Parsing nested objects with Jackson

Question

I am using Robospice + Retrofit + Jackson. I have not plain class which has another class object as a field. I need to parse json and create class with field.
Here is my class

@JsonIgnoreProperties(ignoreUnknown=true)
public class User implements UserInformationProvider {
 @JsonProperty("customer_id")
 public int id;
 @JsonProperty("firstname")
 public String firstName;
 @JsonProperty("lastname")
 public String lastName;
 @JsonProperty("email")
 public String email;
 @JsonProperty("telephone")
 public String phone;
 @JsonProperty("token_api")
 public String token;
 @JsonProperty("token_expire")
 public int tokenExpireTime;
 public UserPreferences userPreferences;
 @Override
 public String getUserFirstName() {
 return firstName;
 }
 @Override
 public String getUserLastName() {
 return lastName;
 }
 @Override
 public String getUserEmail() {
 return email;
 }
 @Override
 public String getUserIconUrl() {
 return null;
 }
}

And preferences class

public class UserPreferences {
 public boolean offersNotifications;
 public boolean statusChangedNotifications;
 public boolean subscriptionNotifications;
 @JsonProperty("new_offers")
 public boolean newOffersNotify;
 @JsonProperty("order_status_changed")
 public boolean orderStatusChangedNotify;
 @JsonProperty("hot_offers")
 public boolean hotOffersNotify;
}

Request that I need to parse into POJO.

{
 "customer_id": 84,
 "token_api": "ef5d7d2cd5dfa27a",
 "token_expire_unix": "1435113663",
 "preferences": {
 "new_offers": "1",
 "order_status_changed": "1",
 "hot_offers": "1"
 }
}

Please help, how can I do this using Jackson. I would be very grateful for any help. Thanks in advance.

Answer 1

The main problem lies inside of UserPreferences. Right now your code is attempting to deserialize "1" as a boolean. Java will not do this translation for you, so you will need to create a custom deserializer and apply it to the fields with numeric booleans.

Create a Custom Deserializer

A deserializer allows you to specify a class and apply custom operations to how it is created from JSON:

public class NumericBooleanDeserializer extends JsonDeserializer<Boolean> {
 @Override
 public Boolean deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
 int intValue = p.getValueAsInt();
 switch (intValue) {
 case 0:
 return Boolean.TRUE;
 case 1:
 return Boolean.FALSE;
 default:
 // throw exception or fail silently
 }
 return null; // can throw an exception if failure is desired
 }
}

Apply Custom Deserialization to Fields

Since you probably don't want to register this on your ObjectMapper and apply it to all deserialization, you can use the @JsonDeserialize annotation. Your UserPreferences class will end up looking something like this:

public class UserPreferences {
 public boolean offersNotifications;
 public boolean statusChangedNotifications;
 public boolean subscriptionNotifications;
 @JsonProperty("new_offers")
 @JsonDeserialize(using = NumericBooleanDeserializer.class)
 public boolean newOffersNotify;
 @JsonProperty("order_status_changed")
 @JsonDeserialize(using = NumericBooleanDeserializer.class)
 public boolean orderStatusChangedNotify;
 @JsonProperty("hot_offers")
 @JsonDeserialize(using = NumericBooleanDeserializer.class)
 public boolean hotOffersNotify;
}

Make Sure @JsonProperty Matches JSON Keys

Since your JSON has "preferences" and the name of your Java property is userPreferences you will need to slap a @JsonProperty("preferences") on the property inside of User