Ignore missing properties during Jackson JSON deserialization in Java

Question

In the example

class Person {
   String name;
   int age;
}

If the JSON object has a missing property \'age\',

{
  name :          


        

Answer 1

Modern versions (2.9.6) of Jackson libraries will ignore missing creator properties by default. However, if the ObjectMapper configuration is set to:

ObjectMapper mapper = new ObjectMapper();
mapper.configure(DeserializationFeature.FAIL_ON_MISSING_CREATOR_PROPERTIES, true);

Then you'll get a deserialization error if one of the properties is missing.

Answer 2

I think you would want to use the @JsonIgnore annotation: https://fasterxml.github.io/jackson-annotations/javadoc/2.2.0/com/fasterxml/jackson/annotation/JsonIgnore.html

Answer 3

You could also change your class to use an Integer instead of an int, in which case Jackson will handle null/missing "age" values properly. Just adding this answer for those looking for an alternative that doesn't involve using annotations.

class Person {
   String name;
   Integer age;
}

Answer 4

@JsonIgnoreProperties(ignoreUnknown = true) on the class level worked for me.

Answer 5

I think what you want is

@JsonSerialize(include = JsonSerialize.Inclusion.NON_NULL)
public class Person {
  ...
}

that's the Jackson 1.x way. I think there's a new way in 2.x. Something like

@JsonInclude(Include.NON_NULL)
public class Person {
  ...
}

These will tell Jackson to only serialize values that are not null, and don't complain when deserializing a missing value. I think it will just set it to the Java default.

Answer 6

Annotation based approach is a better way for ignoring but If needed. The manual way of deserialization:

ObjectMapper mapper = new ObjectMapper().configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
Person       person = mapper.readValue(jsonFileReader, Person.class);