Handle 'limit' event when file is over fileSize

[Haggus]

When 'limit' event fires, it returns 413 (Payload Too Large). Let me know if there is anything you'd like to do differently :)

This should close #40

[coveralls]

Coverage decreased (-2.0%) to 93.617% when pulling 10263ab on Haggus:handle-file-limit into c3c41ec on richardgirges:master.

[coveralls]

Coverage decreased (-2.0%) to 93.617% when pulling 10263ab on Haggus:handle-file-limit into c3c41ec on richardgirges:master.

[richardgirges]

Hi @Haggus thanks for the PR! It looks good - would you mind adding a unit test for this update?

Cheers

[coveralls]

Coverage increased (+2.3%) to 97.872% when pulling 91d944f on Haggus:handle-file-limit into c3c41ec on richardgirges:master.

[coveralls]

Coverage increased (+0.1%) to 95.745% when pulling 1c52f44 on Haggus:handle-file-limit into c3c41ec on richardgirges:master.

[Haggus]

Here you go! :)

[ShakMR]

Why not, instead of ending the request, adding some kind of attribute to the file (limitReached = true or truncated = true) to let us know so we can handle the error in our side?

What about something like this https://github.com/ShakMR/express-fileupload/blob/22a7d5cce1e8b857363543a04be8d3f6f671f130/lib/index.js#L76?
Complete list of changes here: https://github.com/ShakMR/express-fileupload/pull/1/files

[richardgirges]

I do like the idea of allowing the error to be handled by the user. What do you think @Haggus ?

@ShakMR since you already coded it, would you mind sending a PR?

I wonder if there would also be value in providing the user with either option. If we go with that, we can create a new configuration option and merge both solutions in.

[Haggus]

I think a configuration option to turn on automatic throw would be the best solution here.

Personally I prefer that the lib throws an error as soon as it hits the limit, but as @ShakMR mentioned, this might not be what everyone wants.

Also, when it comes to truncated flag, I think busboy may already have this implemented.

[tianjianchn]

Maybe trying these codes below:

.on('limit', () => {
  const err = new Error('Request Entity Too Large');
  err.statusCode = 413;
  next(err);
});

Since express can handle this error and respond right status code(413). and if user wants to handle that exception, he can use custom next function.
Hope it helps.