Source code for langchain_core.messages.base

from __future__ import annotations

from typing import TYPE_CHECKING, Any, Dict, List, Optional, Sequence, Union

from langchain_core.load.serializable import Serializable
from langchain_core.pydantic_v1 import Extra, Field
from langchain_core.utils import get_bolded_text
from langchain_core.utils._merge import merge_dicts
from langchain_core.utils.interactive_env import is_interactive_env

if TYPE_CHECKING:
    from langchain_core.prompts.chat import ChatPromptTemplate


[docs]class BaseMessage(Serializable): """Base abstract Message class. Messages are the inputs and outputs of ChatModels. """ content: Union[str, List[Union[str, Dict]]] """The string contents of the message.""" additional_kwargs: dict = Field(default_factory=dict) """Reserved for additional payload data associated with the message. For example, for a message from an AI, this could include tool calls.""" response_metadata: dict = Field(default_factory=dict) """Response metadata. For example: response headers, logprobs, token counts.""" type: str name: Optional[str] = None id: Optional[str] = None """An optional unique identifier for the message. This should ideally be provided by the provider/model which created the message.""" class Config: extra = Extra.allow def __init__( self, content: Union[str, List[Union[str, Dict]]], **kwargs: Any ) -> None: """Pass in content as positional arg.""" return super().__init__(content=content, **kwargs)
[docs] @classmethod def is_lc_serializable(cls) -> bool: """Return whether this class is serializable.""" return True
[docs] @classmethod def get_lc_namespace(cls) -> List[str]: """Get the namespace of the langchain object.""" return ["langchain", "schema", "messages"]
def __add__(self, other: Any) -> ChatPromptTemplate: from langchain_core.prompts.chat import ChatPromptTemplate prompt = ChatPromptTemplate(messages=[self]) # type: ignore[call-arg] return prompt + other
[docs] def pretty_repr(self, html: bool = False) -> str: title = get_msg_title_repr(self.type.title() + " Message", bold=html) # TODO: handle non-string content. if self.name is not None: title += f"\nName: {self.name}" return f"{title}\n\n{self.content}"
[docs] def pretty_print(self) -> None: print(self.pretty_repr(html=is_interactive_env())) # noqa: T201
[docs]def merge_content( first_content: Union[str, List[Union[str, Dict]]], second_content: Union[str, List[Union[str, Dict]]], ) -> Union[str, List[Union[str, Dict]]]: """Merge two message contents. Args: first_content: The first content. second_content: The second content. Returns: The merged content. """ # If first chunk is a string if isinstance(first_content, str): # If the second chunk is also a string, then merge them naively if isinstance(second_content, str): return first_content + second_content # If the second chunk is a list, add the first chunk to the start of the list else: return_list: List[Union[str, Dict]] = [first_content] return return_list + second_content # If both are lists, merge them naively elif isinstance(second_content, List): return first_content + second_content # If the first content is a list, and the second content is a string else: # If the last element of the first content is a string # Add the second content to the last element if isinstance(first_content[-1], str): return first_content[:-1] + [first_content[-1] + second_content] else: # Otherwise, add the second content as a new element of the list return first_content + [second_content]
[docs]class BaseMessageChunk(BaseMessage): """Message chunk, which can be concatenated with other Message chunks."""
[docs] @classmethod def get_lc_namespace(cls) -> List[str]: """Get the namespace of the langchain object.""" return ["langchain", "schema", "messages"]
def __add__(self, other: Any) -> BaseMessageChunk: # type: ignore if isinstance(other, BaseMessageChunk): # If both are (subclasses of) BaseMessageChunk, # concat into a single BaseMessageChunk return self.__class__( # type: ignore[call-arg] id=self.id, content=merge_content(self.content, other.content), additional_kwargs=merge_dicts( self.additional_kwargs, other.additional_kwargs ), response_metadata=merge_dicts( self.response_metadata, other.response_metadata ), ) else: raise TypeError( 'unsupported operand type(s) for +: "' f"{self.__class__.__name__}" f'" and "{other.__class__.__name__}"' )
[docs]def message_to_dict(message: BaseMessage) -> dict: """Convert a Message to a dictionary. Args: message: Message to convert. Returns: Message as a dict. """ return {"type": message.type, "data": message.dict()}
[docs]def messages_to_dict(messages: Sequence[BaseMessage]) -> List[dict]: """Convert a sequence of Messages to a list of dictionaries. Args: messages: Sequence of messages (as BaseMessages) to convert. Returns: List of messages as dicts. """ return [message_to_dict(m) for m in messages]
[docs]def get_msg_title_repr(title: str, *, bold: bool = False) -> str: """Get a title representation for a message. Args: title: The title. bold: Whether to bold the title. Returns: The title representation. """ padded = " " + title + " " sep_len = (80 - len(padded)) // 2 sep = "=" * sep_len second_sep = sep + "=" if len(padded) % 2 else sep if bold: padded = get_bolded_text(padded) return f"{sep}{padded}{second_sep}"