18

从rest api获取json数组对象并尝试在ngfor中显示失败，原因是

错误

例外：找不到“object”类型的不同支持对象“[object Object]”。NgFor 仅支持绑定到 Iterables，例如 Arrays。在 [HomeComponent@5:37 中的索引]

代码

import {Component} from 'angular2/core';
import {HomeService} from './home.services';
import {Index} from './index';

@Component({
    selector: 'home-app',
    providers: [HomeService],

    template: `
        <section class="left_side">
            <article>
                <div class="div_home">
                    <div class="div_homeIndxPartition">
                        <div class="div_IndxPartition" *ngFor="#indObj of indexes">
                            <table width="500px" class="idx_cons_table_det">
                                <tr>
                                    <th align="center" color="#A9F5F2"><h3>{{indObj.name}} ({{indObj.tracker}})</h3></th>
                                    <th align="center">Value</th>
                                    <th align="center">Change</th>
                                    <th align="center">%</th>
                                </tr>
                                <tr>
                                    <td align="center" colspan="1"></td>
                                    <td align="center">{{indObj.value}}</td>
                                    <td align="center">{{indObj.change}}</td>
                                    <td align="center">{{indObj.percent}}%</td>
                                </tr>
                            </table>
                            <br/>
                            <table width="500px" class="idx_cons_table">
                                <tr>
                                    <th align="center">High</th>
                                    <th align="center">Low</th>
                                    <th align="center">Open</th>
                                    <th align="center">Close</th>
                                    <th align="center">52 Week High</th>
                                    <th align="center">52 Week Low</th>                             
                                </tr>
                                <tr>
                                    <td align="center">{{indObj.high}}</td>
                                    <td align="center">{{indObj.low}}</td>
                                    <td align="center">{{indObj.open}}%</td>
                                    <td align="center">{{indObj.close}}</td>
                                    <td align="center">{{indObj.yearHigh}}</td>
                                    <td align="center">{{indObj.yearLow}}%</td>
                                </tr>
                            </table>                        
                        </div>                      
                    </div>
                </div>
            </article>
        </section>
    `

})
export class HomeComponent {
    public indexes:Array<Index>=[];
    public error;

constructor(private _service: HomeService){
    this.indexes = _service.getIndexes().subscribe(
            data => this.indexes =  JSON.parse(data),
            error => alert(" Error is : " + error),
            ()=> console.log("finished")
         );
    console.log(this.indexes);
}
}

JSON数据

[
  {
    "id": 1,
    "name": "FTSE 100",
    "ticker": "UKX",
    "value": 69875.23,
    "change": 100,
    "percent": 2.3,
    "high": 69875.23,
    "low": 69700.89,
    "yearHigh": 699999.23,
    "yearLow": 680005.23,
    "open": 69600.54,
    "close": 699000.97,
    "constituents": null,
    "runDate": "21/04/2015"
  },
  {
    "id": 2,
    "name": "FTSE 250",
    "ticker": "MCX",
    "value": 465820.85,
    "change": 100,
    "percent": 2.3,
    "high": 465880.12,
    "low": 465810.74,
    "yearHigh": 478990.34,
    "yearLow": 465320.23,
    "open": 69600.54,
    "close": 699000.97,
    "constituents": null,
    "runDate": "21/04/2015"
  },
  {
    "id": 3,
    "name": "FTSE All-Share",
    "ticker": "ASX",
    "value": 236549.23,
    "change": 100,
    "percent": 2.3,
    "high": 236949.23,
    "low": 236149,
    "yearHigh": 246949.21,
    "yearLow": 235549.29,
    "open": 236519.23,
    "close": 236649.23,
    "constituents": null,
    "runDate": "21/04/2015"
  },
  {
    "id": 4,
    "name": "Euro Stoxx 50",
    "ticker": "STOXX50E",
    "value": 123469.87,
    "change": 100,
    "percent": 2.3,
    "high": 123499.87,
    "low": 123439.87,
    "yearHigh": 123499.87,
    "yearLow": 123169.87,
    "open": 123465.87,
    "close": 123459.87,
    "constituents": null,
    "runDate": "21/04/2015"
  },
  {
    "id": 5,
    "name": "S&P 500 ",
    "ticker": "S500",
    "value": 358976.36,
    "change": 100,
    "percent": 2.3,
    "high": 358986.36,
    "low": 358946.36,
    "yearHigh": 359976.36,
    "yearLow": 357976.36,
    "open": 358970.36,
    "close": 358996.36,
    "constituents": null,
    "runDate": "21/04/2015"
  },
  {
    "id": 6,
    "name": "Dow Jones I.A.",
    "ticker": "INDU",
    "value": 456789.36,
    "change": 100,
    "percent": 2.3,
    "high": 456799.36,
    "low": 456779.36,
    "yearHigh": 456889.36,
    "yearLow": 456689.36,
    "open": 456729.36,
    "close": 456779.36,
    "constituents": null,
    "runDate": "21/04/2015"
  },
  {
    "id": 7,
    "name": "GOLD",
    "ticker": "",
    "value": 500,
    "change": 100,
    "percent": 2.3,
    "high": 700,
    "low": 300,
    "yearHigh": 1500,
    "yearLow": 350,
    "open": 450,
    "close": 470,
    "constituents": null,
    "runDate": "21/04/2015"
  },
  {
    "id": 8,
    "name": "Brent Crude",
    "ticker": "",
    "value": 112,
    "change": 100,
    "percent": 2.3,
    "high": 115,
    "low": 107,
    "yearHigh": 200,
    "yearLow": 72,
    "open": 110,
    "close": 115,
    "constituents": null,
    "runDate": "21/04/2015"
  }
]
4

