Populate ComboBox from JSON Object

Question

Hello, I have below Json
[
{
"customerid": 1,
"name": "ABS",
"email": "true",
"reference": "2016-03-21T10:44:32+03:00",
"status": 0,
"dateupdated": "2017-12-07T04:56:05.583"
},
{
"customerid": 2,
"name": "BMS",
"email": "true",
"reference": "2016-03-13T19:17:54+03:00",
"status": 0,
"dateupdated": "2017-12-07T04:56:05.757"
},
{
"customerid": 3,
"name": "XYA",
"email": "true",
"reference": "2016-03-13T19:17:54+03:00",
"status": 0,
"dateupdated": "2017-12-07T04:56:05.757"
}
]
In my windows form I create class API.cs
class  API
{
}
public   class  RootObject
{
public   int  customerid {  get ;  set ; }
public   string  name {  get ;  set ; }
public   string  email {  get ;  set ; }
public  DateTime reference {  get ;  set ; }
public   int  status {  get ;  set ; }
public  DateTime dateupdated {  get ;  set ; }
}
I need to populate combo box customer_cb with "name".  I use DataContractJsonSerializer
WebClient client =  new  WebClient();
string  json = client.DownloadString(url);
using  (var ms =  new  MemoryStream(Encoding.Unicode.GetBytes(json)))
{
DataContractJsonSerializer deserializer =  new  DataContractJsonSerializer( typeof (RootObject));
RootObject obj = (RootObject)deserializer.ReadObject(ms);
// Assign data to combo box
foreach (var name  in  obj.name)
{
ComboboxItem item =  new  ComboboxItem();
item.Text = name.ToString();
customer_cb.Items.Add(item);
}
}
When I run the application I get error
Object Reference not  set  to an instance of an  object
Please help.

Salman Mushtaq · Answer

Dear Laximidhar,   It's windows form application.

Laxmidhar Sahoo · Answer

sir may tell the application type means win or asp.net or wpf