在 Node 中解析 JSON API答案

【问题标题】：Parsing a JSON API in Node在 Node 中解析 JSON API
【发布时间】：2014-02-11 22:56:46
【问题描述】：

我正在为外部 API 构建节点包装器，但在解析 JSON 响应时遇到问题。以下代码发出请求：

https = require "https"
querystring = require "querystring"

API_HOST = "api.lob.com"
API_PATH = "/v1"

startResponseHandler = (req, cb) ->
  if typeof cb isnt "function" then console.log "Error: callback needs to be a function!"
  req.on 'response', (res) ->
    response = ''
    res.setEncoding 'utf8'
    res.on 'data', (stream) ->
      response += stream
    res.on 'end', () ->
      error = null
      try
        response = JSON.parse response
        if res.statusCode != 200 or 201
          response = null
          error = new Error response.error.message
          error.name = response.error.type
          error.code = response.error.code
          error.param = response.error.param
      catch e
        error = new Error "Invalid JSON"
        response = null
      cb error, response
  req.on 'error', (error) ->
    cb error

module.exports = lob = (api_key) ->

  # This function makes the request
  makeRequest = (method, path, data, cb) ->
    data = querystring.stringify data
    options = 
      hostname: API_HOST
      path: "#{API_PATH}/#{path}"
      method: method
      auth: "#{api_key}:"
      headers:
        'Content-Type' : 'application/x-www-form-urlencoded'
        'Content-Length' : data.length
    req = https.request options
    startResponseHandler req, cb
    req.write data if method is "POST" or "PUT"
    req.end()

  # GET, POST, DELETE, PUT functions
  _get = (path, cb) ->
    makeRequest "GET", path, {}, cb

  _post = (path, data, cb) ->
    makeRequest "POST", path, data, cb

  _del = (path, cb) ->
    makeRequest "DELETE", path, {}, cb

  _put = (path, data, cb) ->
    makeRequest "PUT", path, data, cb

  # Jobs
  jobs:

    createJob: (data, cb) ->
      _post "/jobs/", data, cb

下面的代码是用来测试包装器的：

api_key = "test_0dc8d51e0acffcb1880e0f19c79b2f5b0cc"

lob     = require('../src/lob')(api_key)
should  = require("should")
chai    = require("chai")

data = 
  name: "Michigan fan letter"
  to: "adr_43769b47aed248c2"
  from: "adr_7f9ece71fbca3796"
  object1: "obj_7ca5f80b42b6dfca"
  object2: "obj_12128d3aad2aa98f"

describe "Job", ->
  @timeout(10000)
  describe "create", ->
    it "should create a job with address_id", (done) ->
      lob.jobs.createJob data , (new_job) ->
        new_job['name'].should.equal(data['name'])
        done()

但是，当我运行 mocha 测试 ($ mocha --compilers coffee:coffee-script) 时，我收到以下错误：

1) Job create should create a job with address_id:

      + expected - actual

      +"Michigan fan letter"
      -"Error"

