How to customize the processing process in the request chain?

[Lufffya]

from langchain_community.chat_models import ChatOpenAI
from langchain_core.prompts import ChatPromptTemplate

from ai_academic.prompts.translation import SYSTEM_MESSAGE

_prompt = ChatPromptTemplate.from_messages(
    [
        ("system", SYSTEM_MESSAGE),
        ("human", "{text}"),
    ]
)
_model = ChatOpenAI()

chain = _prompt | _model

For example, if a file name is passed in, I want to determine in the server what the file name is by reading a pre-existing file, parsing it into text, and inputting it into the model.

Specifically, "HI" will be replaced by "HI.txt". I judge that if it is a file, read the file content as model input.

[eyurtsev]

Prepend a runnable lambda to your chain to manipulate the input. (This is more of an LCEL question rather than langserve.)