如何使用Go提供JSON响应？

Question

问:目前我打印出我的回应func Index 是这样fmt.Fprintf(w, string(response)) 但是,我怎么能在请求发送正确的JSON,以便它可能由视图消耗？

package main

import (
    "fmt"
    "github.com/julienschmidt/httprouter"
    "net/http"
    "log"
    "encoding/json"
)

type Payload struct {
    Stuff Data
}
type Data struct {
    Fruit Fruits
    Veggies Vegetables
}
type Fruits map[string]int
type Vegetables map[string]int


func Index(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
    response, err := getJsonResponse();
    if err != nil {
        panic(err)
    }
    fmt.Fprintf(w, string(response))
}


func main() {
    router := httprouter.New()
    router.GET("/", Index)
    log.Fatal(http.ListenAndServe(":8080", router))
}

func getJsonResponse()([]byte, error) {
    fruits := make(map[string]int)
    fruits["Apples"] = 25
    fruits["Oranges"] = 10

    vegetables := make(map[string]int)
    vegetables["Carrats"] = 10
    vegetables["Beets"] = 0

    d := Data{fruits, vegetables}
    p := Payload{d}

    return json.MarshalIndent(p, "", "  ")
}

Answer 1

您可以设置内容类型标题,以便客户知道期望json

w.Header().Set("Content-Type", "application/json")

将结构编组为json的另一种方法是使用.来构建编码器 http.ResponseWriter

// get a payload p := Payload{d}
json.NewEncoder(w).Encode(p)

Answer 2

其他用户评论的Content-Type是plain/text编码时.您必须设置第Content-Type一个w.Header().Set,然后是HTTP响应代码w.WriteHeader.

如果你w.WriteHeader先打电话w.Header().Set,然后打电话给你plain/text.

示例处理程序可能如下所示;

func SomeHandler(w http.ResponseWriter, r *http.Request) {
    data := SomeStruct{}
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(http.StatusCreated)
    json.NewEncoder(w).Encode(data)
}

Answer 3

你可以在你的getJsonResponse功能中做这样的事情-

jData, err := json.Marshal(Data)
if err != nil {
    // handle error
}
w.Header().Set("Content-Type", "application/json")
w.Write(jData)