How to not marshal an empty struct into JSON with Go?

Question

I have a struct like this:

type Result struct {
    Data       MyStruct  `json:\"data,omitempty\"`
    Status     string    `json:\"status,omitempty\"`
    R         


        

Answer 1

Data is an initialized struct, so it isn't considered empty because encoding/json only looks at the immediate value, not the fields inside the struct.

Unfortunately returning nil from json.Marhsler currently doesn't work:

func (_ MyStruct) MarshalJSON() ([]byte, error) {
    if empty {
        return nil, nil // unexpected end of JSON input
    }
    // ...
}

You could give Result a marshaler as well, but it's not worth the effort.

The only option, as Matt suggests, is to make Data a pointer and set the value to nil.