Fastify - Number validator example

routes.js

module.exports = [{
  method : 'GET',
  url : '/checkNumbers',
  handler : async (req, reply) => ({ message : 'Yay! Success!, success : true }),
  schema : {
    querystring : {
      type : 'object',
      properties : {
        positive_number : { 
          type : 'number', 
          validator : [(data) => data > 0, _ => 'must be positive number'],
        },
        negative_number : { 
          type : 'number',
          validator : (data) => data < 0, // will use default message
        },
      },
      required: ['positive_number', 'negative_number'],
    },
  }
}]