What's the canonical way to get the following enum to write the intValue when mapping this to a String with a normal ObjectMapper? As-is, it writes the text (for example DEBUG) but I want it to write a 1 (JSON number).

enum class SEVERITY(val intValue: Int) {
    DEBUG(1),
    VERBOSE(2),
    INFO(3),
    WARN(4),
    ERROR(5),
    CRITICAL(6)
}

What's the canonical way to get the following enum to write the intValue when mapping this to a String with a normal ObjectMapper? As-is, it writes the text (for example DEBUG) but I want it to write a 1 (JSON number).

enum class SEVERITY(val intValue: Int) {
    DEBUG(1),
    VERBOSE(2),
    INFO(3),
    WARN(4),
    ERROR(5),
    CRITICAL(6)
}

• kotlin
• jackson

1 Answer 1

Based on this answer, you can annotate a method with @JsonValue that returns an Int, and Jackson will use the return value of that method to write the JSON.

In this case, that method will be the getter for intValue, which you can annotate like this:

enum class Severity(@get:JsonValue val intValue: Int) { ... }

You can also omit "get:", in which case the annotation will be applied to the backing field of intValue, which also works.