Spring Data REST: projection representation of single resource

Question

I have a simple UserRepository which exposed using Spring Data REST. Here is the User entity class:

@Document(collecti         


        

Answer 1

I was looking at something similar recently and ended up going round in circles when trying to approach it from the Spring Data /Jackson side of things.

An alternative, and very simple solution, then is to approach it from a different angle and ensure the Projection parameter in the HTTP request is always present. This can be done by using a Servlet Filter to modify the parameters of the incoming request.

This would look something like the below:

public class ProjectionResolverFilter extends GenericFilterBean {

    private static final String REQUEST_PARAM_PROJECTION_KEY = "projection";

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
            throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;

        if (shouldApply(request)) {
            chain.doFilter(new ResourceRequestWrapper(request), res);
        } else {
            chain.doFilter(req, res);
        }
    }

    /**
     * 
     * @param request
     * @return True if this filter should be applied for this request, otherwise
     *         false.
     */
    protected boolean shouldApply(HttpServletRequest request) {
        return request.getServletPath().matches("some-path");
    }

    /**
     * HttpServletRequestWrapper implementation which allows us to wrap and
     * modify the incoming request.
     *
     */
    public class ResourceRequestWrapper extends HttpServletRequestWrapper {

        public ResourceRequestWrapper(HttpServletRequest request) {
            super(request);
        }

        @Override
        public String getParameter(final String name) {
            if (name.equals(REQUEST_PARAM_PROJECTION_KEY)) {
                return "nameOfDefaultProjection";
            }

            return super.getParameter(name);
        }
    }
}