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javascript - 如何在 Reactive Forms 中将 Select 中的当前年份设置为默认值？

问题描述

您好，我创建了一个选择，显示当前年份、过去 5 年和未来 3 年。现在我想设置它，以便当前年份始终是默认值。这应该在反应形式中完成......你知道怎么做吗？

我的代码：

// HTML
<form [formGroup]="sendYearsForm">
<select class="upload_slc" id="upload_slc" required title="" formControlName="year" 
 (change)="sendYear($event)">
   <option *ngFor="let years of sendYears" [value]="years">{{years}}</option>
</select>
 <div class="select_arrow"></div>
</form>

// TS
sendYearsForm: FormGroup;
currentDate: Date = new Date();
selectedYear: number;

// Year form
    this.sendYearsForm = this.fb.group({
      year: [null]
    });
    // Show the current year with -5 and +3
    this.selectedYear = this.currentDate.getFullYear(); // HThe current year is transferred here. How do I integrate it into the template?
    for (let i = this.currentDate.getFullYear() - 5; i <= this.currentDate.getFullYear() + 3; i++) {
      this.sendYears.push(i);
    }

标签： javascriptangulartypescriptangular-materialdropdown

解决方案

You can use patchValue to change the value of a formcontrol

yourFormGroupName.controls.yourFormControlName.patchValue(value you want to assign)

In your case

this.sendYearsForm = this.fb.group({
  year: [null]
});
// Show the current year with -5 and +3
this.selectedYear = this.currentDate.getFullYear(); // The current year is transferred here. How do I integrate it into the template?

this.sendYearsForm.controls.year.patchValue(this.selectedYear); // this will set the value of 'year' control to selectedYear(current year)

for (let i = this.currentDate.getFullYear() - 5; i <= this.currentDate.getFullYear() + 3; i++) {
  this.sendYears.push(i);
}

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