Releases: LangChain v0.3 #26544

baskaryan · 2024-09-16T18:58:35Z

baskaryan
Sep 16, 2024
Maintainer

LangChain v0.3 is out!

All packages have been upgraded from Pydantic 1 to Pydantic 2 internally. Use of Pydantic 2 in user code is fully supported with all packages without the need for bridges like langchain_core.pydantic_v1 or pydantic.v1.
Pydantic 1 will no longer be supported as it reached its end-of-life in June 2024.
Python 3.8 will no longer be supported as its end-of-life is October 2024.

These are the only breaking changes.

We’ve made a number of non-breaking improvements during the development of LangChain v0.2 that we’d like to highlight here:

Moved more integrations from langchain-community to their own langchain-{name} packages. This is a non-breaking change, as the legacy implementations are left in langchain-community and marked as deprecated. This allows us to better manage the dependencies of, test, and version these integrations. You can see all the latest integration packages in the Python API reference.
Revamped integration docs and API reference. Read more here.
Simplified tool definition and usage. Read more here.
Added utilities for interacting with chat models: universal model constructor, utilities to trim, filter and merge messages, rate limiter.
Added the ability to dispatch custom events.

Check the how-to guide in the docs for guidance on code migration.

LangChain documentation is versioned and documentation for previous versions will remain live at the following URLs: v0.1, v0.2.

Please open an Issue if you come across any bugs.

Please leave comments here if you have any high-level feedback on the above changes, on migration, on the docs, etc.