Midwest Responder
One of the main concepts behind Midwest is a global responder middleware.
Basically no other middleware should be sending the response, they should
simply call next() until the responder is reached. The responder then either
send the contents of res.locals as JSON or renders a template.
Only the global responder should ever be terminating a request (ie. send a response).
The responder is a very short and simple middleware that decides what to send back to the client.
Usage
const errorHandler = require('@midwest/error-handler')(config.errorHandler)
server.use([
require('midwest/middleware/ensure-found'),
// format and log error
errorHandler,
// respond
require('@midwest/responder')({
errorHandler,
logError: require('@midwest/error-handler/log'),
}),
])Rendering
When the responder renders, calls the the render method:
res.render(res.master, ...(res.templates || []))Master vs Template
The master is the template that contains the <html>, <head> and <body> tags. It includes
scripts, styles etc.
Prevent Flattening
If there is only a single property on the res.locals object,
the responder will send that property directly. Ie. if res.locals = { poopsicle: {...} }
{...} will be sent instead of { poopsicle: {...} }.
Caveats
Static routes also matching dynamic routes
Since no middleware except the responder should be sending the response, dynamic routes that match static routes will clash.
Ie. if you have
server.get('/api/users/me', mw.getCurrent)
server.get('/api/users/:id', isAdmin, mw.findById)and make a request to /api/users/me, the isAdmin
and mw.findById middleware will always be called after mw.getCurrent.
If the user is not an admin, all requests to /api/users/me will return
the 401 response from isAdmin middleware.
To prevent this, create a Express#param function like so:
router.param(':id', (req, res, next, id) => {
if (id === 'me')
return next('route')
next()
})