Angular Material 禁用月份

Question

我将我的 Angular 项目用于 Angular material 年月选择器。任何人都知道如何只显示选择的年份。

stackblitz here

.html

<mat-form-field appearance="fill">
  <mat-label>Month and Year</mat-label>
  <input matInput [matDatepicker]="dp" [formControl]="date">
  <mat-datepicker-toggle matSuffix [for]="dp"></mat-datepicker-toggle>
  <mat-datepicker #dp
                  startView="multi-year"
                  (yearSelected)="chosenYearHandler($event)"
                  (monthSelected)="chosenMonthHandler($event, dp)"
                  panelClass="example-month-picker">
  </mat-datepicker>
</mat-form-field>

.ts

import {Component} from '@angular/core';
import {FormControl} from '@angular/forms';
import {MomentDateAdapter, MAT_MOMENT_DATE_ADAPTER_OPTIONS} from '@angular/material-moment-adapter';
import {DateAdapter, MAT_DATE_FORMATS, MAT_DATE_LOCALE} from '@angular/material/core';
import {MatDatepicker} from '@angular/material/datepicker';

// Depending on whether rollup is used, moment needs to be imported differently.
// Since Moment.js doesn't have a default export, we normally need to import using the `* as`
// syntax. However, rollup creates a synthetic default module and we thus need to import it using
// the `default as` syntax.
import * as _moment from 'moment';
// tslint:disable-next-line:no-duplicate-imports
import {default as _rollupMoment, Moment} from 'moment';

const moment = _rollupMoment || _moment;

// See the Moment.js docs for the meaning of these formats:
// https://momentjs.com/docs/#/displaying/format/
export const MY_FORMATS = {
  parse: {
    dateInput: 'MM/YYYY',
  },
  display: {
    dateInput: 'MM/YYYY',
    monthYearLabel: 'MMM YYYY',
    dateA11yLabel: 'LL',
    monthYearA11yLabel: 'MMMM YYYY',
  },
};

/** @title Datepicker emulating a Year and month picker */
@Component({
  selector: 'datepicker-views-selection-example',
  templateUrl: 'datepicker-views-selection-example.html',
  styleUrls: ['datepicker-views-selection-example.css'],
  providers: [
    // `MomentDateAdapter` can be automatically provided by importing `MomentDateModule` in your
    // application's root module. We provide it at the component level here, due to limitations of
    // our example generation script.
    {
      provide: DateAdapter,
      useClass: MomentDateAdapter,
      deps: [MAT_DATE_LOCALE, MAT_MOMENT_DATE_ADAPTER_OPTIONS]
    },

    {provide: MAT_DATE_FORMATS, useValue: MY_FORMATS},
  ],
})
export class DatepickerViewsSelectionExample {
  date = new FormControl(moment());

  chosenYearHandler(normalizedYear: Moment) {
    const ctrlValue = this.date.value;
    ctrlValue.year(normalizedYear.year());
    this.date.setValue(ctrlValue);
  }

  chosenMonthHandler(normalizedMonth: Moment, datepicker: MatDatepicker<Moment>) {
    const ctrlValue = this.date.value;
    ctrlValue.month(normalizedMonth.month());
    this.date.setValue(ctrlValue);
    datepicker.close();
  }
}

Answer 1

概念（简而言之）

1. 将 MY_FORMATS 日期输入设置为 YYYY 以仅显示年份。
2. Glue：为 NG_VALUE_ACCESSOR 添加供应商和多供应商以扩展现有供应商。 （参考参考文献2）
3. Machinery：对组件实施 ControlValueAccessor 以将自定义表单控件值与 Angular Reactive Forms 集成。 （参考参考文献2 & 3）

---

解决方案

datepicker-views-selection-example.html

<mat-form-field appearance="fill">
  <mat-label>Month and Year</mat-label>
  <input matInput
        [matDatepicker]="dp"
        [formControl]="date"
         (click)="_openDatepickerOnClick(dp)"
         (keydown.arrowdown)="_openDatepickerOnClick(dp)"
         (keydown.enter)="_openDatepickerOnClick(dp)">
  <mat-datepicker-toggle matSuffix [for]="dp"></mat-datepicker-toggle>
  <mat-datepicker #dp 
                  startView="multi-year" 
                  (yearSelected)="chosenYearHandler($event, dp)"
                  (monthSelected)="chosenMonthHandler($event, dp)"
                  panelClass="example-month-picker">
  </mat-datepicker>
</mat-form-field>

datepicker-views-selection-example.ts

import { Component, forwardRef, Input, ViewChild } from '@angular/core';
import {
  ControlValueAccessor,
  FormControl,
  NG_VALUE_ACCESSOR
} from '@angular/forms';
import {
  MomentDateAdapter,
  MAT_MOMENT_DATE_ADAPTER_OPTIONS
} from '@angular/material-moment-adapter';
import {
  DateAdapter,
  MAT_DATE_FORMATS,
  MAT_DATE_LOCALE
} from '@angular/material/core';
import { MatDatepicker } from '@angular/material/datepicker';

