Fix issue with zero size (#959)

Author: uriyyo

fastapi_pagination/default.py

@@ -62,7 +62,13 @@ def create(
 
         size = params.size if params.size is not None else total
         page = params.page if params.page is not None else 1
-        pages = ceil(total / size) if total is not None else None
+
+        if size == 0:
+            pages = 0
+        elif total is not None:
+            pages = ceil(total / size)
+        else:
+            pages = None
 
         return create_pydantic_model(
             cls,

fastapi_pagination/links/default.py

@@ -24,7 +24,7 @@ def __root_validator__(cls, value: Any) -> Any:
 
             value["links"] = create_links(
                 first={"page": 1},
-                last={"page": ceil(total / size) if total > 0 else 1},
+                last={"page": ceil(total / size) if total > 0 and size > 0 else 1},
                 next={"page": page + 1} if page * size < total else None,
                 prev={"page": page - 1} if page - 1 >= 1 else None,
             )

tests/test_bases.py

@@ -1,6 +1,7 @@
 import re
 from typing import ClassVar, Generic, Optional, Sequence, TypeVar
 
+from fastapi import Query
 from pytest import mark, raises, warns
 
 from fastapi_pagination import Page, Params
@@ -82,6 +83,30 @@ def test_with_custom_options_items_casted():
     }
 
 
+def test_zero_size():
+    class CustomParams(Params):
+        size: Optional[int] = Query(0)
+
+    class CustomPage(Page[T], Generic[T]):
+        size: Optional[int] = None
+
+        __params_type__ = CustomParams
+
+    res = CustomPage[int].create(
+        [],
+        CustomParams(),
+        total=0,
+    )
+
+    assert res.dict() == {
+        "items": [],
+        "page": 1,
+        "pages": 0,
+        "size": 0,
+        "total": 0,
+    }
+
+
 def test_invalid_params_cast():
     with raises(ValueError, match="^Not a 'limit-offset' params$"):
         CursorParams().to_raw_params().as_limit_offset()