Software engineering

Query string validation in Fastify

How to validate query parameters using Fastify

Bartosz Mikulski 25 Jan 2019 – 1 min read

What does the example of query string validation look in the Fastify documentation? Like this:

const schema = {
  querystring: {
    name: { type: 'string' },
    excitement: { type: 'integer' }
  }
}

What is the problem? It is a lie!

The correct way of defining the schema of query parameters in this case (two values: “name” and “excitement”). Looks like this:

const querySchema = {
    schema: {
       querystring: {
         type: 'object',
           properties: {
             name: {
               type: 'string'
             },
             excitement: {
               type: 'integer'
             },
         }
     }
  }
}

Additionally, if we want to make the name parameter mandatory, we add it to the array of required parameters:

const querySchema = {
    schema: {
       querystring: {
         type: 'object',
           properties: {
             name: {
               type: 'string'
             },
             excitement: {
               type: 'integer'
             },
         }
         required: ['name']
     }
  }
}