3/21 從日本旅行回來後感覺有很多東西要學, 但卻不知從哪一個著手. 昨天整理書桌看到案上的 LangChain 書籍, 想說那就從 LangChain 開始吧! 記得 LangChain 就是去年九月第一次關西之旅回來後開始學習的.
由於我的 LG Gram 筆電的 Thonny Python 執行環境太亂了, 存在嚴重的版本衝突問題, 所以在重新出發之前, 先建立一個專門用來串接 GenAI 的乾淨虛擬環境較好. 我之前曾使用 poetry 來建立與管理虛擬環境, 但本篇則是要使用傳統且熟悉的 venv.
其中 langchain-google-genai 與 langchain-openai 分別是串接 Gemini 與 OpenAI 的外掛, 安裝它們時會自動安裝 LangChain 的核心引擎 langchain-core, 這是 LangChain 的心臟, 包含所有的基礎邏輯 (Base Message, Chat Prompt 等), 安裝外掛時會自動附帶. 注意, 不需要安裝 langchain 套件, 這是一個塞滿了各種實驗性功能和舊代碼的大禮包, 非常龐雜.
(myvenv) D:\python\test>pip install langchain-google-genai langchain-openai python-dotenv
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Installing collected packages: filetype, zstandard, xxhash, websockets, uuid-utils, urllib3, typing-extensions, tenacity, sniffio, regex, pyyaml, python-dotenv, pycparser, pyasn1, packaging, orjson, jsonpointer, jiter, idna, h11, distro, colorama, charset_normalizer, certifi, annotated-types, typing-inspection, tqdm, requests, pydantic-core, pyasn1-modules, jsonpatch, httpcore, cffi, anyio, tiktoken, requests-toolbelt, pydantic, httpx, cryptography, openai, langsmith, google-auth, langchain-core, langchain-openai, google-genai, langchain-google-genai
Successfully installed annotated-types-0.7.0 anyio-4.13.0 certifi-2026.2.25 cffi-2.0.0 charset_normalizer-3.4.7 colorama-0.4.6 cryptography-46.0.6 distro-1.9.0 filetype-1.2.0 google-auth-2.49.1 google-genai-1.70.0 h11-0.16.0 httpcore-1.0.9 httpx-0.28.1 idna-3.11 jiter-0.13.0 jsonpatch-1.33 jsonpointer-3.1.1 langchain-core-1.2.26 langchain-google-genai-4.2.1 langchain-openai-1.1.12 langsmith-0.7.25 openai-2.30.0 orjson-3.11.8 packaging-26.0 pyasn1-0.6.3 pyasn1-modules-0.4.2 pycparser-3.0 pydantic-2.12.5 pydantic-core-2.41.5 python-dotenv-1.2.2 pyyaml-6.0.3 regex-2026.4.4 requests-2.33.1 requests-toolbelt-1.0.0 sniffio-1.3.1 tenacity-9.1.4 tiktoken-0.12.0 tqdm-4.67.3 typing-extensions-4.15.0 typing-inspection-0.4.2 urllib3-2.6.3 uuid-utils-0.14.1 websockets-16.0 xxhash-3.6.0 zstandard-0.25.0
可見除了核心套件 langchain-core 外, 還有串接 OpenAI 與 Gemini 的 langchain-openai 與 langchain-google-genai 套件; 此外還會安裝底層的 SDK 依賴套件 google-genai 與 openai. 如果想用原生 SDK 串接 API 就可以使用這兩個套件. 其中 google-genai 是谷歌 2024 年底發布的新版 SDK, 用來取代舊版的 google-generativeai (已於 2025 年進入維護模式), 用法參考下面這篇的補充說明 :