Json Decode无法将json中的时间戳解析为Go结构

Question

我试图获取一个HTTP请求主体,它是一个json对象,并将其解码为我已定义的Go结构.

结构的两个字段是time.Time类型.虽然只有一个这样的类型字段,但一切正常.

如果我time.Time在go结构中有多个类型字段,我无法解码它并得到错误:

2014/11/01 01:07:04 parsing time "null" as ""2006-01-02T15:04:05Z07:00"": cannot parse "null" as """

问题出在解码线上.尽管我的调试努力,我本可以取得有意义的结果.这个问题似乎很奇怪,实际上不应该这样.

我在这里错过了什么？

func register(w http.ResponseWriter, r *http.Request){
//Read Request Body JSON Into Go Types

var requestBody = []byte(`{"username":"qwewwwqweqwe","password":"can","usertype":"student","firstname":"",??"midname":null,"surname":null,"signuptimestamp":null,"userstatus":null,"phone":nu??ll,"email":null,"address":null,"city":null,"country":null,"language":null,"lastlo??gintimestamp":null}`)

type RegisterStructure struct {
    Id int `json:"id"`
    Timestamp time.Time `json:"timestamp,omitemty"`
    SignupTimestamp time.Time `json:"signuptimestamp,omitempty"`
    Username string `json:"username"`
    Password string `json:"password"`
    UserType string `json:"usertype"`
    FirstName string `json:"firstname"`
    Midname string `json:"midname"`
    Surname string `json:"surname"`
    UserStatus string `json:"userstatus"`
    Phone string `json:"phone"`
    Email string `json:"email"`
    Address string `json:"address"`
    City string `json:"city"`
    Country string `json:"country"`
    Language string `json:"language"`
    //LastLoginTimestamp time.Time `json:"lastlogintimestamp,omitempty"`
}
var registerInstance RegisterStructure
var now = time.Now()
fmt.Printf("now is %v", now)
fmt.Println()
fmt.Printf("1 registerInstance after inited here is %v", registerInstance)
fmt.Println()

registerInstance = RegisterStructure{Timestamp: now, SignupTimestamp: now,}
fmt.Printf("registerInstance after set to var now here is %v", registerInstance)
fmt.Println()

dec := json.NewDecoder(bytes.NewReader(requestBody))
err = dec.Decode(&registerInstance)
if err != nil {
    fmt.Printf("error happens here.")
    log.Fatal(err)
}

Answer 1

好.这是一个可重现的示例,演示了您所看到的错误.

package main

import (
    "encoding/json"
    "fmt"
    "bytes"
    "time"
)

type RegisterStructure struct {
    SignupTimestamp time.Time `json:"signuptimestamp,omitempty"`
}

func main() {
    requestBody := []byte(`{"signuptimestamp" : null}`)
    dec := json.NewDecoder(bytes.NewReader(requestBody))
    registerInstance := RegisterStructure{}
    err := dec.Decode(&registerInstance)
    if err != nil {
        fmt.Println(err)
    }
}

您看到的错误与多个时间戳无关.这就是为什么显示输入对于调试此类情况至关重要的原因,以及为什么您应该返回并更改您的问题以将示例requestBody作为问题内容的一部分包含在内.否则,它变得非常难以猜测你在做什么.

发生了什么事情是null由JSON unmarshaller处理的time.Time.该文件对了time.time的解组说:UnmarshalJSON实现json.Unmarshaler接口.预计时间是RFC 3339格式的带引号的字符串.

null 不是这样的值:在这种情况下,解码器不会尝试为时间戳构造"零"值.

你想要做的是改变的类型SignupTimestamp,从time.Time到*time.Time,这样的null值可以明确地表示为nil指针.

这是一个示例:

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "time"
)

type RegisterStructure struct {
    SignupTimestamp *time.Time `json:"signuptimestamp,omitempty"`
}

func main() {
    requestBodies := []string{
        `{"signuptimestamp" : "1985-04-12T23:20:50.52Z"}`,
        `{"signuptimestamp" : null}`,
    }
    for _, requestBody := range requestBodies {
        dec := json.NewDecoder(bytes.NewReader([]byte(requestBody)))
        registerInstance := RegisterStructure{}
        err := dec.Decode(&registerInstance)
        if err != nil {
            fmt.Println(err)
        }
        fmt.Printf("%#v\n", registerInstance)
    }
}