英文:
Using JSON requests in Google App Engine (Go programming language)
问题
我正在尝试从我的应用程序的Javascript前端以JSON格式向App Engine发送请求，使用Go语言。我应该如何将请求解析为处理程序中的结构体？
举个例子，假设我的请求是一个带有请求有效负载的POST请求：
{'Param1':'Value1'}
而我的结构体是：
type Message struct {
Param1 string
}
以及变量：
var m Message
在App Engine文档中的示例中，使用FormValue函数来获取标准请求值，但是当你使用JSON时，这种方法似乎不起作用。
非常感谢提供一个简单的示例。
英文:
I am trying to send requests in JSON format from the Javascript front-end of my application to App Engine using Go. How do I parse the request to a struct in the handler?
Say for example my request is a POST with the request payload
{'Param1':'Value1'}
and my struct is
type Message struct {
Param1 string
}
and the variable
var m Message
The examples in the app engine documentation use the FormValue function for getting standard request values, and this doesn't seem to work when you use json.
A simple example would be greatly appreciated.
答案1
得分: 5
官方文档非常好，可以参考：
http://golang.org/doc/articles/json_and_go.html
它提供了编码/解码到已知结构的示例（您的示例），还展示了如何使用反射来完成，类似于您通常在脚本语言中所做的方式。
英文:
The official documentation is pretty good, see:
http://golang.org/doc/articles/json_and_go.html
It has examples both for encoding/decoding to a known structure (your example), but also shows how to do it using reflection, similar to how you would typically do it in more scripty languages.
答案2
得分: 1
你可以将数据发送到一个表单字段中，但通常你只需要从response.Body中读取它。这是一个最简单的jQuery和App Engine示例：
package app
import (
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"strings"
)
func init () {
http.HandleFunc("/", home)
http.HandleFunc("/target", target)
}
const homePage =
`<!DOCTYPE html>
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
</head>
<body>
<form action="/target" id="postToGoHandler">
<input type="submit" value="Post" />
</form>
<div id="result"></div>
<script>
$("#postToGoHandler").submit(function(event) {
event.preventDefault();
$.post("/target", JSON.stringify({"Param1": "Value1"}),
function(data) {
$("#result").empty().append(data);
}
);
});
</script>
</body>
</html>`
func home(w http.ResponseWriter, r *http.Request) {
fmt.Fprint(w, homePage)
}
type Message struct {
Param1 string
}
func target(w http.ResponseWriter, r *http.Request) {
defer r.Body.Close()
if body, err := ioutil.ReadAll(r.Body); err != nil {
fmt.Fprintf(w, "Couldn't read request body: %s", err)
} else {
dec := json.NewDecoder(strings.NewReader(string(body)))
var m Message
if err := dec.Decode(&m); err != nil {
fmt.Fprintf(w, "Couldn't decode JSON: %s", err)
} else {
fmt.Fprintf(w, "Value of Param1 is: %s", m.Param1)
}
}
}
英文:
You could send the data in a form field, but typically you'll just read it from the response.Body. Here's a minimal jQuery & App Engine example:
package app
import (
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"strings"
)
func init () {
http.HandleFunc("/", home)
http.HandleFunc("/target", target)
}
const homePage =
`<!DOCTYPE html>
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
</head>
<body>
<form action="/target" id="postToGoHandler">
<input type="submit" value="Post" />
</form>
<div id="result"></div>
<script>
$("#postToGoHandler").submit(function(event) {
event.preventDefault();
$.post("/target", JSON.stringify({"Param1": "Value1"}),
function(data) {
$("#result").empty().append(data);
}
);
});
</script>
</body>
</html>`
func home(w http.ResponseWriter, r *http.Request) {
fmt.Fprint(w, homePage)
}
type Message struct {
Param1 string
}
func target(w http.ResponseWriter, r *http.Request) {
defer r.Body.Close()
if body, err := ioutil.ReadAll(r.Body); err != nil {
fmt.Fprintf(w, "Couldn't read request body: %s", err)
} else {
dec := json.NewDecoder(strings.NewReader(string(body)))
var m Message
if err := dec.Decode(&m); err != nil {
fmt.Fprintf(w, "Couldn't decode JSON: %s", err)
} else {
fmt.Fprintf(w, "Value of Param1 is: %s", m.Param1)
}
}
}
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