Updated CRUDkit

crudkit/core/service.py

@@ -1,7 +1,9 @@
-from typing import Type, TypeVar, Generic
+from typing import Type, TypeVar, Generic, Optional
 from sqlalchemy.orm import Session, with_polymorphic
+from sqlalchemy import inspect, text
 from crudkit.core.base import Version
 from crudkit.core.spec import CRUDSpec
+from crudkit.backend import BackendInfo, make_backend_info
 
 T = TypeVar("T")
 
@@ -9,11 +11,20 @@ def _is_truthy(val):
     return str(val).lower() in ('1', 'true', 'yes', 'on')
 
 class CRUDService(Generic[T]):
-    def __init__(self, model: Type[T], session: Session, polymorphic: bool = False):
+    def __init__(
+        self,
+        model: Type[T],
+        session: Session,
+        polymorphic: bool = False,
+        *,
+        backend: Optional[BackendInfo] = None
+    ):
         self.model = model
         self.session = session
         self.polymorphic = polymorphic
         self.supports_soft_delete = hasattr(model, 'is_deleted')
+        # Cache backend info once. If not provided, derive from session bind.
+        self.backend = backend or make_backend_info(self.session.get_bind())
 
     def get_query(self):
         if self.polymorphic:
@@ -23,14 +34,22 @@ class CRUDService(Generic[T]):
             base_only = with_polymorphic(self.model, [], flat=True)
             return self.session.query(base_only), base_only
 
+    # Helper: default ORDER BY for MSSQL when paginating without explicit order
+    def _default_order_by(self, root_alias):
+        mapper = inspect(self.model)
+        cols = []
+        for col in mapper.primary_key:
+            try:
+                cols.append(getattr(root_alias, col.key))
+            except AttributeError:
+                cols.append(col)
+        return cols or [text("1")]
+
     def get(self, id: int, include_deleted: bool = False) -> T | None:
         query, root_alias = self.get_query()
-
         if self.supports_soft_delete and not include_deleted:
             query = query.filter(getattr(root_alias, "is_deleted") == False)
-
         query = query.filter(getattr(root_alias, "id") == id)
-
         obj = query.first()
         return obj or None
 
@@ -60,9 +79,20 @@ class CRUDService(Generic[T]):
 
             if filters:
                 query = query.filter(*filters)
+
+            # MSSQL: requires ORDER BY when using OFFSET (and SQLA will use OFFSET for limit+offset).
+            paginating = (limit is not None) or (offset is not None and offset != 0)
+            if paginating and not order_by and self.backend.requires_order_by_for_offset:
+                order_by = self._default_order_by(root_alias)
+
             if order_by:
                 query = query.order_by(*order_by)
-            query = query.offset(offset).limit(limit)
+
+            # Only apply offset/limit when not None.
+            if offset is not None and offset != 0:
+                query = query.offset(offset)
+            if limit is not None:
+                query = query.limit(limit)
 
         return query.all()
 
@@ -70,7 +100,6 @@ class CRUDService(Generic[T]):
         obj = self.model(**data)
         self.session.add(obj)
         self.session.commit()
-
         self._log_version("create", obj, actor)
         return obj
 
@@ -78,13 +107,11 @@ class CRUDService(Generic[T]):
         obj = self.get(id)
         if not obj:
             raise ValueError(f"{self.model.__name__} with ID {id} not found.")
-
         valid_fields = {c.name for c in self.model.__table__.columns}
         for k, v in data.items():
             if k in valid_fields:
                 setattr(obj, k, v)
         self.session.commit()
-
         self._log_version("update", obj, actor)
         return obj
 
@@ -92,14 +119,11 @@ class CRUDService(Generic[T]):
         obj = self.session.get(self.model, id)
         if not obj:
             return None
-
         if hard or not self.supports_soft_delete:
             self.session.delete(obj)
         else:
             obj.is_deleted = True
-
         self.session.commit()
-
         self._log_version("delete", obj, actor)
         return obj
 
@@ -108,7 +132,6 @@ class CRUDService(Generic[T]):
             data = obj.as_dict()
         except Exception:
             data = {"error": "Failed to serialize object."}
-
         version = Version(
             model_name=self.model.__name__,
             object_id=obj.id,