douan8473
2016-12-17 05:18
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求助:解析POST请求中的req.body

我正在使用fetch API 将两个值发送到我的 POST 请求处理程序:

fetch('http://localhost:8080/validation', {
        method:'POST',
        headers: {
            'Accept': 'application/json',
            'Content-Type': 'application/json'
        },
        body: JSON.stringify({
            email:this.state.email,
            password:this.state.password
        })

我想在服务器端保存电子邮件和密码为字符串,以下是我的尝试:

type credentials struct {
    Test string
}

func Validate(rw http.ResponseWriter, req *http.Request, _ httprouter.Params) {

    decoder := json.NewDecoder(req.Body)

    var creds credentials

    err := decoder.Decode(&creds)

    if err != nil {
        panic(err)
    }

    fmt.Println(creds.Test)
}

问题是我不知道发送到 POST 结构的确切格式。我正在尝试将 req.Body 保存为字符串,但是没有得到任何结果。

当输入 fmt.Println 只得到一个空格,解析它的正确方法是什么?

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2条回答 默认 最新

  • drvkf88226 2016-12-17 05:41
    已采纳

    Try with

    type credentials struct {
        Email string `json:"email"`
        Password string `json:"password"`
    }
    

    You are receiving a JSON with two values. Receiving struct should have a structure matching your request. Otherwise, there are no placeholders to decode the JSON into, as in your case - email and password do not have matching struct fields. Btw. if you send "Test" in your JSON, this would work, as you have a Test field in your struct!

    Regarding field names. If fields in JSON do not start with a capital letter or even have different names, then you should use so called tags. More on tags: https://golang.org/pkg/encoding/json/#Marshal

    In my example I used them to match struct field names to your json fields, i.e. to make email from json match Email field of the credentials struct.

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  • dpysrta21239 2016-12-17 05:33

    req.Body is an io.Reader, and you can get use ioutil.ReadAll to drain it:

    data, err := ioutil.ReadAll(req.Body)
    asString := string(data) // you can convert to a string with a typecast
    

    But I'm not sure if that's what you meant by trying to save req.Body as a string.

    To parse the response into a data structure, you can unmarshal it into a variable of type *interface{}:

    var creds interface{}
    decoder.Decode(&creds)
    

    And then examine the value:

    fmt.Printf("%#v
    ", creds)
    

    Or perhaps using pp.Println(creds) which I find easier to read.

    The creds variable will represent the JSON object found in the body, for your example input this will be a map[string]interface{} with two entries, presumably both of them strings. Something like:

    map[string]interface{}{
        "email": email_value,
        "password": password_value,
    }
    

    and you check the values with:

    email, ok := creds["email"].(string)
    if ok {
        // email will contain the value because creds["email"] passed the type check
        fmt.Printf("submitted email is %#v
    ", email)
    } else {
        // "email" property was a string (may be missing, may be something else)
    }
    

    The documentation of json.Unmarshal explains the semantics of how arbitrary JSON strings can be parsed without knowing their structure in advance in the discussion about unmarshalling to interface values.

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