以角度形式删除重复的属性(ngModel，值) [英] Remove duplicate attribute(ngModel, value) in angular forms

问题描述

我制作了一个 DatePickerDirective，它按要求工作正常.但是为了同步该指令所在的特定输入字段的值，我必须同时使用 value 和 ngModel 属性.我希望只使用 ngModel 如何优雅地实现这一点.

I have made a DatePickerDirective which is working fine as required. But in order to sync the value of the particular input field on which this directive sits, I have to use value and ngModel attribute both. I wish to use only ngModel how can this be achieved gracefully.

表单元素

 <input appDatePicker type="text" required name="title" value="{{holiday.off_date}}" [(ngModel)]="holiday.off_date" class="form-control"
                       placeholder="01/01/2018">

组件文件

export class HolidayCreateComponent implements OnInit, OnDestroy {

  holiday = new HolidayModel('', '');

}

模型文件

export class HolidayModel {

  constructor(public occasion: string, public off_date: string) {
  }

}

指令文件

import {Directive, ElementRef, forwardRef, OnInit} from '@angular/core';
import {ControlValueAccessor, NG_VALUE_ACCESSOR} from '@angular/forms';

declare const $: any;

@Directive({
  selector: '[appDatePicker]',
  providers: [{
    provide: NG_VALUE_ACCESSOR, useExisting:
      forwardRef(() => DatePickerDirective),
    multi: true
  }]
})
export class DatePickerDirective implements OnInit, ControlValueAccessor {

  value: string;

  constructor(private el: ElementRef) {

  }


  ngOnInit() {
    $(this.el.nativeElement).datepicker({
      autoclose: true,
      todayHighlight: true,
      format: 'dd/mm/yyyy'
    }).on('change', e => this._onChange(e.target.value));
  }


  private _onChange(_) {
  }

  private _onTouched(_) {
  }

  registerOnChange(fn: any): void {
    this._onChange = fn;
  }

  registerOnTouched(fn: any): void {
    this._onTouched = fn;
  }

  setDisabledState(isDisabled: boolean): void {
  }

  writeValue(val: string): void {
    this.value = val;
  }


}

问题是每当我尝试从组件操作日期字段的值时，我都需要同时使用 value 和 ngmodel.我觉得这是不对的可以改进.有什么我忘记的吗.

The problem is whenever i try to manipulate value of date field from component i need use both value and ngmodel. I think this is not right can be improved. Is there anything which i forgot.

注意:只有在使用指令时才需要值和 ngModel.如果输入没有指令，那么 ngModel 工作得很好.我希望具有指令的元素具有相同的行为.

NOTE: the value and ngModel is required only where directive is used. If the input has no directive then ngModel works just perfect. I want the same behavior for the element with directive.

推荐答案

value 仅表示 initial，日期选择器的默认值.ngModel 是双向绑定对象，它包含用户选择日期后的数据.你的代码很好.

value simply means the initial, default value of the datepicker. ngModel is the two-way bound object that has your data afther the user pick's the date. Your code is fine as it is.

这篇关于以角度形式删除重复的属性(ngModel，值)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！