编辑

以下是来自stream 内部res.on 'data' 的回复：

{
    "id": "job_7ecc50bea15178b8e07a",
    "name": "Michigan fan letter",
    "price": "1.26",
    "to": {
        "id": "adr_43769b47aed248c2",
        "name": "Harry Zhang",
        "email": "harry@lob.com",
        "phone": "5555555555",
        "address_line1": "123 Test Street",
        "address_line2": "Unit 199",
        "address_city": "Mountain View",
        "address_state": "CA",
        "address_zip": "94085",
        "address_country": "UNITED STATES",
        "date_created": "2013-07-20T05:53:25+00:00",
        "date_modified": "2013-07-20T05:53:25+00:00",
        "object": "address"
    },
    "from": {
        "id": "adr_7f9ece71fbca3796",
        "name": "Harry Zhang",
        "email": "harry@lob.com",
        "phone": "5555555555",
        "address_line1": "123 Test Avenue",
        "address_line2": "Unit 401",
        "address_city": "Seattle",
        "address_state": "WA",
        "address_zip": "98122",
        "address_country": "UNITED STATES",
        "date_created": "2013-07-20T05:55:19+00:00",
        "date_modified": "2013-07-20T05:55:19+00:00",
        "object": "address"
    },
    "status": "processed",
    "tracking": null,
    "packaging": {
        "id": "1",
        "name": "Smart Packaging",
        "description": "Automatically determined optimal packaging for safe and secure delivery",
        "object": "packaging"
    },
    "service": null,
    "objects": [
        {
            "id": "obj_7ca5f80b42b6dfca",
            "name": "Michigan is great",
            "quantity": "1",
            "full_bleed": "0",
            "double_sided": "0",
            "date_created": "2013-07-20T05:57:32+00:00",
            "date_modified": "2013-07-20T05:57:32+00:00",
            "setting": {
                "id": "101",
                "type": "Documents",
                "description": "Color Document",
                "paper": "20lb Paper Standard",
                "width": "8.500",
                "length": "11.000",
                "color": "Color",
                "notes": "50 cents per extra page",
                "object": "setting"
            },
            "url": "http://assets.lob.com/obj_7ca5f80b42b6dfca",
            "object": "object"
        },
        {
            "id": "obj_12128d3aad2aa98f",
            "name": "GO BLUE",
            "quantity": "1",
            "full_bleed": "0",
            "double_sided": "0",
            "date_created": "2013-07-31T00:58:35+00:00",
            "date_modified": "2013-07-31T00:58:35+00:00",
            "setting": {
                "id": "100",
                "type": "Documents",
                "description": "Black and White Document",
                "paper": "20lb Paper Standard",
                "width": "8.500",
                "length": "11.000",
                "color": "Black and White",
                "notes": "12 cents per extra page",
                "object": "setting"
            },
            "url": "http://assets.lob.com/obj_12128d3aad2aa98f",
            "object": "object"
        }
    ],
    "date_created": "2014-01-25T03:10:10+00:00",
    "date_modified": "2014-01-25T03:10:10+00:00",
    "object": "job"
}

与documentation 中的示例响应完全匹配

{
    "id": "job_754d8b14dd31587d6873",
    "name": "Michigan fan letter",
    "price": "0.96",
    "to": {
        "id": "adr_43769b47aed248c2",
        "name": "Harry Zhang",
        "email": "harry@lob.com",
        "phone": "5555555555",
        "address_line1": "123 Test Street",
        "address_line2": "Unit 199",
        "address_city": "Mountain View",
        "address_state": "CA",
        "address_zip": "94085",
        "address_country": "UNITED STATES",
        "date_created": "2013-07-20T05:53:25+00:00",
        "date_modified": "2013-07-20T05:53:25+00:00",
        "object": "address"
    },
    "from": {
        "id": "adr_7f9ece71fbca3796",
        "name": "Harry Zhang",
        "email": "harry@lob.com",
        "phone": "5555555555",
        "address_line1": "123 Test Avenue",
        "address_line2": "Unit 401",
        "address_city": "Seattle",
        "address_state": "WA",
        "address_zip": "98122",
        "address_country": "UNITED STATES",
        "date_created": "2013-07-20T05:55:19+00:00",
        "date_modified": "2013-07-20T05:55:19+00:00",
        "object": "address"
    },
    "status": "processed",
    "tracking": null,
    "packaging": {
        "id": "1",
        "name": "Smart Packaging",
        "description": "Automatically determined optimal packaging for safe and secure delivery",
        "object": "packaging"
    },
    "service": null,
    "objects": [
        {
            "id": "obj_7ca5f80b42b6dfca",
            "name": "Michigan is great",
            "quantity": "1",
            "full_bleed": "0",
            "double_sided": "0",
            "date_created": "2013-07-20T05:57:32+00:00",
            "date_modified": "2013-07-20T05:57:32+00:00",
            "setting": {
                "id": "101",
                "type": "Documents",
                "description": "Color Document",
                "paper": "20lb Paper Standard",
                "width": "8.500",
                "length": "11.000",
                "color": "Color",
                "notes": "50 cents per extra page",
                "object": "setting"
            },
            "object": "object"
        }
    ],
    "date_created": "2014-01-18T19:52:27+00:00",
    "date_modified": "2014-01-18T19:52:27+00:00",
    "object": "job"
}

