# `mix ash.gen.validation`
[🔗](https://github.com/ash-project/ash/blob/v3.23.1/lib/mix/tasks/gen/ash.gen.validation.ex#L6)

Generates a custom validation

See [Custom Validations](https://hexdocs.pm/ash/validations.html#custom-validations) for more.

## Example

```bash
mix ash.gen.validation MyApp.Validations.IsPrime
```

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*Consult [api-reference.md](api-reference.md) for complete listing*