Converting associative array request parameters to JSON with Jackson - json

Question

I am the recipient of a webhook POST that looks like this, which I have decoded for readability.
id=12345&event=this_event&payload[customer][name]=ABC Company&payload[customer][city]=New York&payload[service][name]=New Customer&payload[service][action]=New
Using Spring MVC, I can easily get this into a Map<String, Sting> that looks like this
{id=97659204, event=test, payload[customer][name]=ABC Company, payload[customer][city]=New York, payload[service][name]=New Customer, payload[service][action]=New}
I need to parse every parameter (or Map key) that starts with "payload" into a JSON object.
My desired output from parsing the request parameters that start with "payload" would look something like this
{
customer : {
name : "ABC Company",
city : "New York"
},
service : {
name : "New Customer",
action : "New"
}
}
With the final state being a call to Jackson's ObjectMapper to turn that JSON into a POJO.
Since I have no control over the data format begin sent to me, what is the best/correct option for parsing those request parameters into a JSON object?
Thanks.

Answer 1

I ended up writing a custom parser for the payload[][][] parameters being passed in. It uses regex matcher and then recursion to analyze each parameter, traverse a Map of 1...n Maps and then the resulting Map makes perfect JSON.
#RequestMapping(value = "/receiver", method = RequestMethod.POST)
#ResponseBody
public void receiver(#RequestParam Map<String, Object> requestBody) throws IOException {
Pattern pattern = Pattern.compile("\\[([^\\]]+)]");
Map<String, Object> payloadMap = new HashMap<>();
Matcher matcher = null;
List<String> levels = null;
for (String key : requestBody.keySet()) {
if (key.startsWith("payload")) {
matcher = pattern.matcher(key);
levels = new ArrayList<>();
while (matcher.find()) {
levels.add(matcher.group(1));
}
payloadMap = nestMap(payloadMap, levels.iterator(), (String) requestBody.get(key));
}
}
LOG.debug(mapper.writeValueAsString(payloadMap));
}
#SuppressWarnings("unchecked")
private Map<String, Object> nestMap(Map<String, Object> baseMap, Iterator<String> levels, String value) {
String key = levels.next();
if (!levels.hasNext()) {
baseMap.put(key, value);
} else {
if (!baseMap.containsKey(key)) {
baseMap.put(key, nestMap(new HashMap<String, Object>(), levels, value));
} else {
baseMap.put(key, nestMap((Map<String, Object>) baseMap.get(key), levels, value));
}
}
return baseMap;
}