Resolving Nested JSON issue using Spring-Hibernate - json

Question

I am using spring mvc and jackson for my extjs application and stuck at some thing similar.
I have my list of records returned from DB using Hibernate.
DAO class:
#SuppressWarnings("unchecked")
#Override
public List<CandidateStatus> getcandidateStatus() {
//return hibernateTemplate.find("select candstat.candidate.firstName as firstName,candstat.candidate.lastName as lastName,candstat.candidate.email as email,candstat.statusTitle as statusTitle,candstat.requirement.client.clientName as clientName,candstat.requirement.reqTitle as reqTitle from CandidateStatus as candstat");
return hibernateTemplate.find("from CandidateStatus");
//return hibernateTemplate.find("from CandidateStatus candstat left outer join candstat.candidate left outer join candstat.requirement left outer join candstat.requirement.client");
//return hibernateTemplate.find("from Candidates as cands inner join cands.candidateStats");
}
**Service class**
public List<CandidateStatus> getCandidateStatusList()
{
//return candidatesDAO.getCandidates();
return candidatesDAO.getcandidateStatus();
}
Controller class
#RequestMapping(value="/candidates/view.action")
public #ResponseBody Map<String,? extends Object> view() throws Exception {
try{
//List<Candidates> candidates = candidatesService.getCandidatesList();
List<CandidateStatus> candidatestatus = candidatesService.getCandidateStatusList();
return getMap(candidatestatus);
} catch (Exception e) {
return getModelMapError("Error retrieving Candidates from database.");
}
private Map<String,Object> getMap(List<CandidateStatus> candidatestatus){
Map<String,Object> modelMap = new HashMap<String,Object>(3);
modelMap.put("success", true);
modelMap.put("total", candidatestatus.size());
modelMap.put("data", candidatestatus);
return modelMap;
}
private Map<String,Object> getModelMapError(String msg){
Map<String,Object> modelMap = new HashMap<String,Object>(2);
modelMap.put("message", msg);
modelMap.put("success", false);
return modelMap;
}
Before adding it to the map I want to format the JSON in a required format as per my application.I get the format in a nested manner which is not accepted by extjs.
{
"data": [
{
"id": 29,
"requirement": {
"id": 27,
"client": {
"id": 12,
"clientName": "HireCraft"
},
"clientId": 12,
"reqTitle": "Support Engineer"
},
"reqid": 27,
"resid": 45,
"candidate": {
"id": 45,
"firstName": "Vikram",
"lastName": "",
"email": "bj.vikram#gmail.com"
},
"statusTitle": "Shortlisted"
}],
"success":true,
"total":7668
}
I want the json to be flat file like this without nesting.
"data": [ {
"clientName": "ABC"
"firstName": "Suynil",
"lastName": "Seelam",
"email": "ss.seelam#gmail.com",
"reqTitle": "Java"}]success:true,total:768}
Can you please guide me how I can achive this.I have stuglling for long over this issue!
I tried a bit and getting something likethis.
private Map<String,Object> getMap(List<CandidateStatus> candidatestatus){
Map<String,Object> modelMap = new HashMap<String,Object>(3);
Map<String,Object> candDetails = new HashMap<String,Object>(7);
Iterator<CandidateStatus> iterator=candidatestatus.iterator();
CandidateStatus astring = new CandidateStatus();
String Client;
String Fname;
String Lname;
String Email;
String Phone;
String Status;
String Require;
while(iterator.hasNext())
{
astring = iterator.next();
/*System.out.println(astring.getCandidate().getFirstName());
System.out.println(astring.getCandidate().getLastName());
System.out.println(astring.getCandidate().getEmail());
System.out.println(astring.getStatusTitle());
System.out.println(astring.getRequirement().getReqTitle());*/
Client = astring.getRequirement().getClient().getClientName();
Fname = astring.getCandidate().getFirstName();
Lname = astring.getCandidate().getLastName();
Email = astring.getCandidate().getEmail();
Phone = astring.getCandidate().getPhone();
Status = astring.getStatusTitle();
Require= astring.getRequirement().getReqTitle();
candDetails.put("clientName",Client);
candDetails.put("firstName",Fname);
candDetails.put("lastName",Lname);
candDetails.put("email",Email);
candDetails.put("phone",Phone);
candDetails.put("statusTitle",Status);
candDetails.put("reqTitle",Require);
//jsonMap.put("root", candDetails);
//System.out.println(jsonMap);
}
//System.out.println("----"+candDetails+"----");
modelMap.put("success", true);
modelMap.put("total",candDetails.size());
modelMap.put("data",candDetails );
return modelMap;
Now when I try to add candDetails to the modelMap I get only the LAST record.Why???
Thanks

Answer 1

I don't think your second example is valid JSON, at least according to json.org. An object is defined as:
an unordered set of name/value pairs. An object begins with { (left brace) and ends with } (right brace). Each name is followed by : (colon) and the name/value pairs are separated by , (comma).
That tells me that JSON has to start with a '{' and end with a '}'.

Answer 2

Your approach will work, if you change you work with map candDetails witch is kinda silly. In your loop you put data with same key, thats why you get data with last iterate.
I suggest you to write custom wrapper object(lets call it CandidateStatusWrapper and build there all structure you need. Then you just return list of wrapped objects.
Wrapper example:
class CandidateStatusWrapper {
String clientName;
String firstName;
public CandidateStatusWrapper(String clientName, String firstName) {
this.clientName = clientName;
this.firstName = firstName;
}
}
Change your map:
Map<String,Object> candDetails = new HashMap<String,Object>(7);
into list:
List<CandidateStatusWrapper> = new ArrayList<CandidateStatusWrapper >();
Loop in Controller:
while(iterator.hasNext())
{
astring = iterator.next();
Client = astring.getRequirement().getClient().getClientName();
Fname = astring.getCandidate().getFirstName();
CandidateStatusWrapper wrapped = new CandidateStatusWrapper(Client, Fname);
candDetails.add(wrapped);
}