Source code for langchain_core.prompts.loading

"""Load prompts."""

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

import yaml

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

logger = logging.getLogger(__name__)

[docs]def load_prompt_from_config(config: dict) -> BasePromptTemplate: """Load prompt from Config Dict.""" 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: raise ValueError(f"Loading {config_type} prompt not supported") 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: raise ValueError( f"Both `{var_name}_path` and `{var_name}` cannot be provided." ) # 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 = 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: raise ValueError( "Invalid file format. Only json or yaml formats are supported." ) config["examples"] = examples else: raise ValueError("Invalid examples format. Only list or string are supported.") 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: raise ValueError(f"Unsupported output parser {output_parser_type}") 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: raise ValueError( "Only one of example_prompt and example_prompt_path should " "be specified." ) 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: # raise ValueError( 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." ) return PromptTemplate(**config)
[docs]def load_prompt(path: Union[str, Path]) -> BasePromptTemplate: """Unified method for loading a prompt from LangChainHub or local fs.""" if isinstance(path, str) and path.startswith("lc://"): raise RuntimeError( "Loading from the deprecated github-based Hub is no longer supported. " "Please use the new LangChain Hub at " "instead." ) return _load_prompt_from_file(path)
def _load_prompt_from_file(file: Union[str, Path]) -> BasePromptTemplate: """Load prompt from file.""" # Convert file to a Path object. if isinstance(file, str): file_path = Path(file) else: file_path = file # Load from either json or yaml. if file_path.suffix == ".json": with open(file_path) as f: config = json.load(f) elif file_path.suffix.endswith((".yaml", ".yml")): with open(file_path, "r") as f: config = yaml.safe_load(f) else: raise ValueError(f"Got unsupported file type {file_path.suffix}") # 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: raise ValueError("Can't load chat prompt without template") 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, }