Question

有人可以指导吗？我收到错误，无法弄清楚为什么？ html

中的货运变量看起来有问题

app / freightList.component.html：13：8出错尝试区分＆＃39; [object Object]＆＃39;

时出错

以下是代码

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"
    }]

Answer 1

你的extractData（也可能是你的HTTP API）正在返回一个对象{} - ngFor需要一个array []来迭代。

更改服务/ API以生成数组，或转换组件中的对象。

Answer 2

当我更改WebApi时，我遇到了这个问题，我正在呼叫返回Task<IActionResult>而不是之前的IEnumerable<object>。检查响应是否未包含在对象中。我不得不将extractData方法更改为：

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

Answer 3

（对我而言）问题出在我的newState定义中。下面是正确的定义：

const newState = (state, newData) => {
    return Object.assign([], state, newData);
}

我的newState正在将数组转换为对象，因为我使用了错误的括号-错误的方式在下面。

const newState = (state, newData) => {
    return Object.assign({}, state, newData);
}

祝您好运，希望对您有所帮助，罗布

Answer 4

最好的方法是使用NgForm对象并调用其reset()函数。

示例：

Html文件

<form #exampleform='ngForm'>

</form>

ts文件

@ViewChild('exampleform') exampleform :NgForm;

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

尝试区分[对象对象]＆＃39;时出错

4 个答案: