How Can Jackson Ignore Unknown Fields in JSON Objects?

Ignoring Newly Added Fields in JSON Objects with Jackson

When working with JSON data, it is common for objects to evolve over time, leading to the addition of new fields. However, if your application relies on parsing JSON objects into POJO (Plain Old Java Object) classes, the presence of new fields can cause errors.

To address this challenge, Jackson provides an annotation called @JsonIgnoreProperties, which allows you to instruct Jackson to ignore fields that do not match the corresponding POJO class.

Global Ignore of New Fields

To ignore newly added fields on all JSON objects that are parsed, add the following annotation to the top of your POJO class:

@JsonIgnoreProperties(ignoreUnknown = true)

By setting ignoreUnknown to true, Jackson will automatically ignore fields that are present in the JSON object but not defined in the POJO class.

Specific Ignore of New Fields

If you want to ignore specific fields instead of all unknown fields, you can use the @JsonIgnore annotation:

@JsonIgnore
private String newField;

This annotation will prevent Jackson from serializing or deserializing the specified field.

Note:

The import for the @JsonIgnoreProperties annotation depends on the version of Jackson you are using:

• For Jackson 2.x, use: import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
• For Jackson 1.x, use: import org.codehaus.jackson.annotate.JsonIgnoreProperties;

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