Question

我有一个ngFor和发票总额是计算价格和小时数但我仍然想要所有总数的总数

<tr *ngFor="let invoice of invoiceItem.rows">
    <td>{{ invoice.rowName }}</td>
    <td>{{ invoice.hours}}</td>
    <td>{{ invoice.price }}</td>
    <td>{{ invoice.comments }}</td>
    <td>{{ invoice.total}} </td>

</tr>
<tr>
    <td></td>
    <td></td>
    <td></td>
    <td>total ex 18%</td>
    <td>{{ totals }}</td>
</tr>

并且在typescript文件中我有应该计算总数的构造函数。几个小时后，我想是时候问:(

export class DemoTestComponent {
    public invoiceItem: ItemInvoice;
    public invoiceItem2: ItemInvoice;

    public invoices: InvoiceData;
    public invoiceRows: InvoiceDetailsRows[];
    public totals: number;
    //public theTex: number;
    //public totalsAfterTax: number;
    constructor(http: Http) {
        http.get('/api/Invoice/test/1').subscribe(result => {
            this.invoiceItem = result.json();
            this.invoiceItem.rows.forEach((item) => {
                item.total = calculate(item);
            })
            var tempnumber;
            this.invoiceItem.rows.forEach((item) => {
                tempnumber += item.total;
            })
            this.totals = tempnumber;
            //this.theTex = this.totals * 0.18;
            //this.totalsAfterTax = this.totals + this.theTex;

        });

    }
}

Answer 1

可能是你遇到的问题是因为你在构造函数中调用它。你应该在ngoninit中调用它。我们所有的http请求都应该在生命周期钩子中而不是在构造函数中。

  export class DemoTestComponent {
            public invoiceItem: ItemInvoice;
            public invoiceItem2: ItemInvoice;

            public invoices: InvoiceData;
            public invoiceRows: InvoiceDetailsRows[];
            public totals: number;
            //public theTex: number;
            //public totalsAfterTax: number;
            constructor(http: Http) { }
            ngOnInit() { 
              http.get('/api/Invoice/test/1')
                    .map(result => result.json())
                    .subscribe(result => {
                    this.invoiceItem = result;
                    this.invoiceItem.rows.forEach((item) => {
                        item.total = calculate(item);
                    })
                    var tempnumber=0;
                    this.invoiceItem.rows.forEach((item) => {
                        tempnumber += item.total;
                    })
                    this.totals = tempnumber;
                    //this.theTex = this.totals * 0.18;
                    //this.totalsAfterTax = this.totals + this.theTex;
                });
             }
          }

你收到任何错误？如果仍然出现任何错误，则显示您的Json数据。我会编辑我的答案。

Answer 2

您尚未初始化var tempnumber;，因此，它是undefined，并且当您尝试在循环中对其进行求和时将返回NaN。

改变这一位：

var tempnumber;

到

var tempnumber = 0;

尝试在块范围变量中使用let而不是var。

或使用reduce

let tempnumber = 0;
this.invoiceItem.rows.reduce((total, current) => tempnumber = total + current, tempnumber);

this.totals = tempnumber;

如何汇总表中的所有字段

2 个答案: