英文:
golang json encoding return {} for an empty map
问题
我正在尝试让json.Marshal返回{"map": {}}而不是{"map":null}，但是encoding/json似乎检测到这是一个空映射，并且只返回后者的值。
我尝试过手动初始化映射并使用引用，但都没有得到我想要的输出。你有什么建议吗？
英文:
I am trying to get go to actually return me something like this:
{"map": {}} not {"map":null} but the encoding/json seems to detect that this is an empty map and only return the latter value.
type test struct {
MyMap map[string]string `json:"map"`
}
func main() {
testval := test{}
asjson, err := json.Marshal(testval)
fmt.Println(testval)
fmt.Println(string(asjson))
}
The output is like this
{map[]}
{"map":null}
I am looking to get it to be {"map":{}} suggestions? I have tried to initialize the map manually, and use a reference for it. Neither seems to yield the output I want. :/
答案1
得分: 16
test.MyMap尚未初始化，因此它是nil。初始化它将给你所期望的结果：
testval := test{
MyMap: make(map[string]string),
}
https://play.golang.org/p/91vZtJeot3
英文:
test.MyMap hasn't been initialized, so it is nil. Initializing it will give you the desired result:
testval := test{
MyMap: make(map[string]string),
}
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