Feat: Addition of pagination proxy and Flag functionality (#4)

Co-authored-by: vikbhas <waraa.vignesh@gmail.com>

creyPY/fastapi/pagination.py

@@ -1,10 +1,16 @@
 from math import ceil
-from typing import Any, Generic, Optional, Self, Sequence, TypeVar
+from typing import Any, Generic, Optional, Self, Sequence, TypeVar, Union
 
 from fastapi_pagination import Params
 from fastapi_pagination.bases import AbstractPage, AbstractParams
-from fastapi_pagination.types import GreaterEqualOne, GreaterEqualZero
+from fastapi_pagination.types import GreaterEqualOne, GreaterEqualZero, AdditionalData, SyncItemsTransformer
+from fastapi_pagination.api import create_page, apply_items_transformer
+from fastapi_pagination.utils import verify_params
+from fastapi_pagination.ext.sqlalchemy import create_paginate_query
 from pydantic.json_schema import SkipJsonSchema
+from sqlalchemy.sql.selectable import Select
+from sqlalchemy.orm.session import Session
+from sqlalchemy import select, func
 
 T = TypeVar("T")
 
@@ -70,3 +76,41 @@ def parse_page(response, page: int, size: int) -> Page:
         has_next=response.has_next,
         has_prev=response.has_prev,
     )
+
+def create_count_query(query: Select) -> Select:
+    return select(func.count()).select_from(query.subquery())
+
+def unwrap_scalars(
+    items: Sequence[Sequence[T]],
+    force_unwrap: bool = True,
+) -> Union[Sequence[T], Sequence[Sequence[T]]]:
+    return [item[0] if force_unwrap else item for item in items]
+
+def paginate(connection: Session,
+            query: Select,
+            paginationFlag: bool = True,
+            params: Optional[AbstractParams] = None,
+            transformer: Optional[SyncItemsTransformer] = None,
+            additional_data: Optional[AdditionalData] = None):
+    
+    params, raw_params = verify_params(params, "limit-offset", "cursor")
+    
+    count_query = create_count_query(query)
+    total = connection.scalar(count_query)
+
+    if paginationFlag is False:
+        params = Params(page=1, size=total)
+        
+    query = create_paginate_query(query, params)
+    items = connection.execute(query).all()
+    
+    items = unwrap_scalars(items)
+    t_items = apply_items_transformer(items, transformer)
+    
+    return create_page(
+        t_items,
+        params=params,
+        total=total,
+        **(additional_data or {}),
+    )
+