Route middleware

[R5dan]

Goals

1. Get a variable / run some code for a group of routes

Background

Reduces code duplication. I have a app, with the first four lines of 1/3 of my api endpoints are:

const user = auth(req)
if (!user) {
    return Response.json(..., {status: 401})
}

This could all go into a file at the base route of all of these and execute every time.
Another example is with dynamic route segments. Say you have a dynamic segment called [id] and for every route beyond that you want to get some data from a database based solely on that id (user etc). This could be fetched at the base of this dynamic segment to fetch the data and give it to the route handler.

Proposal

Have a file called something (I don't care what it is called). This file can have the following exports:

default: Runs on every request (for routes beyond it)
METHOD: Runs on every request with that method (useful for api routes)

This functions inside this file can return two things:

• Response: This response is sent to the client immediately (can be jsx for page.ts)
• An object containing variables: these variables get sent to the route handler

These functions are always run on the server, and parsed all variables the route handler would.