How to Handle Unrecognized Fields in Jackson JSON Deserialization?

Jackson and JSON: Error Handling with Unrecognized Fields

The issue arises when Jackson encounters an unrecognized property "wrapper" that it attempts to map to the Wrapper class. Since the field is not defined in the target class, it fails with an "UnrecognizedPropertyException."

Solution

To resolve this issue, leverage Jackson's JsonIgnoreProperties annotation. This annotation can be applied at the class level to specify that any unrecognized properties should be ignored. By default, it ignores any properties not explicitly defined in the POJO.

An example usage of this annotation:

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties
class Wrapper { ... }

This annotation ensures that any properties in the JSON that do not correspond to defined fields in the Wrapper class will be skipped during deserialization.

Advanced Option

For cases where you want to ignore all undeclared properties, even those with a getter and setter method defined in the target class, you can use the ignoreUnknown flag:

@JsonIgnoreProperties(ignoreUnknown = true)
class Wrapper { ... }

By specifying ignoreUnknown = true, Jackson will disregard any properties in the JSON that do not have a corresponding field in the Wrapper class, regardless of the existence of getter or setter methods.

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