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)