Source code for langchain.evaluation.parsing.json_schema
from typing import Any, Union
from langchain_core.utils.json import parse_json_markdown
from langchain.evaluation.schema import StringEvaluator
[docs]
class JsonSchemaEvaluator(StringEvaluator):
"""An evaluator that validates a JSON prediction against a JSON schema reference.
This evaluator checks if a given JSON prediction conforms to the provided JSON schema.
If the prediction is valid, the score is True (no errors). Otherwise, the score is False (error occurred).
Attributes:
requires_input (bool): Whether the evaluator requires input.
requires_reference (bool): Whether the evaluator requires reference.
evaluation_name (str): The name of the evaluation.
Examples:
evaluator = JsonSchemaEvaluator()
result = evaluator.evaluate_strings(
prediction='{"name": "John", "age": 30}',
reference={
"type": "object",
"properties": {
"name": {"type": "string"},
"age": {"type": "integer"}
}
}
)
assert result["score"] is not None
""" # noqa: E501
[docs]
def __init__(self, **kwargs: Any) -> None:
"""Initializes the JsonSchemaEvaluator.
Args:
kwargs: Additional keyword arguments.
Raises:
ImportError: If the jsonschema package is not installed.
"""
super().__init__()
try:
import jsonschema # noqa: F401
except ImportError:
raise ImportError(
"The JsonSchemaEvaluator requires the jsonschema package."
" Please install it with `pip install jsonschema`."
)
@property
def requires_input(self) -> bool:
"""Returns whether the evaluator requires input."""
return False
@property
def requires_reference(self) -> bool:
"""Returns whether the evaluator requires reference."""
return True
@property
def evaluation_name(self) -> str:
"""Returns the name of the evaluation."""
return "json_schema_validation"
def _parse_json(self, node: Any) -> Union[dict, list, None, float, bool, int, str]:
if isinstance(node, str):
return parse_json_markdown(node)
elif hasattr(node, "schema") and callable(getattr(node, "schema")):
# Pydantic model
return getattr(node, "schema")()
return node
def _validate(self, prediction: Any, schema: Any) -> dict:
from jsonschema import ValidationError, validate
try:
validate(instance=prediction, schema=schema)
return {
"score": True,
}
except ValidationError as e:
return {"score": False, "reasoning": repr(e)}
def _evaluate_strings(
self,
prediction: Union[str, Any],
input: Union[str, Any] = None,
reference: Union[str, Any] = None,
**kwargs: Any,
) -> dict:
parsed_prediction = self._parse_json(prediction)
schema = self._parse_json(reference)
return self._validate(parsed_prediction, schema)