Add a "layout" for endpoints

Describe the problem

If I currently have an endpoint that should only be available for logged in users. I can do the following:

export async function get({ locals }) {
  if (!locals.user) {
    return {
      status: 401
    }
  }
   // otherwise proceed and return the data
  return {
    status: 200,
    body: data
  }
}

This works fine, but in some cases can be a bit of a hassle, especially if there are several endpoints and this code has to be copied in all these files.

Describe the proposed solution

Similar to __layout.svelte a new file named __layout.js that runs before the actual endpoints, this allows the developer to group all these access checks in one place. With the fall through rule we already have in place it would mean the above code would be in this new file and not have to be repeated.

export async function get({ locals }) {
  if (!locals.user) {
    return {
      status: 401
    }
 }

 // No return value as we want the normal endpoints to kick in.
}

Alternatives considered

Copying the testing logic to a shared function also works, But this is not much shorter as we still have to construct and return the return object.

Importance

would make my life easier

Additional Information

No response

[kevmodrome]

I think this sounds like a neat idea. I’d probably lean towards calling it something like __middleware though.

[jchanes04]

I agree that adding a feature like this would help to reduce the amount of repeated code and improve readability. Perhaps the name __pre.js could be used for this, as this code would run before the request is passed on to the endpoints. __layout.js doesn’t make much sense, since endpoints are usually not responsible for returning HTML and this code would not “append” anything to what was returned from the endpoint like __layout.svelte does.