Schema

One of the most important areas to create a secure web server is to make sure that requests are in the correct shape.

Elysia handled this by providing a validation tool out of the box to validate incoming requests using Schema Builder.

Elysia.t, a schema builder based on TypeBox to validate the value in both runtime and compile-time, providing type safety like in a strict type language.

Type

Elysia schema can validate the following:

• body - HTTP body.
• query - query string or URL parameters.
• params - Path parameters.
• header - Request's headers.
• cookie - Request's cookie
• response - Value returned from handler

Schema can be categorized into 2 types:

1. Local Schema: Validate on a specific route
2. Global Schema: Validate on every route

Local Schema

The local schema is executed on a specific route.

To validate a local schema, you can inline schema into a route handler:

import { Elysia, t } from 'elysia'

new Elysia()
    .get('/id/:id', ({ params: { id } }) => id, {
        params: t.Object({ 
            id: t.Numeric() 
        }) 
    })
    .listen(3000)

localhost/id/1/id/a

GET

This code ensures that our path parameter id, will always be a numeric string and then transform to a number automatically in both runtime and compile-time (type-level).

The response should be listed as follows:

Path	Response
/id/1	1
/id/a	Error

Global Schema

Register hook into every handler that came after.

To add a global hook, you can use .guard followed by a life cycle event in camelCase:

import { Elysia, t } from 'elysia'

new Elysia()
    .get('/none', () => 'hi')
    .guard({ 
        query: t.Object({ 
            name: t.String() 
        }) 
    }) 
    .get('/query', ({ query: { name } }) => name)
    .get('/any', ({ query }) => query)
    .listen(3000)

This code ensures that the query must have name with a string value for every handler after it. The response should be listed as follows:

localhost/none/query/any

GET

The response should be listed as follows:

Path	Response
/none	hi
/none?name=a	hi
/query	error
/query?name=a	a

If multiple global schemas are defined for same property, the latest one will have the preference. If both local and global schemas are defined, the local one will have the preference.