Spring Boot @JsonFormat Issues & Solutions

In Spring Boot, you can control the formatting of JSON serialization and deserialization using the @JsonFormat annotation, which allows you to specify the formatting of types such as dates, times, and numbers. If @JsonFormat is not taking effect, there could be several reasons and solutions for it.

1. Check the location of the annotation: Ensure that the @JsonFormat annotation is placed on the fields or methods that need to be serialized/deserialized.
2. Check dependencies: Ensure that the relevant dependencies, such as jackson-datatype-jsr310 for handling Java 8 date and time types, have been correctly imported.
3. Check the configuration of ObjectMapper: If you have customized the ObjectMapper, you may need to enable the corresponding feature in the configuration. For example, if you are using an application.yaml configuration file, you can add the following configuration.
4. Spring Jackson with a date format of yyyy-MM-dd HH:mm:ss.
5. Alternatively, if you are using Java Config, you can add the following code to your configuration class.
6. Create a method named “objectMapperBuilder” that returns a Jackson2ObjectMapperBuilder object with a specified date format.
7. Check the access permissions of the object: ensure that the fields to be serialized/deserialized have public getter and setter methods.

If none of the above methods have resolved the issue, you can try using debugging tools to view specific error messages or provide more code and configuration information for better understanding of the issue.