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<h1 align="center">Fastify</h1>
## Fluent Schema
The [Validation and
Serialization](../Reference/Validation-and-Serialization.md) documentation
outlines all parameters accepted by Fastify to set up JSON Schema Validation to
validate the input, and JSON Schema Serialization to optimize the output.
[`fluent-json-schema`](https://github.com/fastify/fluent-json-schema) can be
used to simplify this task while allowing the reuse of constants.
### Basic settings
```js
const S = require('fluent-json-schema')
// You can have an object like this, or query a DB to get the values
const MY_KEYS = {
KEY1: 'ONE',
KEY2: 'TWO'
}
const bodyJsonSchema = S.object()
.prop('someKey', S.string())
.prop('someOtherKey', S.number())
.prop('requiredKey', S.array().maxItems(3).items(S.integer()).required())
.prop('nullableKey', S.mixed([S.TYPES.NUMBER, S.TYPES.NULL]))
.prop('multipleTypesKey', S.mixed([S.TYPES.BOOLEAN, S.TYPES.NUMBER]))
.prop('multipleRestrictedTypesKey', S.oneOf([S.string().maxLength(5), S.number().minimum(10)]))
.prop('enumKey', S.enum(Object.values(MY_KEYS)))
.prop('notTypeKey', S.not(S.array()))
const queryStringJsonSchema = S.object()
.prop('name', S.string())
.prop('excitement', S.integer())
const paramsJsonSchema = S.object()
.prop('par1', S.string())
.prop('par2', S.integer())
const headersJsonSchema = S.object()
.prop('x-foo', S.string().required())
// Note that there is no need to call `.valueOf()`!
const schema = {
body: bodyJsonSchema,
querystring: queryStringJsonSchema, // (or) query: queryStringJsonSchema
params: paramsJsonSchema,
headers: headersJsonSchema
}
fastify.post('/the/url', { schema }, handler)
```
### Reuse
With `fluent-json-schema`, you can manipulate your schemas more easily and
programmatically and then reuse them thanks to the `addSchema()` method. You can
refer to the schema in two different manners that are detailed in the
[Validation and
Serialization](../Reference/Validation-and-Serialization.md#adding-a-shared-schema)
documentation.
Here are some usage examples:
**`$ref-way`**: refer to an external schema.
```js
const addressSchema = S.object()
.id('#address')
.prop('line1').required()
.prop('line2')
.prop('country').required()
.prop('city').required()
.prop('zipcode').required()
const commonSchemas = S.object()
.id('https://fastify/demo')
.definition('addressSchema', addressSchema)
.definition('otherSchema', otherSchema) // You can add any schemas you need
fastify.addSchema(commonSchemas)
const bodyJsonSchema = S.object()
.prop('residence', S.ref('https://fastify/demo#address')).required()
.prop('office', S.ref('https://fastify/demo#/definitions/addressSchema')).required()
const schema = { body: bodyJsonSchema }
fastify.post('/the/url', { schema }, handler)
```
**`replace-way`**: refer to a shared schema to replace before the validation
process.
```js
const sharedAddressSchema = {
$id: 'sharedAddress',
type: 'object',
required: ['line1', 'country', 'city', 'zipcode'],
properties: {
line1: { type: 'string' },
line2: { type: 'string' },
country: { type: 'string' },
city: { type: 'string' },
zipcode: { type: 'string' }
}
}
fastify.addSchema(sharedAddressSchema)
const bodyJsonSchema = {
type: 'object',
properties: {
vacation: 'sharedAddress#'
}
}
const schema = { body: bodyJsonSchema }
fastify.post('/the/url', { schema }, handler)
```
> ℹ️ Note:
> You can mix up the `$ref-way` and the `replace-way`
> when using `fastify.addSchema`.