community: Factorize AstraDB components constructors (#16779)

* Adds `AstraDBEnvironment` class and use it in `AstraDBLoader`,
`AstraDBCache`, `AstraDBSemanticCache`, `AstraDBBaseStore` and
`AstraDBChatMessageHistory`
* Create an `AsyncAstraDB` if we only have an `AstraDB` and vice-versa
so:
  * we always have an instance of `AstraDB`
* we always have an instance of `AsyncAstraDB` for recent versions of
astrapy
* Create collection if not exists in `AstraDBBaseStore`
* Some typing improvements

Note: `AstraDB` `VectorStore` not using `AstraDBEnvironment` at the
moment. This will be done after the `langchain-astradb` package is out.

libs/community/langchain_community/cache.py

@@ -60,12 +60,14 @@ from langchain_core.load.load import loads
 from langchain_core.outputs import ChatGeneration, Generation
 from langchain_core.utils import get_from_env
 
+from langchain_community.utilities.astradb import AstraDBEnvironment
 from langchain_community.vectorstores.redis import Redis as RedisVectorstore
 
 logger = logging.getLogger(__file__)
 
 if TYPE_CHECKING:
     import momento
+    from astrapy.db import AstraDB
     from cassandra.cluster import Session as CassandraSession
 
 
@@ -1262,7 +1264,7 @@ class AstraDBCache(BaseCache):
         collection_name: str = ASTRA_DB_CACHE_DEFAULT_COLLECTION_NAME,
         token: Optional[str] = None,
         api_endpoint: Optional[str] = None,
-        astra_db_client: Optional[Any] = None,  # 'astrapy.db.AstraDB' if passed
+        astra_db_client: Optional[AstraDB] = None,
         namespace: Optional[str] = None,
     ):
         """
@@ -1278,39 +1280,17 @@ class AstraDBCache(BaseCache):
             namespace (Optional[str]): namespace (aka keyspace) where the
                 collection is created. Defaults to the database's "default namespace".
         """
-        try:
-            from astrapy.db import (
-                AstraDB as LibAstraDB,
-            )
-        except (ImportError, ModuleNotFoundError):
-            raise ImportError(
-                "Could not import a recent astrapy python package. "
-                "Please install it with `pip install --upgrade astrapy`."
-            )
-        # Conflicting-arg checks:
-        if astra_db_client is not None:
-            if token is not None or api_endpoint is not None:
-                raise ValueError(
-                    "You cannot pass 'astra_db_client' to AstraDB if passing "
-                    "'token' and 'api_endpoint'."
-                )
-
-        self.collection_name = collection_name
-        self.token = token
-        self.api_endpoint = api_endpoint
-        self.namespace = namespace
-
-        if astra_db_client is not None:
-            self.astra_db = astra_db_client
-        else:
-            self.astra_db = LibAstraDB(
-                token=self.token,
-                api_endpoint=self.api_endpoint,
-                namespace=self.namespace,
-            )
-        self.collection = self.astra_db.create_collection(
-            collection_name=self.collection_name,
+        astra_env = AstraDBEnvironment(
+            token=token,
+            api_endpoint=api_endpoint,
+            astra_db_client=astra_db_client,
+            namespace=namespace,
         )
+        self.astra_db = astra_env.astra_db
+        self.collection = self.astra_db.create_collection(
+            collection_name=collection_name,
+        )
+        self.collection_name = collection_name
 
     @staticmethod
     def _make_id(prompt: str, llm_string: str) -> str:
@@ -1364,7 +1344,7 @@ class AstraDBCache(BaseCache):
     def delete(self, prompt: str, llm_string: str) -> None:
         """Evict from cache if there's an entry."""
         doc_id = self._make_id(prompt, llm_string)
-        return self.collection.delete_one(doc_id)
+        self.collection.delete_one(doc_id)
 
     def clear(self, **kwargs: Any) -> None:
         """Clear cache. This is for all LLMs at once."""
@@ -1395,7 +1375,7 @@ class AstraDBSemanticCache(BaseCache):
         collection_name: str = ASTRA_DB_CACHE_DEFAULT_COLLECTION_NAME,
         token: Optional[str] = None,
         api_endpoint: Optional[str] = None,
-        astra_db_client: Optional[Any] = None,  # 'astrapy.db.AstraDB' if passed
+        astra_db_client: Optional[AstraDB] = None,
         namespace: Optional[str] = None,
         embedding: Embeddings,
         metric: Optional[str] = None,
@@ -1423,22 +1403,13 @@ class AstraDBSemanticCache(BaseCache):
         The default score threshold is tuned to the default metric.
         Tune it carefully yourself if switching to another distance metric.
         """
-        try:
-            from astrapy.db import (
-                AstraDB as LibAstraDB,
-            )
-        except (ImportError, ModuleNotFoundError):
-            raise ImportError(
-                "Could not import a recent astrapy python package. "
-                "Please install it with `pip install --upgrade astrapy`."
-            )
-        # Conflicting-arg checks:
-        if astra_db_client is not None:
-            if token is not None or api_endpoint is not None:
-                raise ValueError(
-                    "You cannot pass 'astra_db_client' to AstraDB if passing "
-                    "'token' and 'api_endpoint'."
-                )
+        astra_env = AstraDBEnvironment(
+            token=token,
+            api_endpoint=api_endpoint,
+            astra_db_client=astra_db_client,
+            namespace=namespace,
+        )
+        self.astra_db = astra_env.astra_db
 
         self.embedding = embedding
         self.metric = metric
@@ -1457,18 +1428,7 @@ class AstraDBSemanticCache(BaseCache):
         self.embedding_dimension = self._get_embedding_dimension()
 
         self.collection_name = collection_name
-        self.token = token
-        self.api_endpoint = api_endpoint
-        self.namespace = namespace
 
-        if astra_db_client is not None:
-            self.astra_db = astra_db_client
-        else:
-            self.astra_db = LibAstraDB(
-                token=self.token,
-                api_endpoint=self.api_endpoint,
-                namespace=self.namespace,
-            )
         self.collection = self.astra_db.create_collection(
             collection_name=self.collection_name,
             dimension=self.embedding_dimension,