How to debug JSON binding errors in REST - json

Question

I have a Spring MVC application with a few REST interfaces exposed and is running on an Apache Tomcat instance.
I'm wondering if there are any ways to troubleshoot the data binding errors when trying to POST to an end point. So when I post some JSON I would like to find out why the data binding is failing (when Spring converts this to an object at the Controller). I might have to do some config changes to the apache server to increase the debugging level to show more info or increase the logging level in my application (log4j) to display any errors that Spring throws out. Wondering if anyone can help me find ways to debug databinding issues.
Here is the request/response log from the Chrome's dev console for the failed request. If I simplify the JSON structure, it does seem to bind but I'd like to find out which specific JSON attributes are causing the problem.
Request URL:http://localhost:8080/entryrive-service/user/6/entry/
Request Method:POST
Status Code:400 Bad Request
Request Headersview source
Accept:application/json, text/plain, */*
Accept-Encoding:gzip,deflate,sdch
Accept-Language:en-US,en;q=0.8
Connection:keep-alive
Content-Length:667
Content-Type:application/json;charset=UTF-8
Host:localhost:8080
Origin:http://localhost:8383
Referer:http://localhost:8383/entryrive-client/app/index.html
User-Agent:Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36
Request Payloadview source
{id:null, title:Sprouts Farmers Market, entryDate:1388559600000, entryPayerId:[6], notes:test,…}
entryCreaterId: null
entryDate: 1388559600000
entryItemEntry: []
entryPayerId: [6]
entrySimpleEntry: {id:null, itemDescription:null, simpleUserIdAndLiableCost:[,…]}
entryTotal: "30"
groupId: 3
id: null
notes: "test"
title: "Sprouts Farmers Market"
userId: null
Response Headersview source
Access-Control-Allow-Credentials:true
Access-Control-Allow-Origin:http://localhost:8383
Connection:close
Content-Language:en
Content-Length:968
Content-Type:text/html;charset=utf-8
Date:Sun, 05 Jan 2014 19:50:05 GMT
Server:Apache-Coyote/1.1

Answer 1

Increasing the logging level of Spring framework did seem to show up what Spring has been upto
log4j.logger.org.springframework=ALL