How to using ObjectMapper to map value of an json property to Object when my object have an contractor set this property is null

I am usng google DirectionsResul Object

And then I want to using Object mapper to mapping this json to DirectionsResul Object

{
  "geocoded_waypoints": [],
  "routes": [
    {
      "bounds": {},
      "legs": [
        {
          "distance": {
            "human_readable": "13 km",
            "in_meters": 13175
          },
          "duration": {
            "human_readable": "37 phút",
            "in_seconds": 2206
          },
          "steps": []
        }
      ],
      "overview_polyline": {
        "points": "aaaa"
      },
      "warnings": [],
      "waypoint_order": []
    }
  ]
}

Using this code

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);

DirectionsResult result;
result = objectMapper.readValue(json, DirectionsResult.class.);

All is ok but overview_polyline can’t mapping, the points value is null and I see in the EncodedPolyline have a contractor like this

public EncodedPolyline() {
        this.points = null;
    }

So how can I mapping the points value to the DirectionsResul Object

Here is my result I got

Here is all the code that can run

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.maps.model.DirectionsResult;
public void testGetDirections() throws NetworkException {
String json = "{n" +
                "  "geocoded_waypoints": [],n" +
                "  "routes": [n" +
                "    {n" +
                "      "bounds": {n" +
                "        "northeast": {n" +
                "          "lat": 34.1358593,n" +
                "          "lng": -117.922066n" +
                "        },n" +
                "        "southwest": {n" +
                "          "lat": 33.815582,n" +
                "          "lng": -118.3516983n" +
                "        }n" +
                "      },n" +
                "      "legs": [n" +
                "        {n" +
                "          "distance": {n" +
                "            "human_readable": "13 km",n" +
                "            "in_meters": 13175n" +
                "          },n" +
                "          "duration": {n" +
                "            "human_readable": "37 phút",n" +
                "            "in_seconds": 2206n" +
                "          },n" +
                "          "steps": [n" +
                "            {n" +
                "              "distance": {n" +
                "                "human_readable": "10 ft",n" +
                "                "in_meters": 3n" +
                "              },n" +
                "              "duration": {n" +
                "                "human_readable": "1 min",n" +
                "                "in_seconds": 0n" +
                "              }n" +
                "            }n" +
                "          ]n" +
                "        }n" +
                "      ],n" +
                "      "overview_polyline": {n" +
                "        "points": "{ashdasda}"n" +
                "      },n" +
                "      "warnings": [],n" +
                "      "waypoint_order": []n" +
                "    }n" +
                "  ]n" +
                "}";

        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
        objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);

        DirectionsResult goongMapsDirectionResult;


        try {
            goongMapsDirectionResult = objectMapper.readValue(json, DirectionsResult.class.);
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }
    }

Answer

The problem is that there is no setter for points on EncodedPolyline.

One way to work around this is to use a DeserializationProblemHandler:

public class SO69242058 {

    public static void main(String args[]) throws JsonProcessingException {
        String json = "{n" +
                      "  "geocoded_waypoints": [],n" +
                      "  "routes": [n" +
                      "    {n" +
                      "      "bounds": {n" +
                      "        "northeast": {n" +
                      "          "lat": 34.1358593,n" +
                      "          "lng": -117.922066n" +
                      "        },n" +
                      "        "southwest": {n" +
                      "          "lat": 33.815582,n" +
                      "          "lng": -118.3516983n" +
                      "        }n" +
                      "      },n" +
                      "      "legs": [n" +
                      "        {n" +
                      "          "distance": {n" +
                      "            "human_readable": "13 km",n" +
                      "            "in_meters": 13175n" +
                      "          },n" +
                      "          "duration": {n" +
                      "            "human_readable": "37 phút",n" +
                      "            "in_seconds": 2206n" +
                      "          },n" +
                      "          "steps": [n" +
                      "            {n" +
                      "              "distance": {n" +
                      "                "human_readable": "10 ft",n" +
                      "                "in_meters": 3n" +
                      "              },n" +
                      "              "duration": {n" +
                      "                "human_readable": "1 min",n" +
                      "                "in_seconds": 0n" +
                      "              }n" +
                      "            }n" +
                      "          ]n" +
                      "        }n" +
                      "      ],n" +
                      "      "overview_polyline": {n" +
                      "        "points": "{ashdasda}"n" +
                      "      },n" +
                      "      "warnings": [],n" +
                      "      "waypoint_order": []n" +
                      "    }n" +
                      "  ]n" +
                      "}";

        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
        //objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
        objectMapper.addHandler(new DeserializationProblemHandler() {

            @Override
            public boolean handleUnknownProperty(DeserializationContext ctxt, JsonParser p,
                                                 JsonDeserializer<?> deserializer, Object beanOrClass,
                                                 String propertyName) throws IOException {
                EncodedPolyline encodedPolyline = (EncodedPolyline)beanOrClass;
                try {
                    Field f = EncodedPolyline.class.getDeclaredField("points");
                    f.setAccessible(true);
                    f.set(encodedPolyline, p.readValueAs(String.class));
                } catch (NoSuchFieldException | IllegalAccessException e) {
                   throw new RuntimeException(e);
                }
                return true;
            }
        });

        DirectionsResult goongMapsDirectionResult;

        goongMapsDirectionResult = objectMapper.readValue(json, DirectionsResult.class);
    }
}

I’ve removed objectMapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES) so that the error occurs when Jackson tries to set points. Then we set it reflectively.