Customizing the validator compiler

Fastify exposes a lot of options to provide a flexible validation process and complete control of it. We are going to explore all the possible customizations one by one, so you will be a validator compiler guru by the end of this section! Let’s jump into this journey one step at a time!

Flow control

In the previous section, we mentioned the attachValidation route option – it’s time to look at an example (although you probably already know how to use it, thanks to the previous chapters):

app.get('/attach-validation', {
  attachValidation: true,
  schema: {
    headers: jsonSchemaHeaders
  },
  handler: (request, reply) => {
    reply.send(request.validationError)
  }
})

Adding the flag into the route option will prevent a validation error from being thrown. Instead, the validation execution process will be interrupted...