Update api.py (#357)

更改目前流式对话的传入模式，使其可以支持多轮对话，体现在新增参数：history、knowledge_base_id

api.py

@@ -265,6 +265,10 @@ async def chat(
 
 async def stream_chat(websocket: WebSocket, knowledge_base_id: str):
     await websocket.accept()
+    turn = 1
+    while True:
+        input_json = await websocket.receive_json()
+        question, history, knowledge_base_id = input_json[""], input_json["history"], input_json["knowledge_base_id"]
         vs_path = os.path.join(VS_ROOT_PATH, knowledge_base_id)
 
         if not os.path.exists(vs_path):
@@ -272,10 +276,6 @@ async def stream_chat(websocket: WebSocket, knowledge_base_id: str):
             await websocket.close()
             return
 
-    history = []
-    turn = 1
-    while True:
-        question = await websocket.receive_text()
         await websocket.send_json({"question": question, "turn": turn, "flag": "start"})
 
         last_print_len = 0
@@ -304,7 +304,6 @@ async def stream_chat(websocket: WebSocket, knowledge_base_id: str):
         )
         turn += 1
 
-
 async def document():
     return RedirectResponse(url="/docs")