Handle Missing Data
👨💼 One of our Quality Assurance folks discovered an issue. If you go to a user
that does not exist, the app crashes. For example,
try this one: 😬
We had to ignore some TypeScript errors with
// @ts-expect-error which should
have tipped us off about this problem... 🦺 Lily the life jacket is not amused.We need to handle this case. That should be a
404 error. So after trying to
get the user from the database, you're going to need to check whether the
returned user exists. If they don't, then you should throw a 404 error.
Here's an example how you do that:export async function loader({ params }) {
const sandwich = await db.sandwich.findFirst({
where: { id: params.id },
})
if (!sandwich) {
throw new Response('Sandwich not found', { status: 404 })
}
return json({ sandwich })
}
Hmmm...
throw a response!? How weird is that? Well, in Remix it's exactly how
you solve this problem. It allows you to easily exit code flow and send a
response right away. You can even put it into a utility function:function assertDefined<Value>(
value: Value | null | undefined,
): asserts value is Value {
if (value === undefined || value === null) {
throw new Response('Not found', { status: 404 })
}
}
export async function loader({ params }) {
const sandwich = await db.sandwich.findFirst({
where: { id: params.id },
})
assertDefined(sandwich)
return json({ sandwich })
}
Remix will handle catching the response for us and send the response we threw
along. But it does so in a special way which we'll get to in a future exercise.
For now, just handling the error with a proper status code is enough.
So please handle possible missing data in the loaders of the profile, note list,
and note routes.