Update app.py

app.py

@@ -20,9 +20,11 @@ _ = load_dotenv(find_dotenv())
 
 #openai.api_key = os.environ["OPENAI_API_KEY"]
 
-mongodb_atlas_cluster_uri = os.environ["MONGODB_ATLAS_CLUSTER_URI"]
-client = MongoClient(mongodb_atlas_cluster_uri)
-MONGODB_COLLECTION = client["langchain_db"]["gpt-4"]
+MONGODB_URI = os.environ["MONGODB_ATLAS_CLUSTER_URI"]
+client = MongoClient(MONGODB_URI)
+MONGODB_DB_NAME = "langchain_db"
+MONGODB_COLLECTION_NAME = "gpt-4"
+MONGODB_COLLECTION = client[MONGODB_DB_NAME][MONGODB_COLLECTION_NAME]
 MONGODB_INDEX_NAME = "default"
 
 template = """If you don't know the answer, just say that you don't know, don't try to make up an answer. Keep the answer as concise as possible. Always say 
@@ -85,9 +87,10 @@ def document_retrieval_chroma(llm, prompt):
     return db
 
 def document_retrieval_mongodb(llm, prompt):
-    #TODO    
-    db = Chroma(embedding_function = OpenAIEmbeddings(),
-                persist_directory = CHROMA_DIR)
+    db = MongoDBAtlasVectorSearch.from_connection_string(MONGODB_URI,
+                                                         MONGODB_DB_NAME + "." + MONGODB_COLLECTION_NAME,
+                                                         OpenAIEmbeddings(disallowed_special = ()),
+                                                         index_name = MONGODB_INDEX_NAME)
     return db
 
 def llm_chain(llm, prompt):