support for empty chunks

Author: giancarloromeo

packages/models-library/src/models_library/rpc_pagination.py

@@ -30,22 +30,22 @@
 class PageRefsParams(PageRefs[PageQueryParameters]):
     @classmethod
     def create(cls, total: int, limit: int, offset: int) -> "PageRefsParams":
-        last_page = ceil(total / limit) - 1
+        last_page = ceil(total / limit) - 1 if total > 0 else 0
         return cls.model_validate(
             {
                 "self": {"offset": offset, "limit": limit},
                 "first": {"offset": 0, "limit": limit},
                 "prev": (
                     {"offset": max(offset - limit, 0), "limit": limit}
-                    if offset > 0
+                    if offset > 0 and total > 0
                     else None
                 ),
                 "next": (
                     {
                         "offset": min(offset + limit, last_page * limit),
                         "limit": limit,
                     }
-                    if offset < (last_page * limit)
+                    if offset < (last_page * limit) and total > 0
                     else None
                 ),
                 "last": {"offset": last_page * limit, "limit": limit},

packages/models-library/tests/test_rest_pagination.py

@@ -2,7 +2,7 @@
 
 import pytest
 from models_library.rest_pagination import Page, PageMetaInfoLimitOffset
-from pydantic.main import BaseModel
+from pydantic import BaseModel, ValidationError
 from pytest_simcore.examples.models_library import PAGE_EXAMPLES
 
 
@@ -26,7 +26,7 @@ def test_page_response_limit_offset_models(cls_model: BaseModel, examples: list[
 
 
 def test_invalid_offset():
-    with pytest.raises(ValueError):
+    with pytest.raises(ValidationError):
         PageMetaInfoLimitOffset(limit=6, total=5, offset=5, count=2)
 
 
@@ -39,14 +39,14 @@ def test_invalid_offset():
     ],
 )
 def test_invalid_count(count: int, offset: int):
-    with pytest.raises(ValueError):
+    with pytest.raises(ValidationError):
         PageMetaInfoLimitOffset(limit=6, total=5, offset=offset, count=count)
 
 
 def test_data_size_does_not_fit_count():
     example = deepcopy(PAGE_EXAMPLES[0])
     example["_meta"]["count"] = len(example["data"]) - 1
-    with pytest.raises(ValueError):
+    with pytest.raises(ValidationError):
         Page[str](**example)
 
 

packages/pytest-simcore/src/pytest_simcore/examples/models_library.py

@@ -25,6 +25,18 @@
         },
         "data": ["data 5", "data 6", "data 7"],
     },
+    # empty page
+    {
+        "_meta": {"total": 0, "count": 0, "limit": 4, "offset": 0},
+        "_links": {
+            "self": "https://osparc.io/v2/listing?offset=0&limit=4",
+            "first": "https://osparc.io/v2/listing?offset=0&limit=4",
+            "prev": None,
+            "next": None,
+            "last": "https://osparc.io/v2/listing?offset=0&limit=4",
+        },
+        "data": [],
+    },
 ]
 
 RPC_PAGE_EXAMPLES: Final[list[dict]] = [
@@ -52,4 +64,16 @@
         },
         "data": ["data 5", "data 6", "data 7"],
     },
+    # empty page
+    {
+        "_meta": {"total": 0, "count": 0, "limit": 4, "offset": 0},
+        "_links": {
+            "self": {"offset": 0, "limit": 4},
+            "first": {"offset": 0, "limit": 4},
+            "prev": None,
+            "next": None,
+            "last": {"offset": 0, "limit": 4},
+        },
+        "data": [],
+    },
 ]