# StringEvaluator

> **Class** in `langsmith`

📖 [View in docs](https://reference.langchain.com/python/langsmith/evaluation/string_evaluator/StringEvaluator)

Grades the run's string input, output, and optional answer.

.. deprecated:: 0.5.0

   StringEvaluator is deprecated. Use openevals instead: https://github.com/langchain-ai/openevals

## Signature

```python
StringEvaluator()
```

## Extends

- `RunEvaluator`
- `BaseModel`

## Properties

- `evaluation_name`
- `input_key`
- `prediction_key`
- `answer_key`
- `grading_function`

## Methods

- [`evaluate_run()`](https://reference.langchain.com/python/langsmith/evaluation/string_evaluator/StringEvaluator/evaluate_run)

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[View source on GitHub](https://github.com/langchain-ai/langsmith-sdk/blob/19dc497a3d89638e4cc35db72ea1c29cad35cbbf/python/langsmith/evaluation/string_evaluator.py#L12)