langchain_community() — langchain Function Reference

Source Code

libs/langchain/langchain_classic/chains/api/base.py lines 57–386

    from langchain_community.utilities.requests import TextRequestsWrapper

    @deprecated(
        since="0.2.13",
        message=(
            "This class is deprecated and will be removed in langchain 1.0. "
            "See API reference for replacement: "
            "https://api.python.langchain.com/en/latest/chains/langchain.chains.api.base.APIChain.html"
        ),
        removal="1.0",
    )
    class APIChain(Chain):
        """Chain that makes API calls and summarizes the responses to answer a question.

        **Security Note**: This API chain uses the requests toolkit
            to make `GET`, `POST`, `PATCH`, `PUT`, and `DELETE` requests to an API.

            Exercise care in who is allowed to use this chain. If exposing
            to end users, consider that users will be able to make arbitrary
            requests on behalf of the server hosting the code. For example,
            users could ask the server to make a request to a private API
            that is only accessible from the server.

            Control access to who can submit issue requests using this toolkit and
            what network access it has.

            See https://docs.langchain.com/oss/python/security-policy for more
            information.

        !!! note
            This class is deprecated. See below for a replacement implementation using
            LangGraph. The benefits of this implementation are:

        - Uses LLM tool calling features to encourage properly-formatted API requests;
        - Support for both token-by-token and step-by-step streaming;
        - Support for checkpointing and memory of chat history;
        - Easier to modify or extend
            (e.g., with additional tools, structured responses, etc.)

        Install LangGraph with:

        ```bash
        pip install -U langgraph
        ```

        ```python
        from typing import Annotated, Sequence
        from typing_extensions import TypedDict

        from langchain_classic.chains.api.prompt import API_URL_PROMPT
        from langchain_community.agent_toolkits.openapi.toolkit import RequestsToolkit
        from langchain_community.utilities.requests import TextRequestsWrapper
        from langchain_core.messages import BaseMessage
        from langchain_core.prompts import ChatPromptTemplate
        from langchain_openai import ChatOpenAI
        from langchain_core.runnables import RunnableConfig
        from langgraph.graph import END, StateGraph
        from langgraph.graph.message import add_messages
        from langgraph.prebuilt.tool_node import ToolNode

        # NOTE: There are inherent risks in giving models discretion
        # to execute real-world actions. We must "opt-in" to these
        # risks by setting allow_dangerous_request=True to use these tools.
        # This can be dangerous for calling unwanted requests. Please make
        # sure your custom OpenAPI spec (yaml) is safe and that permissions
        # associated with the tools are narrowly-scoped.
        ALLOW_DANGEROUS_REQUESTS = True

        # Subset of spec for https://jsonplaceholder.typicode.com
        api_spec = \"\"\"
        openapi: 3.0.0
        info:
          title: JSONPlaceholder API
          version: 1.0.0
        servers:
          - url: https://jsonplaceholder.typicode.com
        paths:
          /posts:
            get:
              summary: Get posts
              parameters: &id001