import copy
import json
from typing import Any, Dict, List, Optional, Type, Union
import jsonpatch
from langchain_core.exceptions import OutputParserException
from langchain_core.output_parsers import (
BaseCumulativeTransformOutputParser,
BaseGenerationOutputParser,
)
from langchain_core.output_parsers.json import parse_partial_json
from langchain_core.outputs import ChatGeneration, Generation
from langchain_core.pydantic_v1 import BaseModel, root_validator
[docs]class OutputFunctionsParser(BaseGenerationOutputParser[Any]):
"""Parse an output that is one of sets of values."""
args_only: bool = True
"""Whether to only return the arguments to the function call."""
[docs] def parse_result(self, result: List[Generation], *, partial: bool = False) -> Any:
generation = result[0]
if not isinstance(generation, ChatGeneration):
raise OutputParserException(
"This output parser can only be used with a chat generation."
)
message = generation.message
try:
func_call = copy.deepcopy(message.additional_kwargs["function_call"])
except KeyError as exc:
raise OutputParserException(f"Could not parse function call: {exc}")
if self.args_only:
return func_call["arguments"]
return func_call
[docs]class JsonOutputFunctionsParser(BaseCumulativeTransformOutputParser[Any]):
"""Parse an output as the Json object."""
strict: bool = False
"""Whether to allow non-JSON-compliant strings.
See: https://docs.python.org/3/library/json.html#encoders-and-decoders
Useful when the parsed output may include unicode characters or new lines.
"""
args_only: bool = True
"""Whether to only return the arguments to the function call."""
@property
def _type(self) -> str:
return "json_functions"
def _diff(self, prev: Optional[Any], next: Any) -> Any:
return jsonpatch.make_patch(prev, next).patch
[docs] def parse_result(self, result: List[Generation], *, partial: bool = False) -> Any:
if len(result) != 1:
raise OutputParserException(
f"Expected exactly one result, but got {len(result)}"
)
generation = result[0]
if not isinstance(generation, ChatGeneration):
raise OutputParserException(
"This output parser can only be used with a chat generation."
)
message = generation.message
try:
function_call = message.additional_kwargs["function_call"]
except KeyError as exc:
if partial:
return None
else:
raise OutputParserException(f"Could not parse function call: {exc}")
try:
if partial:
try:
if self.args_only:
return parse_partial_json(
function_call["arguments"], strict=self.strict
)
else:
return {
**function_call,
"arguments": parse_partial_json(
function_call["arguments"], strict=self.strict
),
}
except json.JSONDecodeError:
return None
else:
if self.args_only:
try:
return json.loads(
function_call["arguments"], strict=self.strict
)
except (json.JSONDecodeError, TypeError) as exc:
raise OutputParserException(
f"Could not parse function call data: {exc}"
)
else:
try:
return {
**function_call,
"arguments": json.loads(
function_call["arguments"], strict=self.strict
),
}
except (json.JSONDecodeError, TypeError) as exc:
raise OutputParserException(
f"Could not parse function call data: {exc}"
)
except KeyError:
return None
# This method would be called by the default implementation of `parse_result`
# but we're overriding that method so it's not needed.
[docs] def parse(self, text: str) -> Any:
raise NotImplementedError()
[docs]class JsonKeyOutputFunctionsParser(JsonOutputFunctionsParser):
"""Parse an output as the element of the Json object."""
key_name: str
"""The name of the key to return."""
[docs] def parse_result(self, result: List[Generation], *, partial: bool = False) -> Any:
res = super().parse_result(result, partial=partial)
if partial and res is None:
return None
return res.get(self.key_name) if partial else res[self.key_name]
[docs]class PydanticOutputFunctionsParser(OutputFunctionsParser):
"""Parse an output as a pydantic object.
This parser is used to parse the output of a ChatModel that uses
OpenAI function format to invoke functions.
The parser extracts the function call invocation and matches
them to the pydantic schema provided.
An exception will be raised if the function call does not match
the provided schema.
Example:
... code-block:: python
message = AIMessage(
content="This is a test message",
additional_kwargs={
"function_call": {
"name": "cookie",
"arguments": json.dumps({"name": "value", "age": 10}),
}
},
)
chat_generation = ChatGeneration(message=message)
class Cookie(BaseModel):
name: str
age: int
class Dog(BaseModel):
species: str
# Full output
parser = PydanticOutputFunctionsParser(
pydantic_schema={"cookie": Cookie, "dog": Dog}
)
result = parser.parse_result([chat_generation])
"""
pydantic_schema: Union[Type[BaseModel], Dict[str, Type[BaseModel]]]
"""The pydantic schema to parse the output with.
If multiple schemas are provided, then the function name will be used to
determine which schema to use.
"""
@root_validator(pre=True)
def validate_schema(cls, values: Dict) -> Dict:
schema = values["pydantic_schema"]
if "args_only" not in values:
values["args_only"] = isinstance(schema, type) and issubclass(
schema, BaseModel
)
elif values["args_only"] and isinstance(schema, Dict):
raise ValueError(
"If multiple pydantic schemas are provided then args_only should be"
" False."
)
return values
[docs] def parse_result(self, result: List[Generation], *, partial: bool = False) -> Any:
_result = super().parse_result(result)
if self.args_only:
pydantic_args = self.pydantic_schema.parse_raw(_result) # type: ignore
else:
fn_name = _result["name"]
_args = _result["arguments"]
pydantic_args = self.pydantic_schema[fn_name].parse_raw(_args) # type: ignore # noqa: E501
return pydantic_args
[docs]class PydanticAttrOutputFunctionsParser(PydanticOutputFunctionsParser):
"""Parse an output as an attribute of a pydantic object."""
attr_name: str
"""The name of the attribute to return."""
[docs] def parse_result(self, result: List[Generation], *, partial: bool = False) -> Any:
result = super().parse_result(result)
return getattr(result, self.attr_name)