doufan6544
2017-07-18 22:05
浏览 267
已采纳

Golang json从json转换int错误

I'm trying to do a simple unmarshall and extracting the int information from the code below. I found a link from another stackoverflow : link. Though, it doesn't help in my case. the program according to ideone think the data is a float.

package main
import "fmt"
import "encoding/json"

func main(){
    byt := []byte(`{"status": "USER_MOVED_LEFT", "id":1, "x":5, "y":3}`)
    var dat map[string]interface{}
    if err := json.Unmarshal(byt, &dat); err != nil {
        panic(err)
    }
    num := dat["id"].(int)
    fmt.Println(num)
}
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1条回答 默认 最新

  • doufan9377 2017-07-19 02:22
    已采纳

    If you are converting your byt to map[string]interfaec{} the default value of the number will be float64.

    func main(){
        byt := []byte(`{"status": "USER_MOVED_LEFT", "id":1, "x":5, "y":3}`)
        var dat map[string]interface{}
        if err := json.Unmarshal(byt, &dat); err != nil {
            panic(err)
        }
    
        fmt.Println(reflect.TypeOf(dat["id"])) // print the type of value
        num := dat["id"].(float64)
        fmt.Println(num)
    }
    

    But you can also change this behavior by converting your byt which is your data to a struct like this :

    type myStruct struct {
        Status string
        Id     int
        x      int
        y      int
    }
    
    func main() {
        byt := []byte(`{"status": "USER_MOVED_LEFT", "id":1, "x":5, "y":3}`)
        dat := myStruct{}
        if err := json.Unmarshal(byt, &dat); err != nil {
            panic(err)
        }
    
        fmt.Println(reflect.TypeOf(dat.Id))
        fmt.Printf("%+v
    ", dat.Id)
    
    }
    
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