Jackson @JsonIgnoreProperties multiple fields with Kotlin

Question

I'm having trouble using @JsonIgnoreProperties with kotlin. I need to ignore more than one property, and I see many tutorial/SO questions where, with java, usually you do something like that:

@JsonIgnoreProperties({ "p0", "p1", "p2" })
class Example(){...}

So in kotlin it would be:

@JsonIgnoreProperties(value = arrayOf( "p0", "p1", "p2" ))
class Example(){...}

The value field of the JsonIgnoreProperties interface should accept array, since it's declared in this way:

public String[] value() default { };

But the compiler complains and want a string, not an array. I can't even duplicate the annotation, so how should I do to ignore more than one field?

EDIT: Seems like it's a kotlin missing feature, implemented since 1.2 beta. it will be possible to use value = ["p0", "p1", "p2"] for annotations. Before 1.2 beta it's possible to use @JsonIgnoreProperties("p0", "p1", "p2"), no way to prepend the array with value =

Answer 1

You can use the spread operator here, which is what the Java to Kotlin converter does with your example code, and also what Android Studio suggests as a quick fix:

@JsonIgnoreProperties(value = *arrayOf( "p0", "p1", "p2" ))
class Example { ... }

This works because array types in annotation parameters get converted to varargs in Kotlin, so you could just do this if you're not using an Array from somewhere else:

@JsonIgnoreProperties("p0", "p1", "p2")
class Example