DB reads make their projection(+similarity) explicit where needed (#20)

* all find invocations make their projection(+similarity) explicit where needed across all classes

* leave the _NOT_SET special object out of type hints for clarity to users

libs/astradb/langchain_astradb/document_loaders.py

@@ -23,6 +23,8 @@
 
 logger = logging.getLogger(__name__)
 
+_NOT_SET = object()
+
 
 class AstraDBLoader(BaseLoader):
     def __init__(
@@ -35,7 +37,7 @@ def __init__(
         async_astra_db_client: Optional[AsyncAstraDB] = None,
         namespace: Optional[str] = None,
         filter_criteria: Optional[Dict[str, Any]] = None,
-        projection: Optional[Dict[str, Any]] = None,
+        projection: Optional[Dict[str, Any]] = _NOT_SET,  # type: ignore[assignment]
         find_options: Optional[Dict[str, Any]] = None,
         nb_prefetched: int = 1000,
         page_content_mapper: Callable[[Dict], str] = json.dumps,
@@ -55,7 +57,8 @@ def __init__(
             namespace: namespace (aka keyspace) where the
                 collection is. Defaults to the database's "default namespace".
             filter_criteria: Criteria to filter documents.
-            projection: Specifies the fields to return.
+            projection: Specifies the fields to return. If not provided, reads
+                fall back to the Data API default projection.
             find_options: Additional options for the query.
             nb_prefetched: Max number of documents to pre-fetch. Defaults to 1000.
             page_content_mapper: Function applied to collection documents to create
@@ -72,7 +75,9 @@ def __init__(
         )
         self.astra_db_env = astra_db_env
         self.filter = filter_criteria
-        self.projection = projection
+        self._projection: Optional[Dict[str, Any]] = (
+            projection if projection is not _NOT_SET else {"*": True}
+        )
         self.find_options = find_options or {}
         self.nb_prefetched = nb_prefetched
         self.page_content_mapper = page_content_mapper
@@ -94,7 +99,7 @@ def lazy_load(self) -> Iterator[Document]:
         for doc in self.astra_db_env.collection.paginated_find(
             filter=self.filter,
             options=self.find_options,
-            projection=self.projection,
+            projection=self._projection,
             sort=None,
             prefetched=self.nb_prefetched,
         ):
@@ -108,7 +113,7 @@ async def alazy_load(self) -> AsyncIterator[Document]:
         async for doc in self.astra_db_env.async_collection.paginated_find(
             filter=self.filter,
             options=self.find_options,
-            projection=self.projection,
+            projection=self._projection,
             sort=None,
             prefetched=self.nb_prefetched,
         ):

libs/astradb/langchain_astradb/storage.py

@@ -57,15 +57,19 @@ def encode_value(self, value: Optional[V]) -> Any:
     def mget(self, keys: Sequence[str]) -> List[Optional[V]]:
         self.astra_env.ensure_db_setup()
         docs_dict = {}
-        for doc in self.collection.paginated_find(filter={"_id": {"$in": list(keys)}}):
+        for doc in self.collection.paginated_find(
+            filter={"_id": {"$in": list(keys)}},
+            projection={"*": True},
+        ):
             docs_dict[doc["_id"]] = doc.get("value")
         return [self.decode_value(docs_dict.get(key)) for key in keys]
 
     async def amget(self, keys: Sequence[str]) -> List[Optional[V]]:
         await self.astra_env.aensure_db_setup()
         docs_dict = {}
         async for doc in self.async_collection.paginated_find(
-            filter={"_id": {"$in": list(keys)}}
+            filter={"_id": {"$in": list(keys)}},
+            projection={"*": True},
         ):
             docs_dict[doc["_id"]] = doc.get("value")
         return [self.decode_value(docs_dict.get(key)) for key in keys]