从非迭代 JSON 对象中获取值答案

【问题标题】：Fetch value from non-iterating JSON object从非迭代 JSON 对象中获取值
【发布时间】：2021-03-06 10:17:51
【问题描述】：

我有一个无法从中获取特定值的天气预报 JSON 对象。我正在尝试从下面的 json 中获取 weather_description。

JSON

{
    "request": {
        "type": "City",
        "query": "New York",
        "language": "en",
        "unit": "m"
    },
    "location": {
        "name": "New York",
        "country": "United States of America",
        "region": "New York",
        "lat": "40.714",
        "lon": "-74.006",
        "timezone_id": "America/New_York",
        "localtime": "2020-11-23 10:30",
        "localtime_epoch": 1606127400,
        "utc_offset": "-5.0"
    },
    "current": {
        "observation_time": "03:30 PM",
        "temperature": 11,
        "weather_code": 122,
        "weather_icons": [
            "https://assets.weatherstack.com/images/wsymbols01_png_64/wsymbol_0004_black_low_cloud.png"
        ],
        "weather_descriptions": [
            "Overcast"
        ],
        "wind_speed": 19,
        "wind_degree": 340,
        "wind_dir": "NNW",
        "pressure": 1014,
        "precip": 12,
        "humidity": 77,
        "cloudcover": 100,
        "feelslike": 8,
        "uv_index": 3,
        "visibility": 16,
        "is_day": "yes"
    }
}

HTML

<div>{{this.weatherData | keyvalue }}</div>

TS 文件

 getWeatherReport(data){
      this.weatherService.getWeatherReport(data.location).subscribe(
      data => {this.weatherData = data;    });

预期输出： 阴

实际输出： [对象对象],[对象对象],[对象对象]

【问题讨论】：

标签： html json angular typescript output

【解决方案1】：

KeyValue 管道符号不适用于您的情况。所以我们必须找到所需的密钥。由于 weather_descriptions 是一个数组，因此如果有多个元素，则使用循环。这是您想要的值的 Html 代码。

<div *ngIf="this.weatherData && this.weatherData.current && this.weatherData.current.weather_descriptions">
<span *ngFor= "let desc of this.weatherData.current.weather_descriptions">{{desc}}</span>
</div>

【讨论】：

现在得到预期的输出。但仍然在控制台窗口中收到以下错误 core.js:4442 ERROR TypeError: Cannot read property 'current' of undefined at DashboardComponent_Template (dashboard.component.html:9)
您可以在 div 上添加一些空检查验证。编辑了我的答案。