LangChain v0.3 Released With Key Upgrades for Python and JavaScript

LangChain
has
announced
the
release
of
version
0.3,
bringing
significant
upgrades
and
improvements
to
both
Python
and
JavaScript
ecosystems,
according
to
the

LangChain
Blog.

What’s
Changed

Python

All
packages
have
been
upgraded
from
Pydantic
1
to
Pydantic
2
internally,
fully
supporting
the
use
of
Pydantic
2
in
user
code
without
the
need
for
bridges
like

langchain_core.pydantic_v1
or

pydantic.v1.
Pydantic
1,
which
reached
its
end-of-life
in
June
2024,
will
no
longer
be
supported.
Additionally,
Python
3.8
support
will
be
discontinued
as
its
end-of-life
is
scheduled
for
October
2024.

JavaScript

All
LangChain
packages
now
list

@langchain/core
as
a
peer
dependency
instead
of
a
direct
dependency
to
avoid
type
errors
related
to
core
version
conflicts.
Users
must
explicitly
install

@langchain/core
rather
than
relying
on
an
internally
resolved
version
from
other
packages.
Other
changes
include
making
callbacks
backgrounded
and
non-blocking
by
default,
and
the
removal
of
deprecated
document
loader
and
self-query
entrypoints
from

langchain
in
favor
of
entrypoints
in

@langchain/community
and
integration
packages.
Deprecated
Google
PaLM
entrypoints
have
also
been
removed
in
favor
of
entrypoints
in

@langchain/google-vertexai
and

@langchain/google-genai.
Furthermore,
objects
with
a
"type"
as
a


BaseMessageLike
are
deprecated
in
favor
of
the
more
OpenAI-like


MessageWithRole.

What’s
New

LangChain
v0.3
introduces
several
new
features
and
improvements:

• More
  integrations
  have
  been
  moved
  from
  
langchain-community
  to
  their
  own
  
langchain-{name}
  packages,
  allowing
  better
  dependency
  management,
  testing,
  and
  versioning.
  The
  legacy
  implementations
  remain
  in
  
langchain-community
  but
  are
  marked
  as
  deprecated.
• Revamped
  integration
  docs
  and
  API
  references.
• Simplified
  tool
  definition
  and
  usage.
• New
  utilities
  for
  interacting
  with
  chat
  models,
  including
  a
  universal
  model
  constructor,
  message
  trimming,
  filtering
  and
  merging
  utilities,
  and
  a
  rate
  limiter.
• Ability
  to
  dispatch
  custom
  events.

How
to
Update
Your
Code

To
assist
users
in
migrating
to
LangChain
v0.3,
detailed
how-to
guides
for
both
Python
and
JavaScript
are
available.

Documentation

LangChain
documentation
is
versioned,
and
previous
versions
will
remain
accessible
at
their
respective
URLs.

LangGraph

LangGraph
is
a
library
for
building
stateful,
multi-actor
applications
with
LLMs.
As
of
LangChain
v0.2,
LangGraph
is
the
recommended
way
to
build
agents.
It
includes
a
pre-built
LangGraph
object
equivalent
to
the
LangChain
AgentExecutor,
simplifying
the
use
of
out-of-the-box
agent
solutions.

What’s
Coming

The
LangChain
team
is
planning
further
improvements
to
LangChain’s
multi-modal
capabilities
and
continues
to
work
on
enhancing
documentation
and
integration
reliability.

Image
source:
Shutterstock