go - 将数据发布到端点后请求正文为空

Question

我不确定为什么在运行以下 curl 请求时发布的数据不存在:

curl --request POST http://localhost:4000 --header "Content-Type: application/json" --data '{ "hostname": "bbc.co.uk" }'

针对下面的代码。它本质上只是发布带有变量 hostname 的 json，但出于某种原因，它没有出现在 req.Body 中，也没有出现在 Domain 结构数组中。请注意这是基于 this tutorial

package main

import (
    "encoding/json"
    "log"
    "net/http"
    "fmt"

    "github.com/gorilla/mux"
    "github.com/gorilla/handlers"
)

type Domain struct {
    hostname string   `json:"hostname,omitempty"`
}

var domains []Domain

func CreateDomainEndpoint(w http.ResponseWriter, req *http.Request) {
    var domain Domain

    fmt.Println(req.Body)
    _ = json.NewDecoder(req.Body).Decode(&domain)
    domains = append(domains, domain)
    json.NewEncoder(w).Encode(domains)
}

func main() {
    router := mux.NewRouter()
    router.HandleFunc("/", CreateDomainEndpoint).Methods("POST")

    log.Fatal(http.ListenAndServe(":4000", handlers.CORS(handlers.AllowedHeaders([]string{"X-Requested-With", "Content-Type", "Authorization"}), handlers.AllowedMethods([]string{"GET", "POST", "PUT", "HEAD", "OPTIONS"}), handlers.AllowedOrigins([]string{"*"}))(router)))
}

Answer 1

• JSON 编解码器忽略 hostname 字段，因为该字段不是 exported .通过将字段名称大写来修复。
• 域 上存在数据竞争。通过使用 mutex 保护对变量的访问来修复.
• 应用程序忽略错误。通过检查并处理从 JSON 解码器返回的错误来修复。

这是修复后的代码:

package main

import (
    "encoding/json"
    "log"
    "net/http"
    "sync"

    "github.com/gorilla/handlers"
    "github.com/gorilla/mux"
)

type Domain struct {
    Hostname string `json:"hostname,omitempty"`
}

var (
    domains []Domain
    mu      sync.Mutex
)

func CreateDomainEndpoint(w http.ResponseWriter, req *http.Request) {
    var domain Domain
    if err := json.NewDecoder(req.Body).Decode(&domain); err != nil {
        http.Error(w, "bad request", 400)
        return
    }
    mu.Lock()
    domains = append(domains, domain)
    // To avoid holding the mutex while writing to the
    // response body, make a local copy of the slice header.
    d := domains
    mu.Unlock()

    json.NewEncoder(w).Encode(d)
}

func main() {
    router := mux.NewRouter()
    router.HandleFunc("/", CreateDomainEndpoint).Methods("POST")

    log.Fatal(http.ListenAndServe(":4000", handlers.CORS(handlers.AllowedHeaders([]string{"X-Requested-With", "Content-Type", "Authorization"}), handlers.AllowedMethods([]string{"GET", "POST", "PUT", "HEAD", "OPTIONS"}), handlers.AllowedOrigins([]string{"*"}))(router)))
}