Server-Side Development with Fastify — Request Validation

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Fastify is a small Node framework for developing back end web apps.

In this article, we’ll look at how to create back end apps with Fastify.

Request Validation

We can specify how to validate requests with schema objects.

For example, we can write:

const fastify = require('fastify')({})
const bodyJsonSchema = {
  type: 'object',
  required: ['requiredKey'],
  properties: {
    someKey: { type: 'string' },
    someOtherKey: { type: 'number' },
    requiredKey: {
      type: 'array',
      maxItems: 3,
      items: { type: 'integer' }
    },
    nullableKey: { type: ['number', 'null'] },
    multipleTypesKey: { type: ['boolean', 'number'] },
    multipleRestrictedTypesKey: {
      oneOf: [
        { type: 'string', maxLength: 5 },
        { type: 'number', minimum: 10 }
      ]
    },
    enumKey: {
      type: 'string',
      enum: ['John', 'Foo']
    },
    notTypeKey: {
      not: { type: 'array' }
    }
  }
}
const queryStringJsonSchema = {
  type: 'object',
  properties: {
    name: { type: 'string' },
    excitement: { type: 'integer' }
  }
}
const paramsJsonSchema = {
  type: 'object',
  properties: {
    par1: { type: 'string' },
    par2: { type…