Source code for langchain_core.prompts.loading

"""Load prompts."""

import json
import logging
from pathlib import Path
from typing import Callable, Optional, Union

import yaml

from langchain_core.output_parsers.string import StrOutputParser
from langchain_core.prompts.base import BasePromptTemplate
from langchain_core.prompts.chat import ChatPromptTemplate
from langchain_core.prompts.few_shot import FewShotPromptTemplate
from langchain_core.prompts.prompt import PromptTemplate

URL_BASE = "https://raw.githubusercontent.com/hwchase17/langchain-hub/master/prompts/"
logger = logging.getLogger(__name__)


[docs] def load_prompt_from_config(config: dict) -> BasePromptTemplate: """Load prompt from Config Dict. Args: config: Dict containing the prompt configuration. Returns: A PromptTemplate object. Raises: ValueError: If the prompt type is not supported. """ if "_type" not in config: logger.warning("No `_type` key found, defaulting to `prompt`.") config_type = config.pop("_type", "prompt") if config_type not in type_to_loader_dict: msg = f"Loading {config_type} prompt not supported" raise ValueError(msg) prompt_loader = type_to_loader_dict[config_type] return prompt_loader(config)
def _load_template(var_name: str, config: dict) -> dict: """Load template from the path if applicable.""" # Check if template_path exists in config. if f"{var_name}_path" in config: # If it does, make sure template variable doesn't also exist. if var_name in config: msg = f"Both `{var_name}_path` and `{var_name}` cannot be provided." raise ValueError(msg) # Pop the template path from the config. template_path = Path(config.pop(f"{var_name}_path")) # Load the template. if template_path.suffix == ".txt": with open(template_path) as f: template = f.read() else: raise ValueError # Set the template variable to the extracted variable. config[var_name] = template return config def _load_examples(config: dict) -> dict: """Load examples if necessary.""" if isinstance(config["examples"], list): pass elif isinstance(config["examples"], str): with open(config["examples"]) as f: if config["examples"].endswith(".json"): examples = json.load(f) elif config["examples"].endswith((".yaml", ".yml")): examples = yaml.safe_load(f) else: msg = "Invalid file format. Only json or yaml formats are supported." raise ValueError(msg) config["examples"] = examples else: msg = "Invalid examples format. Only list or string are supported." raise ValueError(msg) return config def _load_output_parser(config: dict) -> dict: """Load output parser.""" if "output_parser" in config and config["output_parser"]: _config = config.pop("output_parser") output_parser_type = _config.pop("_type") if output_parser_type == "default": output_parser = StrOutputParser(**_config) else: msg = f"Unsupported output parser {output_parser_type}" raise ValueError(msg) config["output_parser"] = output_parser return config def _load_few_shot_prompt(config: dict) -> FewShotPromptTemplate: """Load the "few shot" prompt from the config.""" # Load the suffix and prefix templates. config = _load_template("suffix", config) config = _load_template("prefix", config) # Load the example prompt. if "example_prompt_path" in config: if "example_prompt" in config: msg = ( "Only one of example_prompt and example_prompt_path should " "be specified." ) raise ValueError(msg) config["example_prompt"] = load_prompt(config.pop("example_prompt_path")) else: config["example_prompt"] = load_prompt_from_config(config["example_prompt"]) # Load the examples. config = _load_examples(config) config = _load_output_parser(config) return FewShotPromptTemplate(**config) def _load_prompt(config: dict) -> PromptTemplate: """Load the prompt template from config.""" # Load the template from disk if necessary. config = _load_template("template", config) config = _load_output_parser(config) template_format = config.get("template_format", "f-string") if template_format == "jinja2": # Disabled due to: # https://github.com/langchain-ai/langchain/issues/4394 msg = ( f"Loading templates with '{template_format}' format is no longer supported " f"since it can lead to arbitrary code execution. Please migrate to using " f"the 'f-string' template format, which does not suffer from this issue." ) raise ValueError(msg) return PromptTemplate(**config)
[docs] def load_prompt( path: Union[str, Path], encoding: Optional[str] = None ) -> BasePromptTemplate: """Unified method for loading a prompt from LangChainHub or local fs. Args: path: Path to the prompt file. encoding: Encoding of the file. Defaults to None. Returns: A PromptTemplate object. Raises: RuntimeError: If the path is a Lang Chain Hub path. """ if isinstance(path, str) and path.startswith("lc://"): msg = ( "Loading from the deprecated github-based Hub is no longer supported. " "Please use the new LangChain Hub at https://smith.langchain.com/hub " "instead." ) raise RuntimeError(msg) return _load_prompt_from_file(path, encoding)
def _load_prompt_from_file( file: Union[str, Path], encoding: Optional[str] = None ) -> BasePromptTemplate: """Load prompt from file.""" # Convert file to a Path object. file_path = Path(file) if isinstance(file, str) else file # Load from either json or yaml. if file_path.suffix == ".json": with open(file_path, encoding=encoding) as f: config = json.load(f) elif file_path.suffix.endswith((".yaml", ".yml")): with open(file_path, encoding=encoding) as f: config = yaml.safe_load(f) else: msg = f"Got unsupported file type {file_path.suffix}" raise ValueError(msg) # Load the prompt from the config now. return load_prompt_from_config(config) def _load_chat_prompt(config: dict) -> ChatPromptTemplate: """Load chat prompt from config""" messages = config.pop("messages") template = messages[0]["prompt"].pop("template") if messages else None config.pop("input_variables") if not template: msg = "Can't load chat prompt without template" raise ValueError(msg) return ChatPromptTemplate.from_template(template=template, **config) type_to_loader_dict: dict[str, Callable[[dict], BasePromptTemplate]] = { "prompt": _load_prompt, "few_shot": _load_few_shot_prompt, "chat": _load_chat_prompt, }