Better error handling

[mimol91]

I am using traverson for a while.
Recently I've noticed that there is no way to detect if error during request is from traverson or traverson-hal. Moreover it returns only plain message, without any error type.
Like in https://github.com/basti1302/traverson-hal/blob/master/index.js#L64
I need to know if its a linkError or embeddedError (For example link to resource is not in server response)
Currently I can only parse strings, but it would be much more convenient to get error type, either by
create own Error types,
pass to Error object instead string
or just add ctx as 2nd argument of Error

[basti1302]

This sounds like a good idea. However, I'd like to really understand your use case and the requirements here. Could you paste a code snippet of the part where you are using traverson/traverson-hal. You probably have some kind of if statement that does different things depending on the kind of error, I would like to see that, if possible.

[mimol91]

Hey.
Thanks for response.

It is taken form Traverson Readme

  traverson
    .from('http://api.io')
    .jsonHal()
    .follow('ht:me', 'ht:posts')
    .getResource(function(error, document) {
      if (error) {
        console.error(error.name)
      }
    });

I can get error type - which is JSONError
https://github.com/basti1302/traverson/blob/0fd4f349e2bf007ea8440284e3e1e252f08e7ae1/lib/transforms/parse.js - so its really great.

I've also tried

  traverson
    .from('http://haltalk.herokuapp.com/')
    .jsonHal()
    .follow('ht:me')
    .getResource(function(error, document) {
      if (error) {
        console.log(error.name);
      }
    });

error.name - HTTPError, becauses erver status code = 500

The problem is with

  traverson
    .from('http://api.opensupporter.org/api/v1/')
    .jsonHal()
    .follow('self', 'invalid_link')
    .getResource(function(error, document) {
      if (error) {
        console.log(error.name);
      }
    });

error.name is just 'error' https://github.com/basti1302/traverson-hal/blob/master/index.js#L64

I would like to know what type of error it is. (like linkMissing), and some other errors for ctx.linkError or ctx.embeddedError.
I need to be able to detect if there is no link which I want to traverse (invalid_link) in server response

[basti1302]

Thanks for the code snippets. That's not exactly what I meant, though. What I am interested in is what you are going to do, depending on various error types. How does you code handle these different errors? You surely do not want to differentiate between them just to call console.log right?

[mimol91]

Sure.
Basically I want to distinguish at least to types:

• When server status code >= 300 I want to display modal which says that something goes wrong and user need to refresh page
• If link is missing, I need to catch it and set result as empty array (I m using redux, and API do not return link if collection is empty)

[mimol91]

@basti1302 Should I prepare PR for that?

[basti1302]

Yes, that would be welcome!

[mimol91]

@basti1302
Could you do CodeReview for #22 ?

[basti1302]

Sure, I'll probably can get it done tomorrow. A little more patience :)

[mimol91]

Thanks for merging.
I will close this issue,

[basti1302]

This has been released with version 5.0.0.

[basti1302]

From the release notes, for reference: All Error objects created by Traverson and traverson-hal now have the name property set, see Traverson API docs on error names and traverson-hal docs on error names. (#21 and #22, thanks to @mimol91)

[basti1302]

Btw, thanks for the PR over in #22 and bringing the issue up in general. After merging your changes I extended them to the whole codebase. You might want to check out this commit in traverson-hal and this commit in traverson to see if it still fits your requirements (it should, I think).

Also, this comment might be relevant for your use case (depends on your hal documents).