Source code for langchain_core.prompts.loading
"""Load prompts."""
import json
import logging
from pathlib import Path
from typing import Callable, Dict, 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:
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 = 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:
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:
# https://github.com/langchain-ai/langchain/issues/4394
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], 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://"):
raise RuntimeError(
"Loading from the deprecated github-based Hub is no longer supported. "
"Please use the new LangChain Hub at https://smith.langchain.com/hub "
"instead."
)
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.
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, encoding=encoding) as f:
config = json.load(f)
elif file_path.suffix.endswith((".yaml", ".yml")):
with open(file_path, mode="r", encoding=encoding) 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,
}
