restful webservice get list of objects - spring

Question

My rest webservice returns the following output:
{
"result": {
"TICKET1": {
"number": "TICKET1",
"description": "aa"
},
"TICKET2": {
"number": "TICKET2",
"description": "dd"
}
}
}
To convert this into a list of Tickets I tried as below.
class TicketResponse {
private List<Ticket> result;
// Get Set
}
class Ticket {
private String number;
private String description;
// Get Set
}
TicketResponse response = restTemplate.getForObject(WEB_SERVICE_URL, TicketResponse.class);
But I get response as null. How to do this.

Answer 1

I'll provide two ways to do with the JSON structure you have.
Option 1:
Modify your TicketResponse class like below:
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.stream.Collectors;
import com.fasterxml.jackson.annotation.JsonAnySetter;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
public class TicketResponse {
#JsonProperty("result")
private Map<String, Ticket> ticketsMap = new HashMap<>();
#JsonAnySetter
public void setUnknownField(String name, Ticket value) {
ticketsMap.put(name, value);
}
#JsonIgnore private List<Ticket> ticketsList;
public List<Ticket> getTicketsList() {
return ticketsMap.entrySet().stream().map(Entry::getValue).collect(Collectors.toList());
}
}
then you can get your list of tickets from:
response.getTicketsList();
Option 2:
Read your response in to a String
String response = restTemplate.getForObject(WEB_SERVICE_URL, String.class);
and use below code to convert it to a List<Ticket>
ObjectMapper mapper = new ObjectMapper();
JsonNode jsonNode = mapper.readTree(response);
JsonNode wantedJsonNode = jsonNode.get("result");
Map<String, Ticket> map =
mapper.convertValue(wantedJsonNode, new TypeReference<Map<String, Ticket>>() {});
List<Ticket> tickets =
map.entrySet().stream().map(Entry::getValue).collect(Collectors.toList());

Answer 2

The object you provided doesn't contain a list/array, which would be inside square brackets, like this:
{
"result": {
"tickets": [
{
"number": "TICKET1",
"description": "aa"
},
{
"number": "TICKET2",
"description": "dd"
}
]
}
}
Change your service if possible to return a list/array. Otherwise what you have is an object with individual fields named TICKET1 and TICKET2, so you'll need a field for each.

Answer 3

TicketResponse must have a structure that corresponds to response of the service.
You can change your TicketResponse class and add getTicketArray method:
public class TicketResponse {
private Map<String,Ticket> result;
// getter setter
public List<Ticket> getTicketsAsArray(){
return new ArrayList<Ticket>(result.values());
}
}