Question

我试图将数据传递到在组件内部声明的数组，但是我只获得了数组的第一个索引，其他元素没有返回。

我读到程序异步工作，并且只获取第一个索引，而且他们建议在for循环中更改var i，让ı对其进行更改。

组件：

 weathers: Weather[] = [{adress:'',city:''}];
 weather: Weather;
 constructor(private weatherService: WeatherService) {
 }
 ngOnInit() {
 this.weatherService.getWeather().subscribe(weathers =>
{
  let size = (Object).keys(weathers).length;
  this.weathers =  Weather[size] = [{adress:'',city:''}];
  console.log(weathers);
  console.log(size);
    for(let i=0;i<size;i++) {
     const adress = weathers[i].adress;
     const city = weathers[i].city;
     this.weathers[i].adress=adress;
     this.weathers[i].city=city;
   }


  }
);
}

服务：

export class WeatherService {
weatherList: Weather[];
constructor(private http: HttpClient) { }
getWeather() {
return this.http.get<Weather>('/api/weathers');
}
}

班级：

  export class Weather {
  city: string;
  adress: string;
   }

ERROR TypeError：

Cannot set property 'adress' of undefined
at SafeSubscriber._next (weather.component.ts:31)
at SafeSubscriber.__tryOrUnsub (Subscriber.js:185)
at SafeSubscriber.next (Subscriber.js:124)

Answer 1

您不应该这样使用数组：this.weathers = Weather[size] = [{adress:'',city:''}];。制作时无需设置数组的大小：

let size = (Object).keys(weathers).length;
this.weathers = [];
for(let i=0;i<size;i++) {
  const adress = weathers[i].adress;
  const city = weathers[i].city;
  this.weathers.push({'adress': adress, 'city': city});
}

一种更好的方法是使用map运算符

console.log(weathers);
this.weathers = (Object).keys(weathers).map(key => {
  return {
    adress: weathers[key].adress,
    city: weathers[key].city
  }
}

TypeError：无法在SafeSubscriber._next上设置未定义的属性“地址”

1 个答案: