Introduce request parameter based content negotiation for ResponseBody / HttpMessageConverter approach [SPR-7517]

[spring-projects-issues]

Neil Laurance opened SPR-7517 and commented

My client application may not support setting the HTTP Accept header.

When using views, I can configure a ContentNegotiatingViewResolver to ignore the accept header, and use a request parameter instead.

But if I want to use a ResponseBody / HttpMessageConverter approach, this only supports the HTTP Accept header.

From AnnotationMethodHandlerAdapter$ServletHandlerMethodInvoker#writeWithMessageConverters:

List<MediaType> acceptedMediaTypes = inputMessage.getHeaders().getAccept();

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Affects: 3.0 M1, 3.0 M2, 3.0 M3, 3.0 M4, 3.0 RC1, 3.0 RC2, 3.0 RC3, 3.0 GA, 3.0.1, 3.0.2, 3.0.3, 3.0.4

Issue Links:

• Content negotiation improvements [SPR-8410] #13057 Content negotiation improvements ("is superseded by")

1 votes, 2 watchers

[spring-projects-issues]

Neil Laurance commented

There is a workaround.

1. Subclass the AnnotationMethodHandlerAdapter
2. Override the createHttpInputMessage method, something similar to:

public class MyAnnotationMethodHandlerAdapter extends AnnotationMethodHandlerAdapter {

private String requestParam = "accept";
private Map<String, MediaType> mediaTypesMap;

@Override protected HttpInputMessage createHttpInputMessage(HttpServletRequest request) throws Exception {
HttpInputMessage message = super.createHttpInputMessage(request);
String accept = request.getParameter(requestParam);
if (accept == null || accept.isEmpty()) {
return message;
} else {
return new MyHttpInputMessage(message, mediaTypesMap.get(accept));
}
}

public void setMediaTypesMap(Map<String, MediaType> mediaTypesMap) {
this.mediaTypesMap = mediaTypesMap;
}

public void setRequestParam(String requestParam) {
this.requestParam = requestParam;
}
}

3. Provide MyHttpInputMessage decorator that replaces Accept headers with requested mediattype.

[spring-projects-issues]

Rossen Stoyanchev commented

This is now resolved. To configure, declare a ContentNegotiationManager bean with a ParameterContentNeogiationStrategy and use it in turn to configure RequestMappingHandlerMapping, RequestMappingHandlerAdapter and ExceptionHandlerExceptionResolver.