@fastify/response-validation
v3.0.2
Published
A simple plugin that enables response validation for Fastify.
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@fastify/response-validation
A simple plugin that enables response validation for Fastify. The use of this plugin will slow down your overall performance, so we suggest using it only during development.
Install
npm i @fastify/response-validation
Usage
You just need to register the plugin and you will have response validation enabled:
import fastify from 'fastify'
const app = fastify()
await app.register(require('@fastify/response-validation'))
app.route({
method: 'GET',
path: '/',
schema: {
response: {
'2xx': {
type: 'object',
properties: {
answer: { type: 'number' }
}
}
}
},
handler: async (req, reply) => {
return { answer: '42' }
}
})
app.inject({
method: 'GET',
path: '/'
}, (err, res) => {
if (err) throw err
console.log(res.payload)
})
Different content types responses are supported by @fastify/response-validation
, @fastify/swagger
and fastify
. Please use content
for the response otherwise Fastify itself will fail to compile the schema:
{
response: {
200: {
description: 'Description and all status-code based properties are working',
content: {
'application/json': {
schema: {
name: { type: 'string' },
image: { type: 'string' },
address: { type: 'string' }
}
},
'application/vnd.v1+json': {
schema: {
fullName: { type: 'string' },
phone: { type: 'string' }
}
}
}
}
}
}
If you want to override the default ajv configuration, you can do that by using the ajv
option:
// Default configuration:
// coerceTypes: false
// useDefaults: true
// removeAdditional: true
// allErrors: true
import responseValidator from '@fastify/response-validation'
// ... App setup
await fastify.register(responseValidator, {
ajv: {
coerceTypes: true
}
})
You can also pass in an instance of ajv
// Default configuration:
// coerceTypes: false
// useDefaults: true
// removeAdditional: true
// allErrors: true
import responseValidator from '@fastify/response-validation'
import Ajv from 'ajv'
// ... App setup
const ajv = new Ajv()
await fastify.register(responseValidator, { ajv })
By default the response validation is enabled on every route that has a response schema defined. If needed you can disable it all together with responseValidation: false
:
import responseValidator from '@fastify/response-validation'
// ... App setup
await fastify.register(responseValidator, {
responseValidation: false
})
Alternatively, you can disable a specific route with the same option:
fastify.route({
method: 'GET',
path: '/',
responseValidation: false,
schema: {
response: {
'2xx': {
type: 'object',
properties: {
answer: { type: 'number' }
}
}
}
},
handler: async (req, reply) => {
return { answer: '42' }
}
})
Plugins
You can also extend the functionalities of the ajv instance embedded in this validator by adding new ajv plugins.
fastify.register(require('fastify-response-validation'), {
ajv: {
plugins: [
require('ajv-formats'),
[require('ajv-errors'), { singleError: false }]
// Usage: [plugin, pluginOptions] - Plugin with options
// Usage: plugin - Plugin without options
]
}
})
Errors
The errors emitted by this plugin are:
FST_RESPONSE_VALIDATION_FAILED_VALIDATION
: This error is emitted when a response does not conform to the provided schema.FST_RESPONSE_VALIDATION_SCHEMA_NOT_DEFINED
: This error is emitted when there is no JSON schema available to validate the response.