angular2 和 ngIf - 测试是否大于或小于

Question

我该如何进行这项工作？如果值为 9 或更小，则显示 "Month"，否则显示 "Months"。这是我的代码：

<select id="analysis_horizon" class="custom-select form-control" [(ngModel)]="basic_setup.analysis_horizon" formControlName="analysis_horizon" describedby="basic-addon_analysis_horizon">
    <option disabled>Select Analysis Horizon</option>
    <option *ngIf="'i<=9'" *ngFor="let i of analysis_horizon_array">{{i}} Month</option>
    <option *ngIf="'i>9'" *ngFor="let i of analysis_horizon_array">{{i}} Months</option>
</select>

这是我得到的错误：

Can't have multiple template bindings on one element. Use only one attribute named 'template' or prefixed with * ("isabled>Select Analysis Horizon ]*ngFor="let i of analysis_horizon_array">{{i}} Month {{i}} Month 9'" [ERROR ->]*ngFor="let i of analysis_horizon_array">{{i}} Months ; Task: Promise.then ; Value: Error: Template parse errors:(…) Error: Template parse errors: Can't have multiple template bindings on one element. Use only one attribute named 'template' or prefixed with * ("isabled>Select Analysis Horizon ]*ngFor="let i of analysis_horizon_array">{{i}} Month {{i}} Month 9'" [ERROR ->]*ngFor="let i of analysis_horizon_array">{{i}} Months

Answer 1

您不能在一个元素上使用多个模板绑定，在本例中为 *ngIf 和 *ngFor。你可以用插值和三元运算符实现你想要的，你不需要使用 *ngIf 指令：

<select id="analysis_horizon" class="custom-select form-control" [(ngModel)]="basic_setup.analysis_horizon" formControlName="analysis_horizon" describedby="basic-addon_analysis_horizon">
    <option disabled>Select Analysis Horizon</option>
    <option *ngFor="let i of analysis_horizon_array">
        {{i}} {{ i <= 9 ? "Month" : "Months" }}
    </option>
</select>

angular2 和 ngIf - 测试是否大于或小于

angular2 and ngIf - test if greater or less than

angular-template

angular-directive

angular