create_stuff_documents_chain() — langchain Function Reference

Source Code

libs/langchain/langchain_classic/chains/combine_documents/stuff.py lines 25–101

def create_stuff_documents_chain(
    llm: LanguageModelLike,
    prompt: BasePromptTemplate,
    *,
    output_parser: BaseOutputParser | None = None,
    document_prompt: BasePromptTemplate | None = None,
    document_separator: str = DEFAULT_DOCUMENT_SEPARATOR,
    document_variable_name: str = DOCUMENTS_KEY,
) -> Runnable[dict[str, Any], Any]:
    r"""Create a chain for passing a list of Documents to a model.

    Args:
        llm: Language model.
        prompt: Prompt template. Must contain input variable `"context"` (override by
            setting document_variable), which will be used for passing in the formatted
            documents.
        output_parser: Output parser. Defaults to `StrOutputParser`.
        document_prompt: Prompt used for formatting each document into a string. Input
            variables can be "page_content" or any metadata keys that are in all
            documents. "page_content" will automatically retrieve the
            `Document.page_content`, and all other inputs variables will be
            automatically retrieved from the `Document.metadata` dictionary. Default to
            a prompt that only contains `Document.page_content`.
        document_separator: String separator to use between formatted document strings.
        document_variable_name: Variable name to use for the formatted documents in the
            prompt. Defaults to `"context"`.

    Returns:
        An LCEL Runnable. The input is a dictionary that must have a `"context"` key
        that maps to a `list[Document]`, and any other input variables expected in the
        prompt. The `Runnable` return type depends on `output_parser` used.

    Example:
        ```python
        # pip install -U langchain langchain-openai

        from langchain_openai import ChatOpenAI
        from langchain_core.documents import Document
        from langchain_core.prompts import ChatPromptTemplate
        from langchain_classic.chains.combine_documents import (
            create_stuff_documents_chain,
        )

        prompt = ChatPromptTemplate.from_messages(
            [("system", "What are everyone's favorite colors:\n\n{context}")]
        )
        model = ChatOpenAI(model="gpt-3.5-turbo")
        chain = create_stuff_documents_chain(model, prompt)

        docs = [
            Document(page_content="Jesse loves red but not yellow"),
            Document(
                page_content="Jamal loves green but not as much as he loves orange"
            ),
        ]

        chain.invoke({"context": docs})
        ```
    """
    _validate_prompt(prompt, document_variable_name)
    _document_prompt = document_prompt or DEFAULT_DOCUMENT_PROMPT
    _output_parser = output_parser or StrOutputParser()

    def format_docs(inputs: dict) -> str:
        return document_separator.join(
            format_document(doc, _document_prompt)
            for doc in inputs[document_variable_name]
        )

    return (
        RunnablePassthrough.assign(**{document_variable_name: format_docs}).with_config(
            run_name="format_inputs",
        )
        | prompt
        | llm
        | _output_parser
    ).with_config(run_name="stuff_documents_chain")