add optional initial cursor

Author: sinisaos

README.md

@@ -31,7 +31,7 @@ TaskModelOut: t.Any = create_pydantic_model(
 @app.get("/tasks/", response_model=t.List[TaskModelOut])
 async def tasks(
     request: Request,
-    __cursor: str,
+    __cursor: t.Optional[str] = None,
     __previous: t.Optional[str] = None,
 ):
     try:
@@ -50,7 +50,9 @@ async def tasks(
         )
     except KeyError:
         paginator = CursorPagination(cursor=__cursor)
-        rows_result, headers_result = await paginator.get_cursor_rows(Task, request)
+        rows_result, headers_result = await paginator.get_cursor_rows(
+            Task, request
+        )
         rows = await rows_result.run()
         headers = headers_result
         response = JSONResponse(

example/app.py

@@ -41,7 +41,7 @@
 @app.get("/tasks/", response_model=t.List[TaskModelOut])
 async def tasks(
     request: Request,
-    __cursor: str,
+    __cursor: t.Optional[str] = None,
     __previous: t.Optional[str] = None,
 ):
     try:

piccolo_cursor_pagination/pagination.py

@@ -135,10 +135,10 @@ def encode_cursor(self, cursor: str) -> str:
         return base64_bytes.decode("ascii")
 
     async def decode_cursor(self, cursor: str, table: t.Type[Table]) -> int:
+        if cursor is None:
+            cursor = ""
         base64_bytes = cursor.encode("ascii")
         cursor_bytes = base64.b64decode(base64_bytes)
-        # we provide initial cursor like this because
-        # we cannot pass empty string to FastAPI openapi
         initial_cursor = await (
             table.select()
             .order_by(table._meta.primary_key, ascending=False)