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https://github.com/eomm/fastify-schema-constraint
Choose the right JSON schema to apply to your routes based on your constraints
https://github.com/eomm/fastify-schema-constraint
fastify fastify-plugin json-schema
Last synced: about 2 months ago
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Choose the right JSON schema to apply to your routes based on your constraints
- Host: GitHub
- URL: https://github.com/eomm/fastify-schema-constraint
- Owner: Eomm
- License: mit
- Created: 2019-03-13T17:44:29.000Z (almost 6 years ago)
- Default Branch: main
- Last Pushed: 2024-08-19T10:38:09.000Z (4 months ago)
- Last Synced: 2024-10-30T10:22:22.033Z (about 2 months ago)
- Topics: fastify, fastify-plugin, json-schema
- Language: JavaScript
- Size: 23.4 KB
- Stars: 13
- Watchers: 3
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# fastify-schema-constraint
[](https://github.com/Eomm/fastify-schema-constraint/actions)
[](https://www.npmjs.com/package/fastify-schema-constraint)
[](https://standardjs.com)
Choose the right JSON schema to apply to your routes based on your constraints.
With this plugin, you will be able to set multiple schemas per `route` and, programmatically,
choose which one applies.
Ex: you can choose which JSON schema to apply, based on the `req.headers` values.
## Install
```
npm install fastify-schema-constraint
```
### Compatibility
| Plugin version | Fastify version |
| ------------- |:---------------:|
| `^1.0.0` | `^2.0.0` |
| `^2.0.0` | `^3.0.0` |
| `^3.0.0` | `^4.0.0` |
## Usage
This plugin will act on `preHandler` hook and will verify if the payload of the `body`, `querystring`,
`params` or `headers` fulfil the constraint condition.
```js
// Define the set of your JSON Schema. They MUST be in an array assigned to `oneOf` property
const routeSchema = {
oneOf: [
{ $id: '#schema1', type: 'object', properties: { mul5: { type: 'number', multipleOf: 5 } } },
{ $id: '#schema2', type: 'object', properties: { mul3: { type: 'number', multipleOf: 3 } } },
{ $id: '#schema3', type: 'object', properties: { mul2: { type: 'number', multipleOf: 2 } } }
]
}
// Define your constraint logic
const constraint = {
body: {
constraint: function (request) {
switch(request.headers.myHeader){
case 1: return '#schema1'
case 2: return '#schema3'
case 3: return '#schema2'
default: return null // it means "don't apply any constraint"
}
},
statusCode: 412, // Optionally define a custom status code in case of errors
errorMessage: 'This constraint return only #schema1' // Optionally define a custom error message
},
querystring: { ... },
params: { ... },
headers: { ... }
}
const fastify = Fastify()
fastify.register(require('fastify-schema-constraint'), constraint)
fastify.route({
url: '/:mul5',
method: 'POST',
handler: (_, reply) => { reply.send('hi') },
schema: {
body: routeSchema,
querystring: routeSchema,
params: routeSchema,
headers: routeSchema
}
})
```
### Options
The options accept a json in this format:
```js
const constraint = {
body: { ... }, // constraint to apply on body
querystring: { ... }, // constraint to apply on query string
params: { ... }, // constraint to apply on path parameters
headers: { ... } // constraint to apply on headers
}
```
All the fields are optional, but you must provide **almost one** of these settings.
If you provide a constraint for `body`, but the route doesn't have any schema configured
the plugin will skip the constraint.
Each constraint field accepts a json in this format:
```js
{
constraint: function (request) {
// This field is mandatory and must be set with a function.
// The input paramenter is the Fastify request.
// This function must be sync and must return a string with the JSON Schema $id to constraint
return '#idToApply'
},
statusCode: 412, // Optionally: set a custom status code in case of errors, default 400
errorMessage: 'This constraint return only #idToApply' // Optionally: set a custom error message
}
```
**NB:**
+ if the constraint function returns something different than a string, the validation will be skipped!
+ if the constraint function throws an error, an error will be thrown
+ if the returned `$id` isn't present in the `oneOf` array an error will be thrown
+ if the payload verified doesn't match with the returned `$id`, an error will be thrown
## License
Copyright [Manuel Spigolon](https://github.com/Eomm), Licensed under [MIT](./LICENSE).