NameError: name '_LanguageModel' is not defined

[vivekpadia70]

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Example Code

from langchain_community.llms.vertexai import VertexAI
    
llm = VertexAI(
        max_output_tokens=1024,
        temperature=0.2,
        top_p=0.8,
        top_k=40,
        verbose=True,
    )

Description

I am trying to initialize vertexai llm in langchain library.
I get the following error with this.

ConfigError: field "client" not yet prepared so the type is still a ForwardRef, you might need to call VertexAI.update_forward_refs().

And when I called this function I got.

NameError: name '_LanguageModel' is not defined

I also went through the source code and tried importing _LanguageModel manually just before the code but it's not working. How can I resolve this?

System Info

!pip install langchain==0.2.6
!pip install -U langchain-community

from langchain_community.llms.vertexai import VertexAI

[dosubot[bot]]

Hey @vivekpadia70! I'm here to help you with any bugs or questions you have in the LangChain library. Let's get to the bottom of this together.

To resolve the ConfigError and NameError when initializing the VertexAI LLM in the LangChain library, follow these steps:

1. Ensure Required Libraries are Installed:
   Make sure you have the google-cloud-aiplatform library installed:

   pip install google-cloud-aiplatform>=1.38.0

2. Update Forward References:
   The error indicates that the client field's type is still a ForwardRef. You need to update the forward references in the VertexAI class. Here is how you can do it:

   from langchain_community.llms.vertexai import VertexAI
   
   # Update forward references
   VertexAI.update_forward_refs()
   
   # Initialize VertexAI
   llm = VertexAI(
       max_output_tokens=1024,
       temperature=0.2,
       top_p=0.8,
       top_k=40,
       verbose=True,
   )

3. Ensure Proper Initialization:
   Make sure the init_vertexai function is correctly called to initialize the Vertex AI environment. Here is an example:

   from langchain_community.llms.vertexai import VertexAI
   from google.auth import default
   
   # Initialize Vertex AI
   credentials, project = default()
   VertexAI.init_vertexai(project=project, credentials=credentials)
   
   # Update forward references
   VertexAI.update_forward_refs()
   
   # Initialize VertexAI
   llm = VertexAI(
       max_output_tokens=1024,
       temperature=0.2,
       top_p=0.8,
       top_k=40,
       verbose=True,
   )

By following these steps, you should be able to resolve the ConfigError and NameError when initializing the VertexAI LLM in the LangChain library ^[1][2][3].

To continue talking to Dosu, mention @dosu.

[vramakri2023]

@dosu
Your above suggestions fails when update_forward_refs() is called with the message "TypeError: localns arguments are not longer accepted."