Print value from JSON file in Go

Question

I am making a currency converter in Go which downloads a JSON file and it then reads it to print the current currency rate. I am unable to understand how to print the value, I know I have to use Unmarshal but I don't understand how to use it.

For example I want to print the value 1.4075 from the JSON file.

Here is the JSON file (This is pulled from here):

{"base":"GBP","date":"2016-04-08","rates":{"USD":1.4075}}

Here is what I have done so far.

package main
import(
 "encoding/json"
 "fmt"
 "io/ioutil"
)
func main(){
 fromCurrency:="GBP"
 toCurrency:="USD"
 out, err := os.Create("latest.json")
 if err != nil{
 fmt.Println("Error:", err)
 }
 defer out.Close()
 resp, err := http.Get("http://api.fixer.io/latest?base=" + fromCurrency + "&symbols=" + toCurrency)
 defer resp.Body.Close()
 _, err = io.Copy(out, resp.Body)
 if err!= nil{
 fmt.Println("Error:", err)
 }
}

Answer 1

Decode the response to a type that matches the shape of the response. For example:

var data struct {
 Base string
 Date string
 Rates map[string]float64
}
if err := json.NewDecoder(resp.Body).Decode(&data); err != nil {
 log.Fatal(err)
}

Print the the appropriate value:

if r, ok := data.Rates["USD"]; ok {
 log.Println("Rate", r)
} else {
 log.Println("no rate")
}

complete example

• Lakhan Mankani: Thank you very much. This is right what I was looking for!