如何比较两个JSON请求? [英] How to compare two JSON requests?

问题描述

短篇小说:如何比较两个JSON块?下面的代码出错了.

Short Story: How can I compare two chunks of JSON? The code below errors out.

var j, j2 interface{}
b := []byte(srv.req)
if err := json.Unmarshal(b, j); err !=nil{
    t.Errorf("err %v, req %s", err, b)
    return
}
d := json.NewDecoder(r.Body)
if err := d.Decode(j2); err !=nil{
    t.Error(err)
    return
}
if !reflect.DeepEqual(j2, j){
    t.Errorf("j %v, j2 %v", j, j2)
    return
}

长篇故事: 我正在进行一些E2E测试，其中一部分需要将请求的JSON正文与接收到的JSON进行比较.为此，我尝试将期望的接收到的json解组到一个空接口(以避免任何类型错误)，但出现错误: json: Unmarshal(nil).我猜编码/json不喜欢空接口，所以问题是如何比较两个JSON块?字符串比较会容易出错，所以我试图避免这种情况.

Long Story: I'm doing some E2E testings and part of this I need to compare the requested JSON body with the received JSON. To do this I've tried to unmarshal the expected and received json to an empty interface (to avoid any type mistakes) but I get an error: json: Unmarshal(nil). I guess encoding/json doesn't like the empty interface so the question is how can I compare two chunks of JSON? A string comparison would be error prone so I'm trying to avoid that.

推荐答案

您需要将指针传递给Decode和Unmarshal.我用func JSONEqual(a, b io.Reader)和JSONBytesEqual(a, b []byte)放置了可运行示例，都返回了(bool, error).您可以使用bytes.NewBuffer或strings.NewReader包装您的期望内容，从而将请求正文与您的静态期望内容进行比较(就像您要在问题中尝试做的那样).这是代码:

You need to pass pointers to Decode and Unmarshal. I put up a runnable sample with func JSONEqual(a, b io.Reader) and JSONBytesEqual(a, b []byte), both returning (bool, error). You can compare a request body to your static expected content (like you're trying to do in the question) by wrapping your expected content using bytes.NewBuffer or strings.NewReader. Here's the code:

package main

import (
    "encoding/json"
    "fmt"
    "io"
    "reflect"
)

// JSONEqual compares the JSON from two Readers.
func JSONEqual(a, b io.Reader) (bool, error) {
    var j, j2 interface{}
    d := json.NewDecoder(a)
    if err := d.Decode(&j); err != nil {
        return false, err
    }
    d = json.NewDecoder(b)
    if err := d.Decode(&j2); err != nil {
        return false, err
    }
    return reflect.DeepEqual(j2, j), nil
}

// JSONBytesEqual compares the JSON in two byte slices.
func JSONBytesEqual(a, b []byte) (bool, error) {
    var j, j2 interface{}
    if err := json.Unmarshal(a, &j); err != nil {
        return false, err
    }
    if err := json.Unmarshal(b, &j2); err != nil {
        return false, err
    }
    return reflect.DeepEqual(j2, j), nil
}

func main() {
    a := []byte(`{"x": ["y",42]}`)
    b := []byte(`{"x":                  ["y",  42]}`)
    c := []byte(`{"z": ["y", "42"]}`)
    empty := []byte{}
    bad := []byte(`{this? this is a test.}`)

    eq, err := JSONBytesEqual(a, b)
    fmt.Println("a=b\t", eq, "with error", err)
    eq, err = JSONBytesEqual(a, c)
    fmt.Println("a=c\t", eq, "with error", err)
    eq, err = JSONBytesEqual(a, empty)
    fmt.Println("a=empty\t", eq, "with error", err)
    eq, err = JSONBytesEqual(a, bad)
    fmt.Println("a=bad\t", eq, "with error", err)
}

它输出:

a=b  true with error <nil>
a=c  false with error <nil>
a=empty  false with error EOF
a=bad    false with error invalid character 't' looking for beginning of object key string

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