.SearchConfig` object.
+            search_fields: Fields to search in (overrides class default).
+            facet_fields: Columns to compute distinct values for (overrides
+                class default).
+            filter_by: Dict of ``{column_key: value}`` to filter by declared
+                facet fields.  Keys must match the ``column.key`` of a facet
+                field.  Scalar → equality, list → IN clause.  Raises
+                :exc:`.InvalidFacetFilterError` for unknown keys.
+            schema: Pydantic schema to serialize each item into.
+
+        Returns:
+            :class:`.OffsetPaginatedResponse` when ``pagination_type`` is
+            ``OFFSET``, :class:`.CursorPaginatedResponse` when it is
+            ``CURSOR``.
+        """
+        if pagination_type is PaginationType.CURSOR:
+            return await cls.cursor_paginate(
+                session,
+                cursor=cursor,
+                filters=filters,
+                joins=joins,
+                outer_join=outer_join,
+                load_options=load_options,
+                order_by=order_by,
+                items_per_page=items_per_page,
+                search=search,
+                search_fields=search_fields,
+                facet_fields=facet_fields,
+                filter_by=filter_by,
+                schema=schema,
+            )
+        return await cls.offset_paginate(
+            session,
+            filters=filters,
+            joins=joins,
+            outer_join=outer_join,
+            load_options=load_options,
+            order_by=order_by,
+            page=page,
+            items_per_page=items_per_page,
+            search=search,
+            search_fields=search_fields,
+            facet_fields=facet_fields,
+            filter_by=filter_by,
+            schema=schema,
+        )
+
 
 def CrudFactory(
     model: type[ModelType],

src/fastapi_toolsets/schemas.py

@@ -1,7 +1,7 @@
 """Base Pydantic schemas for API responses."""
 
 from enum import Enum
-from typing import Any, ClassVar, Generic
+from typing import Any, ClassVar, Generic, Literal
 
 from pydantic import BaseModel, ConfigDict
 
@@ -10,9 +10,12 @@ from .types import DataT
 __all__ = [
     "ApiError",
     "CursorPagination",
+    "CursorPaginatedResponse",
     "ErrorResponse",
     "OffsetPagination",
+    "OffsetPaginatedResponse",
     "PaginatedResponse",
+    "PaginationType",
     "PydanticBase",
     "Response",
     "ResponseStatus",
@@ -123,9 +126,48 @@ class CursorPagination(PydanticBase):
     has_more: bool
 
 
+class PaginationType(str, Enum):
+    """Pagination strategy selector for :meth:`.AsyncCrud.paginate`."""
+
+    OFFSET = "offset"
+    CURSOR = "cursor"
+
+
 class PaginatedResponse(BaseResponse, Generic[DataT]):
-    """Paginated API response for list endpoints."""
+    """Paginated API response for list endpoints.
+
+    Base class and return type for endpoints that support both pagination
+    strategies.  Use :class:`OffsetPaginatedResponse` or
+    :class:`CursorPaginatedResponse` when the strategy is fixed;  use
+    ``PaginatedResponse`` as the return annotation for unified endpoints that
+    dispatch via :meth:`~fastapi_toolsets.crud.factory.AsyncCrud.paginate`.
+    """
 
     data: list[DataT]
     pagination: OffsetPagination | CursorPagination
+    pagination_type: PaginationType | None = None
     filter_attributes: dict[str, list[Any]] | None = None
+
+
+class OffsetPaginatedResponse(PaginatedResponse[DataT]):
+    """Paginated response with typed offset-based pagination metadata.
+
+    The ``pagination_type`` field is always ``"offset"`` and acts as a
+    discriminator, allowing frontend clients to narrow the union type returned
+    by a unified ``paginate()`` endpoint.
+    """
+
+    pagination: OffsetPagination
+    pagination_type: Literal[PaginationType.OFFSET] = PaginationType.OFFSET
+
+
+class CursorPaginatedResponse(PaginatedResponse[DataT]):
+    """Paginated response with typed cursor-based pagination metadata.
+
+    The ``pagination_type`` field is always ``"cursor"`` and acts as a
+    discriminator, allowing frontend clients to narrow the union type returned
+    by a unified ``paginate()`` endpoint.
+    """
+
+    pagination: CursorPagination
+    pagination_type: Literal[PaginationType.CURSOR] = PaginationType.CURSOR

