default_per_page in Pagination

src/flask_sqlalchemy/extension.py

@@ -807,6 +807,7 @@ def paginate(
         *,
         page: int | None = None,
         per_page: int | None = None,
+        default_per_page: int = 20,
         max_per_page: int | None = None,
         error_out: bool = True,
         count: bool = True,
@@ -843,6 +844,7 @@ def paginate(
             session=self.session(),
             page=page,
             per_page=per_page,
+            default_per_page=default_per_page,
             max_per_page=max_per_page,
             error_out=error_out,
             count=count,

src/flask_sqlalchemy/pagination.py

@@ -47,15 +47,21 @@ def __init__(
         self,
         page: int | None = None,
         per_page: int | None = None,
+        default_per_page: int = 20,
         max_per_page: int | None = 100,
         error_out: bool = True,
         count: bool = True,
         **kwargs: t.Any,
     ) -> None:
         self._query_args = kwargs
+
+        self.default_per_page: int = default_per_page
+        """The default number of items on a page."""
+
         page, per_page = self._prepare_page_args(
             page=page,
             per_page=per_page,
+            default_per_page=self.default_per_page,
             max_per_page=max_per_page,
             error_out=error_out,
         )
@@ -92,6 +98,7 @@ def _prepare_page_args(
         *,
         page: int | None = None,
         per_page: int | None = None,
+        default_per_page: int,
         max_per_page: int | None = None,
         error_out: bool = True,
     ) -> tuple[int, int]:
@@ -112,13 +119,13 @@ def _prepare_page_args(
                     if error_out:
                         abort(404)
 
-                    per_page = 20
+                    per_page = default_per_page
         else:
             if page is None:
                 page = 1
 
             if per_page is None:
-                per_page = 20
+                per_page = default_per_page
 
         if max_per_page is not None:
             per_page = min(per_page, max_per_page)
@@ -133,7 +140,7 @@ def _prepare_page_args(
             if error_out:
                 abort(404)
             else:
-                per_page = 20
+                per_page = default_per_page
 
         return page, per_page
 

tests/test_pagination.py

@@ -12,14 +12,25 @@
 
 class RangePagination(Pagination):
     def __init__(
-        self, total: int | None = 150, page: int = 1, per_page: int = 10
+        self,
+        total: int | None = 150,
+        page: int = 1,
+        per_page: int | None = 10,
+        default_per_page: int = 20,
+        error_out: bool = True,
     ) -> None:
         if total is None:
             self._data = range(150)
         else:
             self._data = range(total)
 
-        super().__init__(total=total, page=page, per_page=per_page)
+        super().__init__(
+            total=total,
+            page=page,
+            per_page=per_page,
+            default_per_page=default_per_page,
+            error_out=error_out,
+        )
 
         if total is None:
             self.total = None
@@ -37,6 +48,7 @@ def test_first_page() -> None:
     p = RangePagination()
     assert p.page == 1
     assert p.per_page == 10
+    assert p.default_per_page == 20
     assert p.total == 150
     assert p.pages == 15
     assert not p.has_prev
@@ -74,6 +86,16 @@ def test_item_numbers_0() -> None:
     assert p.last == 0
 
 
+def test_default_per_page_invalid_per_page() -> None:
+    p = RangePagination(per_page=0, default_per_page=10, error_out=False)
+    assert p.per_page == 10
+
+
+def test_default_per_page_none() -> None:
+    p = RangePagination(per_page=None)
+    assert p.per_page == 20
+
+
 @pytest.mark.parametrize("total", [0, None])
 def test_0_pages(total: int | None) -> None:
     p = RangePagination(total=total)