Issue with returning a TJsonObject about mars HOT 6 CLOSED

Hi Andrea,

I think there may be a bug with the MARS.JsonDataObjects.ReadersAndWriters where it doesn't use a "fallback" encoding.

I've modified the source to resemble the standard JSON fallback mechanism as in the "procedure TJSONValueWriter.WriteTo" method.

My changed code looks like this and now appears to work without giving an Access Violation. Can you check if this was a bug and if this is a suitable fix?

procedure TJsonDataObjectsWriter.WriteTo(const AValue: TValue; const AMediaType: TMediaType;
  AOutputStream: TStream; const AActivation: IMARSActivation);
var
  LJsonBO: TJsonBaseObject;
  LEncoding: TEncoding;
begin
  if not GetDesiredEncoding(AActivation, LEncoding) then
    LEncoding := TEncoding.UTF8; // UTF8 by default

from mars.

Hi @gmurt, thanks for opening this issue.
The problem arise because since latest changes to the MessageBodyWriter mechanism, MARS do not have a fallback mechanism anymore. It will try to lookup for a MBW for one of the media types specified by the client through the Accept header and, if none matches, it raises that exception.
If you do the same request (let's say with PostMan) specifying the Accept header's value to 'application/json', everything should run smoothly. The browser (Chrome) usually send an Accept header like this: 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,/;q=0.8' and, as you can see, application/json is not listed. However the wildcard (/) is actually listed so I agree it is a bug that MARS do not properly match the wildcard against the media types each MBW states to support (through the Produces custom attribute of its definition).
I have improved (hopefully fixed) this in the develop branch and now it seems to me the general behavior of the library with respect to wildcard and quality factor specification is much better.
Please check the develop branch and if everything seems fine to you also, we can close this issue.

BTW I also noticed there was a compilation error with the Demos/JsonDataObjects project (here: b49d3b3#diff-d035c020eaab32e2aa473242ca144e82L56 ) and I fixed it also.

Thanks

from mars.

Thanks Andrea and sorry for the delay.

I will test again today and let you know how it goes.

from mars.

Any news about this issue, @gmurt ?

Thanks

from mars.

from mars.

Don't worry @gmurt and happy skiing ;-)
Best regards, Andrea

from mars.