func DecodeOffer(datahex string) (map[string]interface{})   {
    responce, _ := rpcClient.Call("decoderawexchange", datahex)
    var d = make(map[string]interface{})
    err := responce.GetObject(&d)
    if err != nil || d == nil {
    panic(err)
    }

    return d
}

{
  "ask": {
  "amount": 0,
  "assets": [
    {
      "assetref": "74-266-27408",
      "name": "USD",
      "qty": 5000
    }
  ]
  },
  "cancomplete": true,
  "candisable": true,
  "complete": false,
  "offer": {
  "amount": 0,
  "assets": [
    {
      "assetref": "73-266-61482",
      "name": "BTC",
      "qty": 1
    }
  ]
  },
  "requiredfee": 0
}

type DecodedOffer struct {
    ask []Ask `json:"ask"`
    cancomplete bool `json:"cancomplete"`
    candisable bool `json:"candisable"`
    complete bool `json:"complete"`
    offer []Offer `json:"offer"`
    requiredfee int `json:"requiredfee"`
}

type Ask struct {
    ammount string `json:"ammount"`
    assets []Assets `json:"assets"`
}

type Offer struct {
    ammount string `json:"ammount"`
    assets []Assets `json:"assets"`
}

type Assets struct {
    assetref string `json:"ammount"`
    name string `json:"name"`
    qty float64 `json:"qty"`
}

var d = DecodedOffer{ask: make([]Ask, 0), offer: make([]Offer, 0)}