tests/test_example_pagination_search.py

@@ -393,3 +393,105 @@ class TestCursorSorting:
         body = resp.json()
         assert body["error_code"] == "SORT-422"
         assert body["status"] == "FAIL"
+
+
+class TestPaginateUnified:
+    """Tests for the unified GET /articles/ endpoint using paginate()."""
+
+    @pytest.mark.anyio
+    async def test_defaults_to_offset_pagination(
+        self, client: AsyncClient, ex_db_session
+    ):
+        """Without pagination_type, defaults to offset pagination."""
+        await seed(ex_db_session)
+
+        resp = await client.get("/articles/")
+
+        assert resp.status_code == 200
+        body = resp.json()
+        assert body["pagination_type"] == "offset"
+        assert "total_count" in body["pagination"]
+        assert body["pagination"]["total_count"] == 3
+
+    @pytest.mark.anyio
+    async def test_explicit_offset_pagination(self, client: AsyncClient, ex_db_session):
+        """pagination_type=offset returns OffsetPagination metadata."""
+        await seed(ex_db_session)
+
+        resp = await client.get(
+            "/articles/?pagination_type=offset&page=1&items_per_page=2"
+        )
+
+        assert resp.status_code == 200
+        body = resp.json()
+        assert body["pagination_type"] == "offset"
+        assert body["pagination"]["total_count"] == 3
+        assert body["pagination"]["page"] == 1
+        assert body["pagination"]["has_more"] is True
+        assert len(body["data"]) == 2
+
+    @pytest.mark.anyio
+    async def test_cursor_pagination_type(self, client: AsyncClient, ex_db_session):
+        """pagination_type=cursor returns CursorPagination metadata."""
+        await seed(ex_db_session)
+
+        resp = await client.get("/articles/?pagination_type=cursor&items_per_page=2")
+
+        assert resp.status_code == 200
+        body = resp.json()
+        assert body["pagination_type"] == "cursor"
+        assert "next_cursor" in body["pagination"]
+        assert "total_count" not in body["pagination"]
+        assert body["pagination"]["has_more"] is True
+        assert len(body["data"]) == 2
+
+    @pytest.mark.anyio
+    async def test_cursor_pagination_navigate_pages(
+        self, client: AsyncClient, ex_db_session
+    ):
+        """Cursor from first page can be used to fetch the next page."""
+        await seed(ex_db_session)
+
+        first = await client.get("/articles/?pagination_type=cursor&items_per_page=2")
+        assert first.status_code == 200
+        first_body = first.json()
+        next_cursor = first_body["pagination"]["next_cursor"]
+        assert next_cursor is not None
+
+        second = await client.get(
+            f"/articles/?pagination_type=cursor&items_per_page=2&cursor={next_cursor}"
+        )
+        assert second.status_code == 200
+        second_body = second.json()
+        assert second_body["pagination_type"] == "cursor"
+        assert second_body["pagination"]["has_more"] is False
+        assert len(second_body["data"]) == 1
+
+    @pytest.mark.anyio
+    async def test_cursor_pagination_with_search(
+        self, client: AsyncClient, ex_db_session
+    ):
+        """paginate() with cursor type respects search parameter."""
+        await seed(ex_db_session)
+
+        resp = await client.get("/articles/?pagination_type=cursor&search=fastapi")
+
+        assert resp.status_code == 200
+        body = resp.json()
+        assert body["pagination_type"] == "cursor"
+        assert len(body["data"]) == 1
+        assert body["data"][0]["title"] == "FastAPI tips"
+
+    @pytest.mark.anyio
+    async def test_offset_pagination_with_filter(
+        self, client: AsyncClient, ex_db_session
+    ):
+        """paginate() with offset type respects filter_by parameter."""
+        await seed(ex_db_session)
+
+        resp = await client.get("/articles/?pagination_type=offset&status=published")
+
+        assert resp.status_code == 200
+        body = resp.json()
+        assert body["pagination_type"] == "offset"
+        assert body["pagination"]["total_count"] == 2

