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# getClassifier()

The `getClassifier()` method retrieves a classifier that was registered with the Mastra instance using its registration key. It throws an error if the requested classifier isn't found.

## Usage example

```typescript
import { mastra } from './mastra'

const safety = mastra.getClassifier('safety')

const result = await safety.evaluate({
  state: { content: 'A message to evaluate' },
})
```

## Parameters

**key** (`string`): The registration key of the classifier to retrieve. This should match a key used when registering classifiers in the Mastra constructor.

## Returns

**classifier** (`Classifier`): The Classifier instance associated with the provided key.

## Error handling

This method throws a `MastraError` with id `MASTRA_GET_CLASSIFIER_NOT_FOUND` if no classifier is registered under the specified key.

## Related

- [getClassifierById()](https://mastra.ai/reference/core/getClassifierById): Get a classifier by its id property
- [listClassifiers()](https://mastra.ai/reference/core/listClassifiers): Get all registered classifiers
- [Classifier](https://mastra.ai/reference/classifier/classifier)