使用 https url 的 Javascript JSON 解析

Question

我正在尝试使用 url 获取 json 数据。现在我需要解析 Json 数据以仅从 url 获取提要数据。我正在添加下面的代码和 json 数据。任何人都可以帮助我怎么办解析来自以下 json 输出的提要数据。谢谢。

JSON 数据:

{
  "channel": {
    "id": 9,
    "name": "my_house",
    "description": "Netduino Plus connected to sensors around the house",
    "latitude": "40.44",
    "longitude": "-79.996",
    "field1": "Light",
    "field2": "Outside Temperature",
    "created_at": "2010-12-13T20:20:06-05:00",
    "updated_at": "2014-02-26T12:43:04-05:00",
    "last_entry_id": 6060625
  },
  "feeds": [{
    "created_at": "2014-02-26T12:42:49-05:00",
    "entry_id": 6060624,
    "field1": "188",
    "field2": "25.902335456475583"
  }, {
    "created_at": "2014-02-26T12:43:04-05:00",
    "entry_id": 6060625,
    "field1": "164",
    "field2": "25.222929936305732"
  }]
}

<小时/>

$.ajax({
  url: " https://api.thingspeak.com/channels/9/feeds.json?results=2",
  dataType: "json",
  cache: false,
  error: function(xhr, ajaxOptions, thrownError) {
    debugger;
    alert(xhr.statusText);
    alert(thrownError);
  },
  success: function(json1) {
    console.log(json1);
    if (json1.length == 0) {
      window.alert("The returned output array length is ZERO.");
    } else {
      var obj1, Feed;
      for (var x = 0; x < json1.length; x++) {
        obj1 = json1[x];
        console.log(obj1);
        if (obj1 == null || obj1 == "") {
          window.alert("\n The " + (x + 1) + "th object is NULL/BLANK.");
        } else {

          if (obj1.feeds == null || obj1.feeds.length == 0) {
            window.alert("\n The name portion of " + (x + 1) + "th object is NULL/BLANK.");
          } else {
            Feed = obj1.feeds;

            for (var k = 0; k < Feed.length; k++) {
              console.log("\n The deails of " + (x + 1) + "th Object are :  \nCreated_at: " + Feed[k].created_at + "\nEntry_id:" + Feed[k].entry_id + "\nField1:" + Feed[k].field1 + "\nField2:" + Feed[k].field2);
            }
          }
        }
      }
    }
  }
});

Answer 1

json1 不是数组，而是对象。您需要访问对象的 .feeds 属性才能获取 feed 数组。像这样的事情:

$.ajax({
  url: " https://api.thingspeak.com/channels/9/feeds.json?results=2",
  dataType: "json",
  cache: false,
  error: function(xhr, ajaxOptions, thrownError) {
    debugger;
    alert(xhr.statusText);
    alert(thrownError);
  },
  success: function(json) {
    console.log(json);
    if (!json || json.feeds === undefined || json.feeds.length === 0) {
      window.alert("The returned output array length is ZERO.");
    } else {
      json.feeds.forEach(function (feed, index) {
        var indexPlusOne = index + 1;
        console.log("The deails of " + indexPlusOne + "th Object are :  \nCreated_at: " + feed.created_at + "\nEntry_id:" + feed.entry_id + "\nField1:" + feed.field1 + "\nField2:" + feed.field2);
      });
    }
  }
});

如果使用 ES2015 和模板字符串，可以使其更具可读性:

$.ajax({
  url: " https://api.thingspeak.com/channels/9/feeds.json?results=2",
  dataType: "json",
  cache: false,
  error: (xhr, ajaxOptions, thrownError) => {
    debugger;
    alert(xhr.statusText);
    alert(thrownError);
  },
  success: (json) => {
    console.log(json);
    if (!json || json.feeds === undefined || json.feeds.length === 0) {
      window.alert("The returned output array length is ZERO.");
    } else {
      json.feeds.forEach(function (feed, index) {
        var indexPlusOne = index + 1;
        console.log(`
The deails of ${indexPlusOne}th Object are:
Created_at: ${feed.created_at}
Entry_id: ${feed.entry_id}
Field1: ${feed.field1}
Field2: ${feed.field2}`);
      });
    }
  }
});

除非您确实需要使用 cache 选项，否则我也会将其简化为仅使用 jQuery.getJSON 而不是 jQuery.ajax:

$.getJSON("https://api.thingspeak.com/channels/9/feeds.json?results=2")
  .fail((req, status, err) => {
    console.error(`AJAX call failed: ${err}`);
  })
  .done((data) => {
    console.log(data);
    if (!data || data.feeds === undefined || data.feeds.length === 0) {
      window.alert("The returned output array length is ZERO.");
    } else {
      data.feeds.forEach(function (feed, index) {
        var indexPlusOne = index + 1;
        console.log(`
The deails of ${indexPlusOne}th Object are:
Created_at: ${feed.created_at}
Entry_id: ${feed.entry_id}
Field1: ${feed.field1}
Field2: ${feed.field2}`);
      });
    }
  });