tests/test_schemas.py

@@ -6,9 +6,12 @@ from pydantic import ValidationError
 from fastapi_toolsets.schemas import (
     ApiError,
     CursorPagination,
+    CursorPaginatedResponse,
     ErrorResponse,
     OffsetPagination,
+    OffsetPaginatedResponse,
     PaginatedResponse,
+    PaginationType,
     Response,
     ResponseStatus,
 )
@@ -312,11 +315,6 @@ class TestPaginatedResponse:
 
     def test_generic_type_hint(self):
         """PaginatedResponse supports generic type hints."""
-
-        class UserOut:
-            id: int
-            name: str
-
         pagination = OffsetPagination(
             total_count=1,
             items_per_page=10,
@@ -371,6 +369,191 @@ class TestPaginatedResponse:
         assert isinstance(response.pagination, CursorPagination)
 
 
+class TestPaginationType:
+    """Tests for PaginationType enum."""
+
+    def test_offset_value(self):
+        """OFFSET has string value 'offset'."""
+        assert PaginationType.OFFSET == "offset"
+        assert PaginationType.OFFSET.value == "offset"
+
+    def test_cursor_value(self):
+        """CURSOR has string value 'cursor'."""
+        assert PaginationType.CURSOR == "cursor"
+        assert PaginationType.CURSOR.value == "cursor"
+
+    def test_is_string_enum(self):
+        """PaginationType is a string enum."""
+        assert isinstance(PaginationType.OFFSET, str)
+        assert isinstance(PaginationType.CURSOR, str)
+
+    def test_members(self):
+        """PaginationType has exactly two members."""
+        assert set(PaginationType) == {PaginationType.OFFSET, PaginationType.CURSOR}
+
+
+class TestOffsetPaginatedResponse:
+    """Tests for OffsetPaginatedResponse schema."""
+
+    def test_pagination_type_is_offset(self):
+        """pagination_type is always PaginationType.OFFSET."""
+        response = OffsetPaginatedResponse(
+            data=[],
+            pagination=OffsetPagination(
+                total_count=0, items_per_page=10, page=1, has_more=False
+            ),
+        )
+        assert response.pagination_type is PaginationType.OFFSET
+
+    def test_pagination_type_serializes_to_string(self):
+        """pagination_type serializes to 'offset' in JSON mode."""
+        response = OffsetPaginatedResponse(
+            data=[],
+            pagination=OffsetPagination(
+                total_count=0, items_per_page=10, page=1, has_more=False
+            ),
+        )
+        assert response.model_dump(mode="json")["pagination_type"] == "offset"
+
+    def test_pagination_field_is_typed(self):
+        """pagination field is OffsetPagination, not the union."""
+        response = OffsetPaginatedResponse(
+            data=[{"id": 1}],
+            pagination=OffsetPagination(
+                total_count=10, items_per_page=5, page=2, has_more=True
+            ),
+        )
+        assert isinstance(response.pagination, OffsetPagination)
+        assert response.pagination.total_count == 10
+        assert response.pagination.page == 2
+
+    def test_is_subclass_of_paginated_response(self):
+        """OffsetPaginatedResponse IS a PaginatedResponse."""
+        response = OffsetPaginatedResponse(
+            data=[],
+            pagination=OffsetPagination(
+                total_count=0, items_per_page=10, page=1, has_more=False
+            ),
+        )
+        assert isinstance(response, PaginatedResponse)
+
+    def test_pagination_type_default_cannot_be_overridden_to_cursor(self):
+        """pagination_type rejects values other than OFFSET."""
+        with pytest.raises(ValidationError):
+            OffsetPaginatedResponse(
+                data=[],
+                pagination=OffsetPagination(
+                    total_count=0, items_per_page=10, page=1, has_more=False
+                ),
+                pagination_type=PaginationType.CURSOR,  # type: ignore[arg-type]
+            )
+
+    def test_filter_attributes_defaults_to_none(self):
+        """filter_attributes defaults to None."""
+        response = OffsetPaginatedResponse(
