英文:
Go send null in json
问题
在上面的代码中，我想在我的JSON字符串数组中发送null作为其中一个值。然而，上述代码无法编译，如果我给null添加双引号，它就变成了一个字符串，而不是null值。
在GO中，如何在JSON响应中发送null？
这篇文章似乎有所帮助，但看起来与我的问题相反。
英文:
type JobTitles struct {
Titles []string `json:"titles"`
}
chiefTitles := []string{"CEO", "CFO", null, "CMO"}
jsonOut := JobTitles{chiefTitles}
In the code above, I would like to be able to send null as one of the values in my json string array. However, the above will not compile and if I add double quotes to null it becomes a string not the value null.
How can I send null in my json response in GO?
This article seems to help, but looks to be the inverse of my question..
答案1
得分: 4
为了表示该类型的值为'null'，它必须是一个指针。问题不在于不能使用null，而是字符串不能具有该值。这是我在playground上制作的一个快速示例；https://play.golang.org/p/SXO5sBl2mR
package main
import "fmt"
import "encoding/json"
type Test struct {
A *string
B *string
}
func main() {
s := "Something"
t := Test{A:&s, B:nil}
b, err := json.Marshal(t)
if err != nil {
fmt.Println(err)
}
fmt.Println(string(b))
}
正如DaveC提到的，使用指针使初始化变得有点麻烦，但你可以使用我上面提到的相同类型的结构；声明一个字符串，使用&在复合字面量中引用该字符串。
英文:
In order to represent that type with the value 'null' it would have to be a pointer. The problem isn't that you can't use null but rather that a string can't have that value. Here is a quick example I made in the playground; https://play.golang.org/p/SXO5sBl2mR
package main
import "fmt"
import "encoding/json"
type Test struct {
A *string
B *string
}
func main() {
s := "Something"
t := Test{A:&s, B:nil}
b, err := json.Marshal(t)
if err != nil {
fmt.Println(err)
}
fmt.Println(string(b))
}
As DaveC mentioned using pointers makers the initilization a bit more cumbersome but you can use the same type of constructs I have above; declare a string, use the & that string in the composite literal.
答案2
得分: 3
你需要使用*string，并创建一个辅助函数来简化操作，类似于以下代码：
func main() {
chiefTitles := []*string{sP("CEO"), sP("CFO"), nil, sP("CMO")}
b, _ := json.Marshal(JobTitles{chiefTitles})
fmt.Println(string(b))
}
type JobTitles struct {
Titles []*string `json:"titles"`
}
func sP(s string) *string {
return &s
}
你可以在playground上运行这段代码。
英文:
You will have to use *string instead, and create a helper function to make it easier, something along the lines of:
func main() {
chiefTitles := []*string{sP("CEO"), sP("CFO"), nil, sP("CMO")}
b, _ := json.Marshal(JobTitles{chiefTitles})
fmt.Println(string(b))
}
type JobTitles struct {
Titles []*string `json:"titles"`
}
func sP(s string) *string {
return &s
}
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