Question

我试图获取Json对象中'text'键的值，我通过twit库从GET请求获取到twitter。

我试图在数组上使用过滤器函数，因为我想进行函数式编程。

我可以在T.get函数的回调函数中使用json对象：

let results = data.statuses.filter(
    function(result){ return result.hasOwnProperty('text') 
})

然后我想只过滤每个状态上文本键的值，这是一个对象数组

所以我试过这个：

const Twit = require('twit')
const config = require('./config')
const T = new Twit(config)

let params  = { q: 'drum', count: 2 }

const gotData = function(err, data, response) {
  let results = data.statuses.filter(function(result){ return result.hasOwnProperty('text')})
  console.log(results)
}

T.get('search/tweets', params , gotData)

但是我收回了相同的数据。回到了......？

我想只得到对象上文本键的值，我做错了什么？

这是我的全部代码：

{ statuses:
   [ { created_at: 'Sun May 07 11:35:16 +0000 2017',
       id: 861182642888343600,
       id_str: '861182642888343552',
       text: '@was_going \nEvery hunk bore seven drums,\nEvery drum owned seven drums…',
       truncated: false,
       entities: [Object],
       metadata: [Object],
       source: '<a href="http://cheapbotsdonequick.com" rel="nofollow">Cheap Bots, Done Quick!</a>',
       in_reply_to_status_id: 861181362954489900,
       in_reply_to_status_id_str: '861181362954489856',
       in_reply_to_user_id: 795028044758949900,
       in_reply_to_user_id_str: '795028044758949888',
       in_reply_to_screen_name: 'was_going',
       user: [Object],
       geo: null,
       coordinates: null,
       place: null,
       contributors: null,
       is_quote_status: false,
       retweet_count: 0,
       favorite_count: 0,
       favorited: false,
       retweeted: false,
       lang: 'en' },
     { created_at: 'Sun May 07 11:35:09 +0000 2017',
       id: 861182610596405200,
       id_str: '861182610596405248',
       text: 'Would you rather have Data storage or A pedal assembly for a bass drum or high hat cymbals?',
       truncated: false,
       entities: [Object],
       metadata: [Object],
       source: '<a href="http://cheapbotsdonequick.com" rel="nofollow">Cheap Bots, Done Quick!</a>',
       in_reply_to_status_id: null,
       in_reply_to_status_id_str: null,
       in_reply_to_user_id: null,
       in_reply_to_user_id_str: null,
       in_reply_to_screen_name: null,
       user: [Object],
       geo: null,
       coordinates: null,
       place: null,
       contributors: null,
       is_quote_status: false,
       retweet_count: 0,
       favorite_count: 0,
       favorited: false,
       retweeted: false,
       lang: 'en' } ],
  search_metadata:
   { completed_in: 0.034,
     max_id: 861182642888343600,
     max_id_str: '861182642888343552',
     next_results: '?max_id=861182610596405247&q=drum&count=2&include_entities=1',
     query: 'drum',
     refresh_url: '?since_id=861182642888343552&q=drum&include_entities=1',
     count: 2,
     since_id: 0,
     since_id_str: '0' } }

这是我得到的Json响应的一个示例，它对应于gotData函数的数据：

 static double Q3(String stockFilename, String date) {

    // Given a filename with stock data in the format "date,price,volume" and a date, return the total value of all
    // shares of the stock that were traded that day. The total value is price times (multiplication) volume.

    String line = "";
    String dataArray[];
    double price = 0.0;
    double volume = 0.0;
    try {
        BufferedReader br = new BufferedReader(new FileReader(stockFilename));

        while ((line = br.readLine()) != null) {
            dataArray = line.split(",");

            if(dataArray[0].equals(date)) //Finds the date of that day
                price = Double.parseDouble(dataArray[1]); //Grabs price 
                volume = Double.parseDouble(dataArray[2]); //Grabs volume
        }

        br.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

    return price*volume;
}

Answer 1

您只需检查是否为文本属性。您可能还想将其映射到该属性：

let results = data.statuses.filter(
   result=>result.hasOwnProperty('text') 
).map(result=>result.text);

http://jsbin.com/niwezocuhu/edit?console

或者如果你注意表现（O（n）而不是O（n + n * r））：

let results= data.statuses.reduce((arr,result)=>(result.text&&arr.push(result.text)&&false)||arr,[]);

在使用具有有效条件的array.filter时获取相同的对象

1 个答案: