英文:
How to display all data from a map in json format - Golang?
问题
我正在使用golang创建一个API，它将以JSON格式简单地显示来自map的所有数据。
端点：/keys
type UserController struct{}
// NewUserController函数
func NewUserController() *UserController {
return &UserController{}
}
// Data结构体
type Data struct {
Datakey int `json:"key"`
Datavalue string `json:"value"`
}
var datamap = make(map[int]string)
func (uc UserController) getallkeys(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
type Users []Data
var uj Users
for k, v := range datamap {
uj = append(uj, Data{
Datakey: k,
Datavalue: v,
})
}
result, _ := json.Marshal(uj)
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(200)
fmt.Fprintf(w, "%s", result)
}
例如：
响应应该类似于
[
{
"key": somekey,
"value": "somevalue"
},
{
"key": somekey,
"value": "somevalue"
}
]
我不清楚如何实现这个。上面的代码只显示了map中的最后一个数据。这是不正确的，但我不确定如何继续。如果有人能帮助我，那就太好了。
谢谢。
英文:
I am creating a API in golang which will simply display all data from a map in json format.
endpoint: /keys
type UserController struct{}
// NewUserController function
func NewUserController() *UserController {
return &UserController{}
}
// Data struct
type Data struct {
Datakey int `json:"key"`
Datavalue string `json:"value"`
}
var datamap = make(map[int]string)
func (uc UserController) getallkeys(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
type Users []Data
var uj Users
for k, v := range datamap {
uj = Users{
Data{
Datakey: k,
Datavalue: v,
},
}
}
result, _ := json.Marshal(uj)
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(200)
fmt.Fprintf(w, "%s", result)
}
For eg:
The response should be something like
[
{
"key":somekey,
"value":"somevalue"
},
{
"key":somekey,
"value":"somevalue"
}
]
I am not clear how to implement this. The above code is displaying just the last data from the map. This is incorrect but I am not sure how to proceed. It would be great if someone could help me with this.
Thanks.
答案1
得分: 1
至少有两个不同的问题。
首先，一个 JSON Map 不能有一个 int 键。这是 JSON 规范的一部分。要么将其更改为字符串，要么您将不得不为该映射实现 MarshalJSON 和 UnmarshalJSON 接口，即为类型
type MyMap map[int]string
Google golang UnmarshalJSON time.Duration 以获取一些基本示例。还要注意映射和您特定的键类型。
其次，对于切片类型
type Users []Data
添加元素需要使用 append
uj := make(Users,0)
for k, v := range datamap {
d := Data{k,v}
uj = append(uj, d)
}
当然，将切片编组为一个无键的 JSON Map -- 这可能不是您想要的结果。
英文:
At least two different problems.
First, a JSON Map cannot have an `int' key. That is part of the JSON spec. Either change it to a string or you will have to implement the MarshalJSON and UnmarshalJSON interfaces for the map, i.e, for the type
type MyMap map[int]string
Google golang UnmarshalJSON time.Duration for a number of basic examples. Also, against map and your specific key type.
Second, for a slice type
type Users []Data
adding elements requires append
uj := make(Users,0)
for k, v := range datamap {
d := Data{k,v}
uj = append(uj, d)
}
Of course, marshaling a slice produces a keyless JSON map -- likely not what you want.
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