5 回答 5

9

我认为您在indexes属性中设置的值不是数组而是对象。

我会看到几个原因：

  • getIndexes您从该方法收到响应而不是有效负载。在这种情况下，您可以map在此方法中使用运算符：

    getIndexes() {
  return this.http.get(...).map(res => res.json());
}

  • 接收到的有效载荷不对应于数组，而是对应于它的一些属性。在这种情况下，您需要将此属性设置为indexes属性。

如果要遍历对象的属性，则需要实现一个自定义过滤器，如下所示：

@Pipe({name: 'keyValues'})
export class KeysPipe implements PipeTransform {
  transform(value, args:string[]) : any {
    let keys = [];
    for (let key in value) {
      keys.push({key: key, value: value[key]);
    }
    return keys;
  }
}

并像这样使用它：

<div class="div_IndxPartition" *ngFor="#indObj of indexes | keyValues">
  (...)
</div>

看到这个问题：

于 2016-04-25T11:29:23.950 回答
1

你应该试试这个：

在 html 中：

<div  *ngFor="let subsciption of subscriptions;">
                     <div class="col-md-6">
                        <h5 class="widget-title">{{subsciption.name}}</h5>
                    </div>
</div>

在 .ts 文件中：

    export class SubscriptionComponent implements OnInit {
        private subscriptions: any =[]; 
        // private subscriptions: any ={};    // here dont use {}
    .
    .
    .
    .
    .

        getAllSubscriptions(queryString) {
            this._http.get(`${environment.base_url}/subscriptions` + queryString)
                .subscribe((response: Response) => {
                    this.subscriptions = response.json();
                },

                (error: Response) => {
                    console.log("Login error");
                });
        }
        this.getAllSubscriptions(query);

    }
于 2017-05-04T13:33:25.800 回答
0

我有同样的问题，我的解决方案是没有管道。我没有在返回观察者的模板中使用变量，创建中间变量并将结果分配给它。例如，我们将流保存到，this.sub但结果将保存到this.indexes成功回调，并将在 html 模板中使用此变量。

@Component({
  template: `
<ul>
  <li *ngFor="let index of indexs">
    {{ index }}
  </li>
</ul>
`
})
export class HomeComponent {
  privat sub;
  public indexes:Array<Index>=[];
  public error;

  constructor(private _service: HomeService) {
    this.sub = this._service.getIndexes().subscribe(
        data => this.indexes =  JSON.parse(data),
        error => alert(" Error is : " + error),
        () => console.log("finished")
     );

  }
}
于 2016-10-16T20:52:37.043 回答
0

在使用 Observables 时，您不想使用管道。这个错误非常普遍，最好的方法是抛出一个 console.log() 并查看你哪里出错了，因为它可能有很多东西。

我的问题是我的数组在对象内部，我试图遍历对象。其他问题可能包括映射或 ngFor。我的控制台输出看起来像这样：

this.indexes = _service.getIndexes()
         .subscribe(
            data => {
                this.indexes = JSON.parse(data);
                console.log(indexes);
            },
            error => alert(" Error is : " + error),
                ()=> console.log("finished")
         );
    console.log(this.indexes);

所以我需要的修复是这样的：

this.indexes = _service.getIndexes()
             .subscribe(
                data => {
                    this.myNewObject = JSON.parse(data);
                    this.indexes = this.myNewObject.indexes;
                },
                error => alert(" Error is : " + error),
                    ()=> console.log("finished")
             );
        console.log(this.indexes);

这是因为数组嵌套在 Object 中，所以我只是创建了一个新对象并通过获取它的属性来访问该数组。

于 2017-06-24T21:36:49.507 回答
0

我看到了你的答案，解决的简单方法是将 *ngFor 中的对象类型设置为这样的数组：

public indexes:Array<TYPE_OF_YOUR_DATA>=[];
于 2019-06-19T16:43:43.207 回答