[Bug fix] Fix vertex ai integration issue (#1257)

embedchain/llm/vertex_ai.py

@@ -2,6 +2,9 @@ import importlib
 import logging
 from typing import Optional
 
+from langchain.callbacks.streaming_stdout import StreamingStdOutCallbackHandler
+from langchain_google_vertexai import ChatVertexAI
+
 from embedchain.config import BaseLlmConfig
 from embedchain.helpers.json_serializable import register_deserializable
 from embedchain.llm.base import BaseLlm
@@ -24,13 +27,17 @@ class VertexAILlm(BaseLlm):
 
     @staticmethod
     def _get_answer(prompt: str, config: BaseLlmConfig) -> str:
-        from langchain_community.chat_models import ChatVertexAI
-
-        chat = ChatVertexAI(temperature=config.temperature, model=config.model)
-
         if config.top_p and config.top_p != 1:
             logging.warning("Config option `top_p` is not supported by this model.")
 
         messages = BaseLlm._get_messages(prompt, system_prompt=config.system_prompt)
 
-        return chat(messages).content
+        if config.stream:
+            callbacks = config.callbacks if config.callbacks else [StreamingStdOutCallbackHandler()]
+            llm = ChatVertexAI(
+                temperature=config.temperature, model=config.model, callbacks=callbacks, streaming=config.stream
+            )
+        else:
+            llm = ChatVertexAI(temperature=config.temperature, model=config.model)
+
+        return llm.invoke(messages).content