尝试差异'[对象对象]'错误

任何人都可以引导？我收到错误，无法弄清楚为什么？看起来像HTML有毛病货运可变尝试差异'[对象对象]'错误

错误在app/freightList.component.html：13：8 错误尝试的差异 '的翻译：'

下面是代码

freight.service.ts 
======================= 

    getFreight(): Promise<Freight[]> { 
     return this.http.get(this.freightUrl) 
        .toPromise() 
        .then(this.extractData) 
        .catch(this.handleError); 
    } 

    private extractData(res: Response) { 
     let body = res.json(); 
     return body || { }; 
    } 

freightList.component.ts 
======================== 
    getFreight() { 
     this.freightService 
      .getFreight() 
      .then(freight => this.freight = freight) 
      .catch(error => this.error = error); // TODO: Display error message 
    } 

freightList.component.html 
============================ 

     <tr *ngFor="let frght of freight"> 
     <td>{{frght.grp}} - {{frght.grpname}}</td> 
     <td>{{frght.subgrp}} - {{frght.subgrpname}}</td> 
     <td>{{frght.prodno}} - {{frght.prodname}}</td> 
     <td>{{frght.percent}}</td> 
     <td>{{frght.effective_date}}</td> 
     <td><button (click)="deleteFreight(frght, $event)" class="btn btn-danger btn-sm"><span class="glyphicon glyphicon-remove"></span> Remove</button></td> 
     <td><button (click)="editFreight(frght)" class="btn btn-warning btn-sm"><span class="glyphicon glyphicon-edit"></span> Edit</button></td> 
     </tr> 

Response body 
================== 

    [{ 
     "effective_date": "01/01/2016", 
     "grp": "01", 
     "grpname": "STOPS/FLEX HOSES/COVER PLATES", 
     "id": "1", 
     "percent": "10", 
     "prodname": "DWV PVC PIPE 100MM X 6MTR SN6 SWJ", 
     "prodno": "1400200", 
     "subgrp": "02", 
     "subgrpname": "DWV PIPE - UP TO 150MM" 
    }, { 
     "effective_date": "01/02/2016", 
     "grp": "01", 
     "grpname": "STOPS/FLEX HOSES/COVER PLATES", 
     "id": "2", 
     "percent": "11", 
     "prodname": "PVC PIPE 100MM X 6MTR SWJ SN10", 
     "prodno": "1400201", 
     "subgrp": "03", 
     "subgrpname": "DIMPLEX BATHROOM ACCESSORIES" 
    }]

来源

2016-07-06 sourabh kumar

您的extractData（也可能是您的HTTP API）正在返回一个对象{} - ngFor需要一个数组[]来迭代。

更改您的服务/ API以生成数组或转换组件中的对象。

来源

2016-08-24 23:25:09 retrospectacus

我遇到了这个问题时，我改变了WebApi我打电话来返回Task<IActionResult>，而不是以前的IEnumerable<object>。检查响应是否未包含在对象中。我不得不改变我的ExtractData由方法：

private extractData(res: Response) { 
    let body = res.json(); 
    return body.result || body || { }; 
}

来源

2018-02-02 11:33:36

最好的办法是采取NgForm对象，并调用其reset()功能。

实施例：

HTML文件

<form #exampleform='ngForm'> 

</form>

TS文件

@ViewChild('exampleform') exampleform :NgForm; 

this.exampleform.reset(); // resets the form

来源

2018-03-04 01:43:43

尝试差异'[对象对象]'错误

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