这是来自JSON.parse response的数据

{ id: 'job_9973e060bd8147f97f5f',
  name: 'Michigan fan letter',
  price: '1.26',
  to:
   { id: 'adr_43769b47aed248c2',
     name: 'Harry Zhang',
     email: 'harry@lob.com',
     phone: '5555555555',
     address_line1: '123 Test Street',
     address_line2: 'Unit 199',
     address_city: 'Mountain View',
     address_state: 'CA',
     address_zip: '94085',
     address_country: 'UNITED STATES',
     date_created: '2013-07-20T05:53:25+00:00',
     date_modified: '2013-07-20T05:53:25+00:00',
     object: 'address' },
  from:
   { id: 'adr_7f9ece71fbca3796',
     name: 'Harry Zhang',
     email: 'harry@lob.com',
     phone: '5555555555',
     address_line1: '123 Test Avenue',
     address_line2: 'Unit 401',
     address_city: 'Seattle',
     address_state: 'WA',
     address_zip: '98122',
     address_country: 'UNITED STATES',
     date_created: '2013-07-20T05:55:19+00:00',
     date_modified: '2013-07-20T05:55:19+00:00',
     object: 'address' },
  status: 'processed',
  tracking: null,
  packaging:
   { id: '1',
     name: 'Smart Packaging',
     description: 'Automatically determined optimal packaging for safe and secure delivery',
     object: 'packaging' },
  service: null,
  objects:
   [ { id: 'obj_7ca5f80b42b6dfca',
       name: 'Michigan is great',
       quantity: '1',
       full_bleed: '0',
       double_sided: '0',
       date_created: '2013-07-20T05:57:32+00:00',
       date_modified: '2013-07-20T05:57:32+00:00',
       setting: [Object],
       url: 'http://assets.lob.com/obj_7ca5f80b42b6dfca',
       object: 'object' },
     { id: 'obj_12128d3aad2aa98f',
       name: 'GO BLUE',
       quantity: '1',
       full_bleed: '0',
       double_sided: '0',
       date_created: '2013-07-31T00:58:35+00:00',
       date_modified: '2013-07-31T00:58:35+00:00',
       setting: [Object],
       url: 'http://assets.lob.com/obj_12128d3aad2aa98f',
       object: 'object' } ],
  date_created: '2014-01-25T23:12:37+00:00',
  date_modified: '2014-01-25T23:12:37+00:00',
  object: 'job' }

【问题讨论】：

你看过stream 里面的res.on 'data' 看看它是否是你所期望的吗？ response 内部的 res.on 'end' 相同。
我没有记录内容，但返回了一个 201 标头，表明 POST 请求已成功发出
开始记录它，如果JSON.parse 抱怨，那么你可能没有得到你认为你得到的数据。
好建议！我已经用JSON.parse 的回复更新了这个问题
那是 JSON 字符串还是 JavaScript 对象？ JSON.parse 需要一个字符串。

标签： javascript json node.js coffeescript mocha.js

【解决方案1】：

我在该代码中发现了三个问题。我通常不使用 CoffeeScript。所以如果我看错了，请纠正我：

回调是这样调用的：
```
cb error, response
```
第一个参数是错误对象，第二个参数是响应，但是在测试中回调是这样的：
```
lob.jobs.createJob data , (new_job) ->
         new_job['name'].should.equal(data['name'])
```
所以new_job 是错误对象。然而，这并不能解释一切，因为您正在遇到错误。但是即使没有错误，new_job 的值也不会是响应。

测试显示字符串Error 是实际值的原因是Error 对象有一个name 字段，该字段设置为异常类的名称。（所以new Error().name 的计算结果为"Error"。）

这部分代码看起来也不正确：

try
  response = JSON.parse response
  if res.statusCode != 200 or 201
    response = null
    error = new Error response.error.message
    error.name = response.error.type
    error.code = response.error.code
    error.param = response.error.param
catch e
  error = new Error "Invalid JSON"
  response = null
cb error, response

在if 分支中，response 设置为null，然后访问response 的一些字段。这将导致异常。由于 try... catch 子句的设置方式，此异常将被解释为错误的 JSON。 try... catch 子句应缩小到仅涵盖 JSON.parse 调用：

try
  response = JSON.parse response
catch e
  error = new Error "Invalid JSON"
  response = null

这个测试不正确：
```
  if res.statusCode != 200 or 201
```
变成JavaScript：
```
  if (res.statusCode !== 200 || 201)
```
|| 之后的部分使其始终为真。类似于以下 CoffeeScript 代码的内容似乎是预期的：
```
  if res.statusCode not in [200, 201]
```

所以请求是否成功并不重要。因为第三个问题，if 测试总是为真，分支总是会被取走，第二个问题总是会出现。所以 Mocha 测试总是会失败。

【讨论】：

快速说明 - 使用此设置，如果我加入 console.log res.statusCode，它会返回 200
所以它不能解决你眼前的问题。很公平，但它仍然是糟糕的代码。
加上我添加的第三点，我可能已经涵盖了所有内容。