Custom marshaling/unmarshaling of object keys

Maps are marshaled/unmarshaled as JSON objects. But if you have a map that has keys other than a string type, how can you marshal/unmarshal it to JSON?

How to do it...

The solution depends on the exact type of the key:

1. Maps with key types derived from string or integer types can be marshaled/unmarshaled using the standard library methods:

   type Key int64
   func main() {
        var m map[Key]int
        err := json.Unmarshal([]byte(`{"123":123}`), &m)
       if err!=nil {
          panic(err)
       }
        fmt.Println(m[123]) // Prints 123
   }

2. If map keys require additional processing for marshaling/unmarshaling, implement the encoding.TextMarshaler and encoding.TextUnmarshaler interfaces:

   // Key is an uint that is encoded as an hex strings for JSON key
   type Key uint
   func (k *Key...