from collections.abc import Iterator, Mapping, Sequence
from typing import (
Any,
Callable,
Optional,
Union,
)
from pydantic import BaseModel, Field
from langchain_core._api.beta_decorator import beta
from langchain_core.language_models.base import BaseLanguageModel
from langchain_core.prompts.chat import (
ChatPromptTemplate,
MessageLikeRepresentation,
)
from langchain_core.prompts.string import PromptTemplateFormat
from langchain_core.runnables.base import (
Other,
Runnable,
RunnableSequence,
RunnableSerializable,
)
from langchain_core.utils import get_pydantic_field_names
[docs]
@beta()
class StructuredPrompt(ChatPromptTemplate):
"""Structured prompt template for a language model."""
schema_: Union[dict, type[BaseModel]]
"""Schema for the structured prompt."""
structured_output_kwargs: dict[str, Any] = Field(default_factory=dict)
def __init__(
self,
messages: Sequence[MessageLikeRepresentation],
schema_: Optional[Union[dict, type[BaseModel]]] = None,
*,
structured_output_kwargs: Optional[dict[str, Any]] = None,
template_format: PromptTemplateFormat = "f-string",
**kwargs: Any,
) -> None:
schema_ = schema_ or kwargs.pop("schema")
structured_output_kwargs = structured_output_kwargs or {}
for k in set(kwargs).difference(get_pydantic_field_names(self.__class__)):
structured_output_kwargs[k] = kwargs.pop(k)
super().__init__(
messages=messages,
schema_=schema_,
structured_output_kwargs=structured_output_kwargs,
template_format=template_format,
**kwargs,
)
@classmethod
def get_lc_namespace(cls) -> list[str]:
"""Get the namespace of the langchain object.
For example, if the class is `langchain.llms.openai.OpenAI`, then the
namespace is ["langchain", "llms", "openai"]
"""
return cls.__module__.split(".")
[docs]
@classmethod
def from_messages_and_schema(
cls,
messages: Sequence[MessageLikeRepresentation],
schema: Union[dict, type[BaseModel]],
**kwargs: Any,
) -> ChatPromptTemplate:
"""Create a chat prompt template from a variety of message formats.
Examples:
Instantiation from a list of message templates:
.. code-block:: python
from langchain_core.prompts import StructuredPrompt
class OutputSchema(BaseModel):
name: str
value: int
template = StructuredPrompt(
[
("human", "Hello, how are you?"),
("ai", "I'm doing well, thanks!"),
("human", "That's good to hear."),
],
OutputSchema,
)
Args:
messages: sequence of message representations.
A message can be represented using the following formats:
(1) BaseMessagePromptTemplate, (2) BaseMessage, (3) 2-tuple of
(message type, template); e.g., ("human", "{user_input}"),
(4) 2-tuple of (message class, template), (5) a string which is
shorthand for ("human", template); e.g., "{user_input}"
schema: a dictionary representation of function call, or a Pydantic model.
kwargs: Any additional kwargs to pass through to
``ChatModel.with_structured_output(schema, **kwargs)``.
Returns:
a structured prompt template
"""
return cls(messages, schema, **kwargs)
def __or__(
self,
other: Union[
Runnable[Any, Other],
Callable[[Any], Other],
Callable[[Iterator[Any]], Iterator[Other]],
Mapping[str, Union[Runnable[Any, Other], Callable[[Any], Other], Any]],
],
) -> RunnableSerializable[dict, Other]:
return self.pipe(other)
def pipe(
self,
*others: Union[
Runnable[Any, Other],
Callable[[Any], Other],
Callable[[Iterator[Any]], Iterator[Other]],
Mapping[str, Union[Runnable[Any, Other], Callable[[Any], Other], Any]],
],
name: Optional[str] = None,
) -> RunnableSerializable[dict, Other]:
"""Pipe the structured prompt to a language model.
Args:
others: The language model to pipe the structured prompt to.
name: The name of the pipeline. Defaults to None.
Returns:
A RunnableSequence object.
Raises:
NotImplementedError: If the first element of `others`
is not a language model.
"""
if (
others
and isinstance(others[0], BaseLanguageModel)
or hasattr(others[0], "with_structured_output")
):
return RunnableSequence(
self,
others[0].with_structured_output(
self.schema_, **self.structured_output_kwargs
),
*others[1:],
name=name,
)
else:
msg = "Structured prompts need to be piped to a language model."
raise NotImplementedError(msg)
