Java Spring Deserializing Nested objects using RestTemplate

Question

I am using Java Spring boot restTemplate and I am trying to deserialize the below JSON into their corresponding objects. However it is returning null.

Am I doing this the right way? Should I return a String response Entity and then convert?

{
  "Events": [
    {
      "Id": 3584588,
      "Url": "https://api.wildapricot.org/v2/accounts/257051/Events/3584588",
      "EventType": "Regular",
      "StartDate": "2019-10-07T07:00:00-05:00",
      "EndDate": "2019-10-11T12:00:00-05:00",
      "Location": "Renaissance Montgomery Hotel & Spa",
      "RegistrationEnabled": false,
      "RegistrationsLimit": null,
      "PendingRegistrationsCount": 0,
      "ConfirmedRegistrationsCount": 0,
      "CheckedInAttendeesNumber": 0,
      "InviteeStat": {
        "NotResponded": 0,
        "NotAttended": 0,
        "Attended": 0,
        "MaybeAttended": 0
      },
      "Tags": [
        "event"
      ],
      "AccessLevel": "AdminOnly",
      "StartTimeSpecified": true,
      "EndTimeSpecified": true,
      "HasEnabledRegistrationTypes": false,
      "Name": "2020 Montgomery IT Summit"
    },
    {
      "Id": 3584591,
      "Url": "https://api.wildapricot.org/v2/accounts/257051/Events/3584591",
      "EventType": "Rsvp",
      "StartDate": "2019-10-03T00:00:00-05:00",
      "EndDate": "2019-10-31T00:00:00-05:00",
      "Location": "Here",
      "RegistrationEnabled": true,
      "RegistrationsLimit": null,
      "PendingRegistrationsCount": 0,
      "ConfirmedRegistrationsCount": 0,
      "CheckedInAttendeesNumber": 0,
      "InviteeStat": {
        "NotResponded": 0,
        "NotAttended": 0,
        "Attended": 0,
        "MaybeAttended": 0
      },
      "Tags": [
        "volunteer"
      ],
      "AccessLevel": "Public",
      "StartTimeSpecified": false,
      "EndTimeSpecified": false,
      "HasEnabledRegistrationTypes": true,
      "Name": "Volunteer Event"
    }
 ]
}

Here is my call:

ResponseEntity<WaEvents> response = restTemplate.exchange(uri,
                HttpMethod.GET,
                request,
                WaEvents.class
        );

return response.getBody().getEvents();

Here is my WaEvents Class:

@Data
public class WaEvents implements Serializable {

    @JsonUnwrapped
    @JsonProperty("Events")
    private List<WaEvent> events;
}

Here is the WaEvent Class

@Data
@JsonIgnoreProperties(ignoreUnknown = true)
public class WaEvent {

    @JsonProperty("Id")
    public Integer id;

    @JsonProperty("Name")
    public String name;

    @JsonProperty("Location")
    public String location;

    @JsonProperty("StartDate")
    public LocalDate startDate;

    @JsonProperty("EndDate")
    public LocalDate endDate;

    @JsonProperty("IsEnabled")
    public Boolean isEnabled;

    @JsonProperty("Description")
    public String description;

    @JsonProperty("RegistrationLimit")
    public Integer RegistrationLimit;

}

Yes. I replaced WaEvent with String and I can see the response body has the data. code ResponseEntity<String> response = restTemplate.exchange(uri, HttpMethod.GET, request, String.class ); — enderjs
– enderjs, Commented May 23, 2020 at 21:42
Then can you please post the full code of the WaEvent and WaEvents — Ehab Qadah
– Ehab Qadah, Commented May 23, 2020 at 22:04
That is the complete code. I am using lomback for the getters, setters and constructor if that is what you are looking for. Maybe I should try and do it manually? — enderjs
– enderjs, Commented May 23, 2020 at 22:23

Sébastien Temprado · Accepted Answer · 2020-05-23 22:02:58Z

3

As explained here with an example :

public class Parent {
    public int age;
    public Name name;
}
public class Name {
    public String first, last;
}

Without @JsonUnwrapped, the JSON is :

{
    "age" : 18,
    "name" : {
        "first" : "Joey",
        "last" : "Sixpack"
    }
}

With @JsonUnwrapped, the JSON is :

{
    "age" : 18,
    "first" : "Joey",
    "last" : "Sixpack"
}

So @JsonUnwrapped will flatten the properties and events won't exist anymore :

{
    "Id": 3584588,
    "Name": "2020 Montgomery IT Summit",
    "Location": "Renaissance Montgomery Hotel & Spa",
    "StartDate": "2019-10-07T07:00:00-05:00",
    "EndDate": "2019-10-11T12:00:00-05:00",
    ...
}

Try to remove @JsonUnwrapped

answered May 23, 2020 at 22:02

Sébastien Temprado

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1 Comment

enderjs Over a year ago

I figured it out.... I was using the wrong Jackson package.... I was using org.codehaus.jackson versus com.fasterxml.jackson.core ...I think I would have still had the problem and your answer taught me something as well! Thanks.

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