[fature idea] Hook: withCustomError

[ghsamm]

Hello guys,

I'm submitting the basic idea here and once you approve it, I'll add the PR with types and tests et al.

The hook is called withCustomError and it can be used to change errors thrown by other hooks.

The scenario goes like this: I want to use the disable hook but return a 404 NotFound error instead of the default MethodNotAllowed error.

Basically, instead of writing the following e.g:

disallow("external") // throws MethodNotAllowed

We would wrap it in a withCustomError utility hook, like so:

withCustomError(disallow("extenral"), () => new NotFound()) // throws NotFound

The basic code goes like this:

const withCustomError = (hook, errorCreator) => (context: any) => {
  try {
   // if the hook does not produce an error, no need to throw
    const res = hook(context);
    return res;
  } catch (err) {
    throw errorCreator(context);
  }
};

We can also use function composition to create a new disallow404 like so:

const disallow404 = (...providers) => withCustomError(disallow(...providers), () => new NotFound());

What do you think ?

[1valdis]

That would definitely be useful if an error needs to be, for example, localized.

[michaelwiles]

+1

[michaelwiles]

For the record, in case anyone else copies this, an await is required before the call to the internal hook.

const withCustomError = (hook, errorCreator) => (context: any) => {
  try {
   // if the hook does not produce an error, no need to throw
    const res = await hook(context);
    return res;
  } catch (err) {
    throw errorCreator(context);
  }
};

[fratzinger]

Thanks for the suggestion and sorry for the late response. I started working on a massive rewrite of the package (#764). It's not released yet and will take a few weeks.

This should be working then. I took a more drastical approach. I introduced a new hook called throwIfIsProvider which basically works the same as disallow but has a more clear naming and has an error option to change the error, see https://github.com/feathersjs-ecosystem/feathers-hooks-common/blob/modernize/src/hooks/throw-if/throw-if-is-provider.ts