Issue in populating combobox using Json from postgresql in ExtJs and Servlets - json

Question

In my Java EE web application there is a combobox in a form panel. I tried to populate this combobox from my postgresql database using JsonReader. I am using ExtJs 3.0 and JSP & Sevlets.
This is my ExtJs code segment for combobox and JsonReader.
var vehicleStore = new Ext.data.Store({
proxy : new Ext.data.HttpProxy({
url : "http://" + host + ":" + port + "/" + projectName + "/"
+ "DeliveryVehicle"
}),
reader : new Ext.data.JsonReader({
idProperty : 'vCode',
root : 'vehicles',
fields : [ {
name : 'vCode'
}, {
name : 'vRegNum'
} ]
}),
autoLoad : true
});
{
xtype : 'combo',
name : 'include_type',
fieldLabel : 'Delivery Vehicle',
emptyText : 'Delivery Vehicle',
editable : false,
hideLabel : true,
style : 'marginleft:10px',
displayField : 'vRegNum',
valueField : 'vCode',
store : vehicleStore,
flex : 1
}
And this is my DeliveryVehicle.java servlet.
package com.xontworld.ornox.Geotrack;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.xontworld.ornox.connection.ConnectionManager;
public class DeliveryVehicle extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* #see HttpServlet#HttpServlet()
*/
public DeliveryVehicle() {
//super();
// TODO Auto-generated constructor stub
}
#Override
public void init() throws ServletException {
// TODO Auto-generated method stub
super.init();
}
/**
* #see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
processRequest(request, response);
}
/**
* #see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
processRequest(request, response);
}
protected void processRequest(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
ServletContext context = getServletContext();
String dbName = context.getInitParameter("ConnectionDB");
String connectionHost = context.getInitParameter("ConnectionHost");
String connectionUser = context.getInitParameter("ConnectionUser");
String connectionPassword = context.getInitParameter("ConnectionPassword");
String port = "5433";
Statement statement = null;
ResultSet vehicleResultSet = null;
Connection pgConnection = null;
String lineString = "";
try {
pgConnection = ConnectionManager.getPostgresConnection(
connectionHost, connectionUser, connectionPassword,
dbName, port);
out.println(connectionHost+","+ connectionUser+","+ connectionPassword+","+ dbName);
statement = pgConnection.createStatement();
out.print(pgConnection);
String sql = "";
sql = "select distinct vehiclecode, registrationnumber from hoobtvehicles v WHERE v.status='1'";
vehicleResultSet = statement.executeQuery(sql);
String jsonData = "{'vehicles':[";
while (vehicleResultSet.next()) {
jsonData += "{ 'vCode' : '";
jsonData += vehicleResultSet.getString(1).trim();
jsonData += "', ";
jsonData += "'vRegNum' : '";
jsonData += vehicleResultSet.getString(2).trim();
if (vehicleResultSet.isLast()) {
jsonData += "' } ";
} else {
jsonData += "' } , ";
}
}
jsonData += "]}";
out.print(jsonData);
} catch (Exception e) {
// TODO Auto-generated catch block
out.println(e.toString());
e.printStackTrace();
}
}
}
And this is my Json data.
{'vehicles':[{ 'vCode' : '1001', 'vRegNum' : 'XY-100-123' } , { 'vCode' : '1002', 'vRegNum' : 'GY-122-120' } , { 'vCode' : '1000000001', 'vRegNum' : 'XY-100-123' } ]}
The problem is it doesn't load the combobox and it doesn't even print anything in my eclipse console. And also it doesn't show any error message in firebug console. I use alert to check the size of the vehicleStore. It'a zero. Anyone has an idea what's going on here.
I would be much obliged if anyone please be so kind enough to explain what's wrong with my codes and how should I correct it?
Thanks a lot