+            data=[],
+            pagination=OffsetPagination(
+                total_count=0, items_per_page=10, page=1, has_more=False
+            ),
+        )
+        assert response.filter_attributes is None
+
+    def test_full_serialization(self):
+        """Full JSON serialization includes all expected fields."""
+        response = OffsetPaginatedResponse(
+            data=[{"id": 1}],
+            pagination=OffsetPagination(
+                total_count=1, items_per_page=10, page=1, has_more=False
+            ),
+            filter_attributes={"status": ["active"]},
+        )
+        data = response.model_dump(mode="json")
+
+        assert data["pagination_type"] == "offset"
+        assert data["status"] == "SUCCESS"
+        assert data["data"] == [{"id": 1}]
+        assert data["pagination"]["total_count"] == 1
+        assert data["filter_attributes"] == {"status": ["active"]}
+
+
+class TestCursorPaginatedResponse:
+    """Tests for CursorPaginatedResponse schema."""
+
+    def test_pagination_type_is_cursor(self):
+        """pagination_type is always PaginationType.CURSOR."""
+        response = CursorPaginatedResponse(
+            data=[],
+            pagination=CursorPagination(
+                next_cursor=None, items_per_page=10, has_more=False
+            ),
+        )
+        assert response.pagination_type is PaginationType.CURSOR
+
+    def test_pagination_type_serializes_to_string(self):
+        """pagination_type serializes to 'cursor' in JSON mode."""
+        response = CursorPaginatedResponse(
+            data=[],
+            pagination=CursorPagination(
+                next_cursor=None, items_per_page=10, has_more=False
+            ),
+        )
+        assert response.model_dump(mode="json")["pagination_type"] == "cursor"
+
+    def test_pagination_field_is_typed(self):
+        """pagination field is CursorPagination, not the union."""
+        response = CursorPaginatedResponse(
+            data=[{"id": 1}],
+            pagination=CursorPagination(
+                next_cursor="abc123",
+                prev_cursor=None,
+                items_per_page=20,
+                has_more=True,
+            ),
+        )
+        assert isinstance(response.pagination, CursorPagination)
+        assert response.pagination.next_cursor == "abc123"
+        assert response.pagination.has_more is True
+
+    def test_is_subclass_of_paginated_response(self):
+        """CursorPaginatedResponse IS a PaginatedResponse."""
+        response = CursorPaginatedResponse(
+            data=[],
+            pagination=CursorPagination(
+                next_cursor=None, items_per_page=10, has_more=False
+            ),
+        )
+        assert isinstance(response, PaginatedResponse)
+
+    def test_pagination_type_default_cannot_be_overridden_to_offset(self):
+        """pagination_type rejects values other than CURSOR."""
+        with pytest.raises(ValidationError):
+            CursorPaginatedResponse(
+                data=[],
+                pagination=CursorPagination(
+                    next_cursor=None, items_per_page=10, has_more=False
+                ),
+                pagination_type=PaginationType.OFFSET,  # type: ignore[arg-type]
+            )
+
+    def test_full_serialization(self):
+        """Full JSON serialization includes all expected fields."""
+        response = CursorPaginatedResponse(
+            data=[{"id": 1}],
+            pagination=CursorPagination(
+                next_cursor="tok_next",
+                prev_cursor="tok_prev",
+                items_per_page=10,
+                has_more=True,
+            ),
+        )
+        data = response.model_dump(mode="json")
+
+        assert data["pagination_type"] == "cursor"
+        assert data["status"] == "SUCCESS"
+        assert data["pagination"]["next_cursor"] == "tok_next"
+        assert data["pagination"]["prev_cursor"] == "tok_prev"
+
+
 class TestFromAttributes:
     """Tests for from_attributes config (ORM mode)."""