// Depending on whether rollup is used, moment needs to be imported differently.
// Since Moment.js doesn't have a default export, we normally need to import using the `* as`
// syntax. However, rollup creates a synthetic default module and we thus need to import it using
// the `default as` syntax.
import * as _moment from 'moment';
// tslint:disable-next-line:no-duplicate-imports
import { default as _rollupMoment, Moment } from 'moment';

const moment = _rollupMoment || _moment;

// See the Moment.js docs for the meaning of these formats:
// https://momentjs.com/docs/#/displaying/format/
export const MY_FORMATS = {
  parse: {
    dateInput: 'YYYY'
  },
  display: {
    dateInput: 'YYYY',
    monthYearLabel: 'MMM YYYY',
    dateA11yLabel: 'LL',
    monthYearA11yLabel: 'MMMM YYYY'
  }
};

/** @title Datepicker emulating a Year and month picker */
@Component({
  selector: 'datepicker-views-selection-example',
  templateUrl: 'datepicker-views-selection-example.html',
  styleUrls: ['datepicker-views-selection-example.css'],
  providers: [
    // `MomentDateAdapter` can be automatically provided by importing `MomentDateModule` in your
    // application's root module. We provide it at the component level here, due to limitations of
    // our example generation script.
    {
      provide: DateAdapter,
      useClass: MomentDateAdapter,
      deps: [MAT_DATE_LOCALE, MAT_MOMENT_DATE_ADAPTER_OPTIONS]
    },
    { provide: MAT_DATE_FORMATS, useValue: MY_FORMATS },
    {
      provide: NG_VALUE_ACCESSOR,
      useExisting: forwardRef(() => DatepickerViewsSelectionExample),
      multi: true
    }
  ]
})
export class DatepickerViewsSelectionExample implements ControlValueAccessor {
  @ViewChild('dp') dp: MatDatepicker<Moment>;

  date = new FormControl(moment());

  _max: Moment | undefined;
  @Input()
  get max(): Moment | undefined {
    return this._max ? this._max : undefined;
  }
  set max(max: Moment | undefined) {
    if (max) {
      const momentDate: Moment =
        typeof max === 'number' ? moment([max, 0, 1]) : moment(max);
      this._max = momentDate.isValid() ? momentDate : undefined;
    }
  }

  _min: Moment | undefined;
  @Input()
  get min(): Moment | undefined {
    return this._min ? this._min : undefined;
  }
  set min(min: Moment | undefined) {
    if (min) {
      const momentDate =
        typeof min === 'number' ? moment([min, 0, 1]) : moment(min);
      this._min = momentDate.isValid() ? momentDate : undefined;
    }
  }

  // Function to call when the date changes.
  onChange = (year: Date) => {};

  // Function to call when the input is touched (when a star is clicked).
  onTouched = () => {};

  writeValue(date: Date): void {
    if (date && this._isYearEnabled(date.getFullYear())) {
      const momentDate = moment(date);
      if (momentDate.isValid()) {
        momentDate.set({ date: 1 });
        this.date.setValue(moment(date), { emitEvent: false });
      }
    }
  }

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

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

  // Allows Angular to disable the input.
  setDisabledState(isDisabled: boolean): void {
    isDisabled ? (this.dp.disabled = true) : (this.dp.disabled = false);

    isDisabled ? this.date.disable() : this.date.enable();
  }

  chosenYearHandler(normalizedYear: Moment, datepicker: MatDatepicker<Moment>) {
    datepicker.close();

    if (!this._isYearEnabled(normalizedYear.year())) {
      return;
    }

    normalizedYear.set({ date: 1 });

    this.date.setValue(normalizedYear, { emitEvent: false });
    this.onTouched();
  }

  chosenMonthHandler(
    normalizedMonth: Moment,
    datepicker: MatDatepicker<Moment>
  ) {
    datepicker.close();

    this.date.setValue(normalizedMonth.month());
    this.onTouched();
  }

  _openDatepickerOnClick(datepicker: MatDatepicker<Moment>) {
    if (!datepicker.opened) {
      datepicker.open();
    }
  }

  // disable if the year is greater than maxDate lower than minDate
  private _isYearEnabled(year: number) {
    if (
      year === undefined ||
      year === null ||
      (this._max && year > this._max.year()) ||
      (this._min && year < this._min.year())
    ) {
      return false;
    }

    return true;
  }
}

Sample Solution on StackBlitz

---

参考资料

2. Connect your custom control to ngModel with Control Value Accessor.
3. ControlValueAccessor