alphaNum
Validates the value to only have letters, numeric or both of them. The validation rule only works with the string schema
type.
import { schema, rules } from '@ioc:Adonis/Core/Validator'
{
  username: schema.string([
    rules.alphaNum(),
  ])
}
You can also allow the string to have spaces, dash and underscore characters.
{
  username: schema.string([
    rules.alphaNum({
      allow: ['space', 'underscore', 'dash']
    })
  ])
}