Add RFC7231 Accept header parsing

[ekroon]

I would like to use ROAPI endpoints from a browser. Currently when accessing /api/tables/{table_name} endpoint with a browser you get an error like the following:

{ "code": 400, "error": "unsupported_content_type", "message": "\"text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9\" is not a supported response content type" }

How to parse the Accept header is specified in RFC7231 and Actix has an implementation for this. How to implement this would be impacted by #76 and if this would be implemented it might make switching harder.

An easy quicfix would be to implement a fallback to application/json if the resulting content-type is unknown.

[houqp]

Good catch @ekroon , did you mean to access the endpoint by loading it directly in a browser or loading it through AJAX call?

Regardless, I agree with you that we should support q factor weighting in request header parsing. I think a fallback to json makes sense when accept header is not specified at all by the client. Otherwise, it might confuse the client.

[ekroon]

I mean loading it directly in the browser window.

[houqp]

Got it, extending on your use-case, I think it might be an interesting idea to implement a html or xml encoding type. The html encoding could render the query result in a nicely looking web page to help better visualize the result. We can even throw in some js code to make the resulting web page interactive.

[xezpeleta]

Hi, I agree with @ekroon

A fallback to application/json would be enough.

Thanks!!

[ekroon]

A full implementation for Accept header parsing will be a bit involved as there is no implementation available for Axum. The correct place to implement this would be hyperium/headers#7 but that appears to be a little bit stalled. Maybe a port of Rocket or Actix's implementation in a separate crate is a quicker solution.

Alternatively, supporting the format in the url extension, like .json, .csv, would be an easy usable solution from browsers too. This would work nicely with a future .html version.

[houqp]

Thanks @ekroon , I agree with both of your points :) For your first point, on top of what's in rocket and actix, I think we can also take hyperium/headers#70 as a reference to build out the crate.