Issue importing Lark using SelfQueryRetriever

[threes-was-taken]

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Example Code

from langchain.retrievers.self_query.base import SelfQueryRetriever

SelfQueryRetriever.from_llm(...)

Description

I'm running in a Lambda environment where I keep getting the following stack-trace:

[ERROR] ImportError: Cannot import lark, please install it with 'pip install lark'.
Traceback (most recent call last):
  File "/var/task/src/services/handle-search-query/functions/handler.py", line 14, in main
    return handler(event)
  File "/var/task/src/services/handle-search-query/functions/handler.py", line 9, in handler
    results = search(query)
  File "/var/task/src/modules/ai.py", line 203, in search
    video_retriever = SelfQueryRetriever.from_llm(
  File "/opt/python/langchain/retrievers/self_query/base.py", line 323, in from_llm
    query_constructor = load_query_constructor_runnable(
  File "/opt/python/langchain/chains/query_constructor/base.py", line 361, in load_query_constructor_runnable
    output_parser = StructuredQueryOutputParser.from_components(
  File "/opt/python/langchain/chains/query_constructor/base.py", line 99, in from_components
    ast_parse = get_parser(
  File "/opt/python/langchain/chains/query_constructor/parser.py", line 173, in get_parser
    raise ImportError(

On the Lambda, I have attached a layer where my Python dependencies are available, including Lark.

I was wondering why the not None-check is applied to the QueryTransformer class. Shouldn't it be on the Transformer class since the error states that it's not possible to import Lark? (see code below)

# libs/langchain/langchain/chains/query_constructor/parser.py
try:
    check_package_version("lark", gte_version="1.1.5")
    from lark import Lark, Transformer, v_args
except ImportError:

    def v_args(*args: Any, **kwargs: Any) -> Any:  # type: ignore
        """Dummy decorator for when lark is not installed."""
        return lambda _: None

    Transformer = object  # type: ignore
    Lark = object  # type: ignore


def get_parser(
    allowed_comparators: Optional[Sequence[Comparator]] = None,
    allowed_operators: Optional[Sequence[Operator]] = None,
    allowed_attributes: Optional[Sequence[str]] = None,
) -> Lark:
    """Return a parser for the query language.

    Args:
        allowed_comparators: Optional[Sequence[Comparator]]
        allowed_operators: Optional[Sequence[Operator]]

    Returns:
        Lark parser for the query language.
    """
    # QueryTransformer is None when Lark cannot be imported.
    if QueryTransformer is None:
        raise ImportError(
            "Cannot import lark, please install it with 'pip install lark'."
        )
    transformer = QueryTransformer(
        allowed_comparators=allowed_comparators,
        allowed_operators=allowed_operators,
        allowed_attributes=allowed_attributes,
    )
    return Lark(GRAMMAR, parser="lalr", transformer=transformer, start="program")

Thanks in advance for any help!

System Info

langchain: v0.2.3
platform: Linux (AWS Lambda)
python: 3.11.9
lark: 1.1.9

[dosubot[bot]]

To resolve the ImportError for Lark when using SelfQueryRetriever in an AWS Lambda environment, despite having Lark installed and available in a layer with your Python dependencies, you should ensure that the Lark package is correctly included in the deployment package and that the Lambda function is configured to use the layer properly.

Here are the steps to troubleshoot and resolve the issue:

1. Verify Layer Configuration: Ensure that the layer containing the Lark package is correctly attached to your Lambda function. You can do this in the AWS Management Console by navigating to your Lambda function and checking the "Layers" section.

2. Check Layer Content: Verify that the Lark package is indeed present in the layer. You can do this by downloading the layer ZIP file and inspecting its contents. The Lark package should be in the python/lib/python3.x/site-packages/ directory within the ZIP file.

3. Update Lambda Function Code: Ensure that your Lambda function code is correctly importing the Lark package. Here is an example of how to import and use the SelfQueryRetriever with Lark in your Lambda function:

   import os
   from langchain.chains.query_constructor.base import AttributeInfo
   from langchain.retrievers.self_query.base import SelfQueryRetriever
   from langchain.schema import Document
   from langchain_community.vectorstores import Vectara
   from langchain_openai.chat_models import ChatOpenAI
   
   # Set environment variables for Vectara
   os.environ["VECTARA_API_KEY"] = "<YOUR_VECTARA_API_KEY>"
   os.environ["VECTARA_CORPUS_ID"] = "<YOUR_VECTARA_CORPUS_ID>"
   os.environ["VECTARA_CUSTOMER_ID"] = "<YOUR_VECTARA_CUSTOMER_ID>"
   
   # Define metadata fields and document content description
   metadata_field_info = [
       AttributeInfo(
           name="genre",
           description="The genre of the movie",
           type="string or list[string]",
       ),
       AttributeInfo(
           name="year",
           description="The year the movie was released",
           type="integer",
       ),
       AttributeInfo(
           name="director",
           description="The name of the movie director",
           type="string",
       ),
       AttributeInfo(
           name="rating", description="A 1-10 rating for the movie", type="float"
       ),
   ]
   document_content_description = "Brief summary of a movie"
   llm = ChatOpenAI(temperature=0, model="gpt-4o", max_tokens=4069)
   
   # Instantiate the SelfQueryRetriever
   retriever = SelfQueryRetriever.from_llm(
       llm, Vectara(), document_content_description, metadata_field_info, verbose=True
   )
   
   # Example usage of the retriever
   def lambda_handler(event, context):
       query = event.get('query', 'What are movies about scientists')
       result = retriever.invoke(query)
       return {
           'statusCode': 200,
           'body': result
       }

4. Deploy the Lambda Function: Ensure that you deploy the Lambda function with the correct configuration and that the layer is properly attached.

By following these steps, you should be able to resolve the ImportError for Lark and successfully use the SelfQueryRetriever in your AWS Lambda environment ^[1].

To continue talking to Dosu, mention @dosu.

[threes-was-taken]

@dosu could you pass this to a maintainer?

[dosubot[bot]]

@eyurtsev, this one's a bit out of my wheelhouse, could you step in and provide your guidance?

To continue talking to Dosu, mention @dosu.

[threes-was-taken]

I found out the issue I raised here is Lambda related, so this discussion became irrelevant.