将 URL.Query（切片映射）转换为 struct golang

Question

如果能从标准库 URL.Query() 直接映射到结构体，那就太棒了。

Query() 返回如下地图： map[a:[aaaa] b:[bbbb] c:[cccc]]

结构如下：

type Thing struct {
    A    string
    B    string
    C    string
}

• 我不知道为什么 URL.Query 会返回一个包含数组元素的映射。 （嗯..我知道why 但GET 不太可能有重复的参数）

Answer 1

请在下面找到直接在 golang 结构中解析 get 查询参数然后将结构作为响应发送回来的完整示例

package main

import (
    "log"
    "net/http"
    "encoding/json"
    "github.com/gorilla/schema"
)

var decoder  = schema.NewDecoder()

type EmployeeStruct struct {
    MemberId         string `schema:"memberId"`
    ActivityType     string `schema:"activityType"`
    BusinessUnitCode int    `schema:"businessUnitCode"`
}

func GetEmployee(w http.ResponseWriter, r *http.Request) {
    var employeeStruct EmployeeStruct

    err := decoder.Decode(&employeeStruct, r.URL.Query())
    if err != nil {
        log.Println("Error in GET parameters : ", err)
    } else {
        log.Println("GET parameters : ", employeeStruct)
    }

    w.Header().Set("Content-Type", "application/json")
    json.NewEncoder(w).Encode(employeeStruct)
}

func main() {
    mux := http.NewServeMux()
    mux.HandleFunc("/GetEmployee", GetEmployee)
    log.Fatal(http.ListenAndServe(":8080", mux))
}

执行和测试的步骤（假设您将上述代码保存在 employee.go 中）：

第一步：运行employee.go

第二步：在浏览器中打开http://localhost:8080/GetEmployee?memberId=123&activityType=Call&businessUnitCode=56

第 3 步：您应该在浏览器窗口中得到以下响应

{
    "MemberId": "123",
    "ActivityType": "Call",
    "BusinessUnitCode": 56
}

第 4 步：在控制台上，您应该会看到以下内容

GET parameters :  {123 Call 56}

Answer 2

示例：

filters={"reference":["docker.io/library/alpine:latest"]}

需要将网址编码为：

filters=%7B%22reference%22%3A%5B%22docker.io%2Flibrary%2Falpine%3Alatest%22%5D%7D

并且可以使用"github.com/gorilla/schema"

    query := struct {
        All     bool
        Filters map[string][]string `schema:"filters"`
        Digests bool
        Filter  string 
    }{}
    decoder := schema.NewDecoder()
    decoder.Decode(&query, r.URL.Query())

Answer 3

正如@mh-cbon 所指出的，gorilla schema 是这里的终极解决方案。

而不是从 URL 属性中获取 queryParams。

func handleRequest(w http.ResponseWriter, r *http.Request) {
    queryString := r.URL.Query()
    //...parsing the Values -> map[string][]string
}

gorilla 模式的方法是将r.PostForm 发送到解码函数。

func handleRequest(w http.ResponseWriter, r *http.Request) {
    err := decoder.Decode(person, r.PostForm)
    //...using reflect each struct's property can be called using 
    // the PostForm(url string, data url.Values) signature

    fmt.Print(person.GoodJobGorilla)
}

Answer 4

我写了一个 Go 包 ggicci/httpin 专门用于解决这个问题。不仅用于查询，还可以解码来自 HTTP 标头的数据。这是一个例子：

type Authorization struct {
    // Decode from multiple sources, the former with higher priority
    Token string `in:"form=access_token;header=x-api-token;required"`
}

type Pagination struct {
    Page int `in:"form=page"`

    // Decode from multiple keys in the same source, the former with higher priority
    PerPage int `in:"form=per_page,page_size"`
}

type ListUsersInput struct {
    Gender   string `in:"form=gender"`
    AgeRange []int  `in:"form=age_range"`
    IsMember bool   `in:"form=is_member"`

    Pagination    // Embedded field works
    Authorization // Embedded field works
}

func ListUsers(rw http.ResponseWriter, r *http.Request) {
    inputInterface, err := httpin.New(ListUsersInput{}).Decode(r)
    if err != nil {
        // Error occurred, `err` can be type of *httpin.InvalidFieldError
        // Do sth.
        return
    }

    input := interfaceInput.(*ListUsersInput)
    // Do sth.
}

我确实希望这个库可以节省大家用 Go 编写 API 的时间。

Answer 5

你可以使用Echo的优雅包。

我写了一些代码作为例子，带有不言自明的cmets

 package main

 import (
     "log"
     "github.com/labstacks/echo"
)

// Declare your struct with form: "" tag
type Employee struct {
    MemberId         string `form:"memberId"`
    ActivityType     string `form:"activityType"`
    BusinessUnitCode int    `form:"businessUnitCode"`
}

// Your handlers should look like this method 
// Which takes an echo.Context and returns an error
func GetEmployee(ctx echo.Context) error{
    var employee Employee
    // With Bind, you can get the Post Body or query params from http.Request
    // that is wrapped by echo.Context here 
    if err := ctx.Bind(&employee);err != nil {
        return err
    } 

    // now you can use your struct , e.g
    return ctx.json(200, employee.MemberId)
}

// now use the handler in your main function or anywhere you need
func main() {
    e := echo.New()
    e.Get("/employee", GetEmployee)
    log.Fatal(e.Start(":8080"))
}

Answer 6

只需将字符串解析为 URL，然后您就可以使用 lib github.com/gorilla/schema 对其进行解析:)

// Example to parse querystring to struct
package main

import (
    "log"
    "net/url"

    "github.com/gorilla/schema"
)

type URLParams struct {
    Code  string `schema:"code"`
    State string `schema:"state"`
}

func main() {
    var (
        params  URLParams
        decoder = schema.NewDecoder()
    )
    p := "https://www.redirect-url.com?code=CODE&state=RANDOM_ID"

    u, _ := url.Parse(p)

    err := decoder.Decode(&params, u.Query())
    if err != nil {
        log.Println("Error in Decode parameters : ", err)
    } else {
        log.Printf("Decoded parameters : %#v\n", params)
    }
}

https://go.dev/play/p/CmuPhdKh6Yg