Source code for langchain_core.prompt_values

"""**Prompt values** for language model prompts.

Prompt values are used to represent different pieces of prompts.
They can be used to represent text, images, or chat message pieces.
"""

from __future__ import annotations

from abc import ABC, abstractmethod
from collections.abc import Sequence
from typing import Literal, cast

from typing_extensions import TypedDict

from langchain_core.load.serializable import Serializable
from langchain_core.messages import (
    AnyMessage,
    BaseMessage,
    HumanMessage,
    get_buffer_string,
)


[docs] class PromptValue(Serializable, ABC): """Base abstract class for inputs to any language model. PromptValues can be converted to both LLM (pure text-generation) inputs and ChatModel inputs. """ @classmethod def is_lc_serializable(cls) -> bool: """Return whether this class is serializable. Defaults to True.""" return True @classmethod def get_lc_namespace(cls) -> list[str]: """Get the namespace of the langchain object. This is used to determine the namespace of the object when serializing. Defaults to ["langchain", "schema", "prompt"]. """ return ["langchain", "schema", "prompt"]
[docs] @abstractmethod def to_string(self) -> str: """Return prompt value as string."""
[docs] @abstractmethod def to_messages(self) -> list[BaseMessage]: """Return prompt as a list of Messages."""
[docs] class StringPromptValue(PromptValue): """String prompt value.""" text: str """Prompt text.""" type: Literal["StringPromptValue"] = "StringPromptValue" @classmethod def get_lc_namespace(cls) -> list[str]: """Get the namespace of the langchain object. This is used to determine the namespace of the object when serializing. Defaults to ["langchain", "prompts", "base"]. """ return ["langchain", "prompts", "base"]
[docs] def to_string(self) -> str: """Return prompt as string.""" return self.text
[docs] def to_messages(self) -> list[BaseMessage]: """Return prompt as messages.""" return [HumanMessage(content=self.text)]
[docs] class ChatPromptValue(PromptValue): """Chat prompt value. A type of a prompt value that is built from messages. """ messages: Sequence[BaseMessage] """List of messages."""
[docs] def to_string(self) -> str: """Return prompt as string.""" return get_buffer_string(self.messages)
[docs] def to_messages(self) -> list[BaseMessage]: """Return prompt as a list of messages.""" return list(self.messages)
@classmethod def get_lc_namespace(cls) -> list[str]: """Get the namespace of the langchain object. This is used to determine the namespace of the object when serializing. Defaults to ["langchain", "prompts", "chat"]. """ return ["langchain", "prompts", "chat"]
[docs] class ImageURL(TypedDict, total=False): """Image URL.""" detail: Literal["auto", "low", "high"] """Specifies the detail level of the image. Defaults to "auto". Can be "auto", "low", or "high".""" url: str """Either a URL of the image or the base64 encoded image data."""
[docs] class ImagePromptValue(PromptValue): """Image prompt value.""" image_url: ImageURL """Image URL.""" type: Literal["ImagePromptValue"] = "ImagePromptValue"
[docs] def to_string(self) -> str: """Return prompt (image URL) as string.""" return self.image_url["url"]
[docs] def to_messages(self) -> list[BaseMessage]: """Return prompt (image URL) as messages.""" return [HumanMessage(content=[cast(dict, self.image_url)])]
[docs] class ChatPromptValueConcrete(ChatPromptValue): """Chat prompt value which explicitly lists out the message types it accepts. For use in external schemas.""" messages: Sequence[AnyMessage] """Sequence of messages.""" type: Literal["ChatPromptValueConcrete"] = "ChatPromptValueConcrete" @classmethod def get_lc_namespace(cls) -> list[str]: """Get the namespace of the langchain object. This is used to determine the namespace of the object when serializing. Defaults to ["langchain", "prompts", "chat"]. """ return ["langchain", "prompts", "chat"]