How to produce JSON with sorted keys in Go?

Question

In python you can produce JSON with keys in sorted order by doing

import json
print json.dumps({\'4\': 5, \'6\': 7}, sort_keys=True, indent=4, separators=(\'         


        

Answer 1

The json package always orders keys when marshalling. Specifically:

• Maps have their keys sorted lexicographically

• Structs keys are marshalled in the order defined in the struct

The implementation lives here ATM:

• http://golang.org/src/pkg/encoding/json/encode.go?#L359

Answer 2

Gustavo Niemeyer gave great answer, just a small handy snippet I use to validate and reorder/normalize []byte representation of json when required

func JsonRemarshal(bytes []byte) ([]byte, error) {
    var ifce interface{}
    err := json.Unmarshal(bytes, &ifce)
    if err != nil {
        return []byte{}, err
    }
    output, err := json.Marshal(ifce)
    if err != nil {
        return []byte{}, err
    }
    return output, nil
}