Question

我知道有很多主题都有同样的问题，但我很困惑。

我想遍历我的对象属性并写入值。

但我见过的所有内容都说

const clone = require('clone')

let db = {}

const defaultData = {
  "8xf0y6ziyjabvozdd253nd": {
    id: '8xf0y6ziyjabvozdd253nd',
    timestamp: 1467166872634,
    title: 'Udacity is the best place to learn React',
    body: 'Everyone says so after all.',
    author: 'thingtwo',
    category: 'react',
    voteScore: 6,
    deleted: false,
    commentCount: 2
  },
  "6ni6ok3ym7mf1p33lnez": {
    id: '6ni6ok3ym7mf1p33lnez',
    timestamp: 1468479767190,
    title: 'Learn Redux in 10 minutes!',
    body: 'Just kidding. It takes more than 10 minutes to learn technology.',
    author: 'thingone',
    category: 'redux',
    voteScore: -5,
    deleted: false,
    commentCount: 0
  }
}

function getData (token) {
  let data = db[token]
  if (data == null) {
    data = db[token] = clone(defaultData)
  }
  return data
}

function getByCategory (token, category) {
  return new Promise((res) => {
    let posts = getData(token)
    let keys = Object.keys(posts)
    let filtered_keys = keys.filter(key => posts[key].category === category && !posts[key].deleted)
    res(filtered_keys.map(key => posts[key]))
  })
}

function get (token, id) {
  return new Promise((res) => {
    const posts = getData(token)
    res(
      posts[id].deleted
        ? {}
        : posts[id]
    )
  })
}

function getAll (token) {
  return new Promise((res) => {
    const posts = getData(token)
    let keys = Object.keys(posts)
    let filtered_keys = keys.filter(key => !posts[key].deleted)
    res(filtered_keys.map(key => posts[key]))
  })
}

function add (token, post) {
  return new Promise((res) => {
    let posts = getData(token)

    posts[post.id] = {
      id: post.id,
      timestamp: post.timestamp,
      title: post.title,
      body: post.body,
      author: post.author,
      category: post.category,
      voteScore: 1,
      deleted: false,
      commentCount: 0
    }

    res(posts[post.id])
  })
}

function vote (token, id, option) {
  return new Promise((res) => {
    let posts = getData(token)
    post = posts[id]
    switch(option) {
        case "upVote":
            post.voteScore = post.voteScore + 1
            break
        case "downVote":
            post.voteScore = post.voteScore - 1
            break
        default:
            console.log(`posts.vote received incorrect parameter: ${option}`)
    }
    res(post)
  })
}

function disable (token, id) {
    return new Promise((res) => {
      let posts = getData(token)
      posts[id].deleted = true
      res(posts[id])
    })
}

function edit (token, id, post) {
    return new Promise((res) => {
        let posts = getData(token)
        for (prop in post) {
            posts[id][prop] = post[prop]
        }
        res(posts[id])
    })
}

function incrementCommentCounter(token, id, count) {
  const data = getData(token)
  if (data[id]) {
    data[id].commentCount += count
  }
}

module.exports = {
  get,
  getAll,
  getByCategory,
  add,
  vote,
  disable,
  edit,
  getAll,
  incrementCommentCounter
}

这将创建一个包含属性信息的数组，但它不存储该object.property的实际值，

该物业的名称是自动收报机，但Mycompanies（1）.ticker的价值是AMZN。

我的代码：

        Dim pinfo() As PropertyInfo = MyCompanies(1).GetType().GetProperties()

注意：MyCompanies（1）只是对象数组中的第二个对象，所有对象都属于公司类

https://msdn.microsoft.com/en-us/library/b05d59ty(v=vs.110).aspx也没有帮助。这让我相信我应该这样做：

 Dim pinfo() As PropertyInfo = MyCompanies(1).GetType().GetProperties()

 'Loop through Properties 
 For pi = 0 To pinfo.Length - 1
        'I want to get the values of each property
        Console.WriteLine(?)
    Next pi

但是，甚至不会建立。是因为我试图通过使用数组中的位置来赋予它对象吗？

...在这个循环之外我将不得不遍历我的对象数组，所以我想我可以用一个i替换1 ...

Answer 1

你应该这样打电话：

Dim props As PropertyInfo() = MyCompanies(1).GetType().GetProperties()

注意GetProperties返回一个PropertyInfo数组 - 一个代表每个属性。

然后，循环：

For Each prop in props
    Console.WriteLine(prop.GetValue(MyCompanies(1)).ToString())
Next

请注意，PropertyInfo类不包含对您从中派生类型信息的特定对象的引用（这就是您不能只调用prop.GetValue()的原因）。

它只是一种描述有问题的类型的模板 - 因此你必须向它传递一个对你想要提取其属性值的实际对象的引用。

如果您正在访问多个MyCompanies对象，那么您只需获取一次类型信息，然后重复使用它。

例如：

Dim props As PropertyInfo() = MyCompanies(1).GetType().GetProperties()

For Each company in MyCompanies

    Console.WriteLine(company.ToString()) 'e.g. to print the company name

    For Each prop in props
        Console.WriteLine(prop.GetValue(company).ToString())
    Next
Next

我还没有对代码进行测试，所以可以原谅任何小问题。

循环访问对象属性的值？

1 个答案: