Trying to get balance of Tron wallet using tronscan.org

Sometimes Amount returns string, sometimes value like this

"amount": 1.4900288469458728E-8

When it returns value of this type i get this error json: cannot unmarshal number into Go struct field .Amount of type string

Here is my struct:

type trxResponse struct {
  Data []struct {
    Amount float64 `json:"amount,string"`
  } `json:"data"`
}

How can I handle it? To unmarshal json i'm using https://github.com/goccy/go-json

CodePudding user response：

As the amount field has different types, it can be declared as interface{} type, this will solve unmarshaling error.

type trxResponse struct {
  Data []struct {
    Amount interface{} `json:"amount"`
  } `json:"data"`
}

This can then be typecast from/to float64 or string as needed..

CodePudding user response：

You can implement the Unmarshaler interface by declaring custom UnmarshalJSON method, which will handle the amount field according to the type.

type trxData struct {
    Amount float64 `json:"amount"`
}

type trxResponse struct {
    Data []trxData `json:"data"`
}

// UnmarshalJSON custom method for handling different types
// of the amount field.
func (d *trxData) UnmarshalJSON(data []byte) error {
    var objMap map[string]*json.RawMessage

    // unmarshal json to raw messages
    err := json.Unmarshal(data, &objMap)
    if err != nil {
        return err
    }

    var amount float64 // try to unmarshal to float64
    if rawMsg, ok := objMap["amount"]; ok {
        if err := json.Unmarshal(*rawMsg, &amount); err != nil {
            // if failed, unmarshal to string
            var amountStr string
            if err := json.Unmarshal(*rawMsg, &amountStr); err != nil {
                return err
            }
            amount, err = strconv.ParseFloat(amountStr, 64)
            if err != nil {
                return err
            }
        }
    }

    d.Amount = amount

    return nil
}