import importlib
import json
import os
from typing import Any, Optional
from langchain_core._api import beta
from langchain_core.load.mapping import (
_JS_SERIALIZABLE_MAPPING,
_OG_SERIALIZABLE_MAPPING,
OLD_CORE_NAMESPACES_MAPPING,
SERIALIZABLE_MAPPING,
)
from langchain_core.load.serializable import Serializable
DEFAULT_NAMESPACES = [
"langchain",
"langchain_core",
"langchain_community",
"langchain_anthropic",
"langchain_groq",
"langchain_google_genai",
"langchain_aws",
"langchain_openai",
"langchain_google_vertexai",
"langchain_mistralai",
"langchain_fireworks",
"langchain_xai",
]
# Namespaces for which only deserializing via the SERIALIZABLE_MAPPING is allowed.
# Load by path is not allowed.
DISALLOW_LOAD_FROM_PATH = [
"langchain_community",
"langchain",
]
ALL_SERIALIZABLE_MAPPINGS = {
**SERIALIZABLE_MAPPING,
**OLD_CORE_NAMESPACES_MAPPING,
**_OG_SERIALIZABLE_MAPPING,
**_JS_SERIALIZABLE_MAPPING,
}
[docs]
class Reviver:
"""Reviver for JSON objects."""
[docs]
def __init__(
self,
secrets_map: Optional[dict[str, str]] = None,
valid_namespaces: Optional[list[str]] = None,
secrets_from_env: bool = True,
additional_import_mappings: Optional[
dict[tuple[str, ...], tuple[str, ...]]
] = None,
) -> None:
"""Initialize the reviver.
Args:
secrets_map: A map of secrets to load. If a secret is not found in
the map, it will be loaded from the environment if `secrets_from_env`
is True. Defaults to None.
valid_namespaces: A list of additional namespaces (modules)
to allow to be deserialized. Defaults to None.
secrets_from_env: Whether to load secrets from the environment.
Defaults to True.
additional_import_mappings: A dictionary of additional namespace mappings
You can use this to override default mappings or add new mappings.
Defaults to None.
"""
self.secrets_from_env = secrets_from_env
self.secrets_map = secrets_map or {}
# By default, only support langchain, but user can pass in additional namespaces
self.valid_namespaces = (
[*DEFAULT_NAMESPACES, *valid_namespaces]
if valid_namespaces
else DEFAULT_NAMESPACES
)
self.additional_import_mappings = additional_import_mappings or {}
self.import_mappings = (
{
**ALL_SERIALIZABLE_MAPPINGS,
**self.additional_import_mappings,
}
if self.additional_import_mappings
else ALL_SERIALIZABLE_MAPPINGS
)
def __call__(self, value: dict[str, Any]) -> Any:
if (
value.get("lc") == 1
and value.get("type") == "secret"
and value.get("id") is not None
):
[key] = value["id"]
if key in self.secrets_map:
return self.secrets_map[key]
else:
if self.secrets_from_env and key in os.environ and os.environ[key]:
return os.environ[key]
msg = f'Missing key "{key}" in load(secrets_map)'
raise KeyError(msg)
if (
value.get("lc") == 1
and value.get("type") == "not_implemented"
and value.get("id") is not None
):
msg = (
"Trying to load an object that doesn't implement "
f"serialization: {value}"
)
raise NotImplementedError(msg)
if (
value.get("lc") == 1
and value.get("type") == "constructor"
and value.get("id") is not None
):
[*namespace, name] = value["id"]
mapping_key = tuple(value["id"])
if (
namespace[0] not in self.valid_namespaces
# The root namespace ["langchain"] is not a valid identifier.
or namespace == ["langchain"]
):
msg = f"Invalid namespace: {value}"
raise ValueError(msg)
# Has explicit import path.
elif mapping_key in self.import_mappings:
import_path = self.import_mappings[mapping_key]
# Split into module and name
import_dir, name = import_path[:-1], import_path[-1]
# Import module
mod = importlib.import_module(".".join(import_dir))
elif namespace[0] in DISALLOW_LOAD_FROM_PATH:
msg = (
"Trying to deserialize something that cannot "
"be deserialized in current version of langchain-core: "
f"{mapping_key}."
)
raise ValueError(msg)
# Otherwise, treat namespace as path.
else:
mod = importlib.import_module(".".join(namespace))
cls = getattr(mod, name)
# The class must be a subclass of Serializable.
if not issubclass(cls, Serializable):
msg = f"Invalid namespace: {value}"
raise ValueError(msg)
# We don't need to recurse on kwargs
# as json.loads will do that for us.
kwargs = value.get("kwargs", {})
return cls(**kwargs)
return value
[docs]
@beta()
def loads(
text: str,
*,
secrets_map: Optional[dict[str, str]] = None,
valid_namespaces: Optional[list[str]] = None,
secrets_from_env: bool = True,
additional_import_mappings: Optional[dict[tuple[str, ...], tuple[str, ...]]] = None,
) -> Any:
"""Revive a LangChain class from a JSON string.
Equivalent to `load(json.loads(text))`.
Args:
text: The string to load.
secrets_map: A map of secrets to load. If a secret is not found in
the map, it will be loaded from the environment if `secrets_from_env`
is True. Defaults to None.
valid_namespaces: A list of additional namespaces (modules)
to allow to be deserialized. Defaults to None.
secrets_from_env: Whether to load secrets from the environment.
Defaults to True.
additional_import_mappings: A dictionary of additional namespace mappings
You can use this to override default mappings or add new mappings.
Defaults to None.
Returns:
Revived LangChain objects.
"""
return json.loads(
text,
object_hook=Reviver(
secrets_map, valid_namespaces, secrets_from_env, additional_import_mappings
),
)
[docs]
@beta()
def load(
obj: Any,
*,
secrets_map: Optional[dict[str, str]] = None,
valid_namespaces: Optional[list[str]] = None,
secrets_from_env: bool = True,
additional_import_mappings: Optional[dict[tuple[str, ...], tuple[str, ...]]] = None,
) -> Any:
"""Revive a LangChain class from a JSON object. Use this if you already
have a parsed JSON object, eg. from `json.load` or `orjson.loads`.
Args:
obj: The object to load.
secrets_map: A map of secrets to load. If a secret is not found in
the map, it will be loaded from the environment if `secrets_from_env`
is True. Defaults to None.
valid_namespaces: A list of additional namespaces (modules)
to allow to be deserialized. Defaults to None.
secrets_from_env: Whether to load secrets from the environment.
Defaults to True.
additional_import_mappings: A dictionary of additional namespace mappings
You can use this to override default mappings or add new mappings.
Defaults to None.
Returns:
Revived LangChain objects.
"""
reviver = Reviver(
secrets_map, valid_namespaces, secrets_from_env, additional_import_mappings
)
def _load(obj: Any) -> Any:
if isinstance(obj, dict):
# Need to revive leaf nodes before reviving this node
loaded_obj = {k: _load(v) for k, v in obj.items()}
return reviver(loaded_obj)
if isinstance(obj, list):
return [_load(o) for o in obj]
return obj
return _load(obj)
