使用当前日期读取JSON并使用Javascript获取键值?

Question

我正在尝试从键中具有当前日期JSON响应中获取计数。

Json响应：

[
{
"type": {
"id": "mobile",
"name": "mobile",
"description": "",
"total_count": 0
},
"counts": [
{
"date": "2018-09-06",
"timestamp": 1536192000000,
"count": 20
},
{
"date": "2018-09-07",
"timestamp": 1536278400000,
"count": 10
}
]
},
{
"type": {
"id": "lap",
"name": "lap",
"description": "",
"total_count": 0
},
"counts": [
{
"date": "2018-09-06",
"timestamp": 1536192000000,
"count": 19
},
{
"date": "2018-09-07",
"timestamp": 1536278400000,
"count": 20
}
]
}
]

我的新尝试按照vikscool代码：

var json_count = JSON.parse(getcounts);
var curDate = getCurrentDate();
var mobilcount = () => json_count.map(ct => {
const count = ct.counts;
const getDate = count.find(dt => dt.date === curDate);
window.alert('count is ', getDate.count);
return {getDate};
});
mobilcount();
function getCurrentDate () {
var nowDate = new Date();
var month = (nowDate.getMonth() + 1).toString().length == 1
? '0' + (nowDate.getMonth() + 1)
: (nowDate.getMonth() + 1);
var day = nowDate.getDate().toString().length == 1
? '0' + nowDate.getDate()
: +nowDate.getDate();
return nowDate.getFullYear() + '-' + month + '-' + day;
}

输出："计数为">

但是没有从 JSON 打印的计数。

是否有任何解决方案Javascript我可以获取当前日期并获取计数。

我需要在移动计数中将计数为 10。

Answer 1

由于dates存储在名为json_count第一个对象的counts的JSON Array key中，因此无法使用以下命令获取它：

var instance_count=json_count[0].values[2].count;

由于您的 json 对象没有任何名为values的键。

您要做的是首先访问counts键，然后从中获取包含特定(在您的情况下为当前日期(的特定对象，然后从中获取计数。

下面是获取特定日期计数的示例代码：

//assuming this is the Json response you are getting as complete JSON response is not provided by the OP.
var getcounts = `[{"type":{"id":"mobile","name":"mobile","description":"","total_count":0},"counts":[{"date":"2018-09-05","timestamp":1533686400000,"count":0},{"date":"2018-09-06","timestamp":1533772800000,"count":8}]}]`;
//parsing the given json String 
var json_count = JSON.parse(getcounts);
function getCountForCurrentDate() {
var curDate = getCurrentDate(); //for which the data is to be fetched and making in format of the dates in JSON as yyyy-mm-dd
//finding the particular object that contains the current date
var searchedObj = json_count[0]['counts'].find(f => f['date'] == curDate);
if(searchedObj!==undefined)
console.log('count is', searchedObj['count']);
}
function getCurrentDate() {
var nowDate = new Date();
var month = (nowDate.getMonth() + 1).toString().length == 1 ? '0' + (nowDate.getMonth() + 1) : (nowDate.getMonth() + 1);
var day = nowDate.getDate().toString().length == 1 ? '0' + nowDate.getDate() : +nowDate.getDate();
return nowDate.getFullYear() + '-' + month + '-' + day;
}
getCountForCurrentDate();

在上面的代码片段中，我创建了两个函数getCurrentDate()以存储在响应JSON格式获取当前日期，getCountForCurrentDate()从json_count变量中获取count。

根据新要求，更新 1由OP提供

给定的JSON对象如下：

var json_count = [
{
type: {
id: "mobile",
name: "mobile",
description: "",
total_count: 0
},
counts: [
{
date: "2018-09-06",
timestamp: 1536192000000,
count: 20
},
{
date: "2018-09-07",
timestamp: 1536278400000,
count: 10
}
]
},
{
type: {
id: "lap",
name: "lap",
description: "",
total_count: 0
},
counts: [
{
date: "2018-09-06",
timestamp: 1536192000000,
count: 19
},
{
date: "2018-09-07",
timestamp: 1536278400000,
count: 20
}
]
}
];

现在，由于对象有两个实体，一个用于mobile，另一个用于lap我们可以获取特定值：

var mobile = json_count.find(f=>f['type']['id']=='mobile');//comparing the value present in the json object at location type.id to 'mobile' (change it to 'lap' or anything that is present in the id of the object).

现在为了获得它的计数，我们这样做：

var mobile_count = mobile.counts.find(f=>f['date']=='2018-09-07');//replace the static date with the date you want to fetch the count from 

，然后以以下方式访问count：

console.log(mobile_count.count);
//output:10