feat(datepicker): allow custom classes to be applied to individual dates (#13971)

Adds the `dateClass` function which allows consumers to apply custom CSS classes to specific dates. This is useful for highlighting specific dates like a holiday.

Fixes #13943.

Author: crisbeto

src/lib/datepicker/calendar-body.html

@@ -30,6 +30,7 @@
   <td *ngFor="let item of row; let colIndex = index"
       role="gridcell"
       class="mat-calendar-body-cell"
+      [ngClass]="item.cssClasses"
       [tabindex]="_isActiveCell(rowIndex, colIndex) ? 0 : -1"
       [class.mat-calendar-body-disabled]="!item.enabled"
       [class.mat-calendar-body-active]="_isActiveCell(rowIndex, colIndex)"

src/lib/datepicker/calendar-body.spec.ts

@@ -1,6 +1,6 @@
 import {async, ComponentFixture, TestBed} from '@angular/core/testing';
 import {Component} from '@angular/core';
-import {MatCalendarBody, MatCalendarCell} from './calendar-body';
+import {MatCalendarBody, MatCalendarCell, MatCalendarCellCssClasses} from './calendar-body';
 import {By} from '@angular/platform-browser';
 
 
@@ -98,6 +98,14 @@ describe('MatCalendarBody', () => {
       expect((cellEls[10] as HTMLElement).innerText.trim()).toBe('11');
       expect(cellEls[10].classList).toContain('mat-calendar-body-active');
     });
+
+    it('should set a class on even dates', () => {
+      expect((cellEls[0] as HTMLElement).innerText.trim()).toBe('1');
+      expect((cellEls[1] as HTMLElement).innerText.trim()).toBe('2');
+      expect(cellEls[0].classList).not.toContain('even');
+      expect(cellEls[1].classList).toContain('even');
+    });
+
   });
 
 });
@@ -117,7 +125,9 @@ describe('MatCalendarBody', () => {
 })
 class StandardCalendarBody {
   label = 'Jan 2017';
-  rows = [[1, 2, 3, 4, 5, 6, 7], [8, 9, 10, 11, 12, 13, 14]].map(r => r.map(createCell));
+  rows = [[1, 2, 3, 4, 5, 6, 7], [8, 9, 10, 11, 12, 13, 14]].map(row => {
+    return row.map(cell => createCell(cell, cell % 2 === 0 ? 'even' : undefined));
+  });
   todayValue = 3;
   selectedValue = 4;
   labelMinRequiredCells = 3;
@@ -128,6 +138,6 @@ class StandardCalendarBody {
   }
 }
 
-function createCell(value: number) {
-  return new MatCalendarCell(value, `${value}`, `${value}-label`, true);
+function createCell(value: number, cellClasses?: MatCalendarCellCssClasses) {
+  return new MatCalendarCell(value, `${value}`, `${value}-label`, true, cellClasses);
 }

src/lib/datepicker/calendar-body.ts

@@ -18,6 +18,11 @@ import {
 } from '@angular/core';
 import {take} from 'rxjs/operators';
 
+/**
+ * Extra CSS classes that can be associated with a calendar cell.
+ */
+export type MatCalendarCellCssClasses = string | string[] | Set<string> | {[key: string]: any};
+
 /**
  * An internal class that represents the data corresponding to a single calendar cell.
  * @docs-private
@@ -26,7 +31,8 @@ export class MatCalendarCell {
   constructor(public value: number,
               public displayValue: string,
               public ariaLabel: string,
-              public enabled: boolean) {}
+              public enabled: boolean,
+              public cssClasses?: MatCalendarCellCssClasses) {}
 }
 
 

src/lib/datepicker/calendar.html

@@ -9,6 +9,7 @@
       [dateFilter]="dateFilter"
       [maxDate]="maxDate"
       [minDate]="minDate"
+      [dateClass]="dateClass"
       (selectedChange)="_dateSelected($event)"
       (_userSelection)="_userSelected()">
   </mat-month-view>

src/lib/datepicker/calendar.ts

@@ -32,6 +32,7 @@ import {MatDatepickerIntl} from './datepicker-intl';
 import {MatMonthView} from './month-view';
 import {MatMultiYearView, yearsPerPage} from './multi-year-view';
 import {MatYearView} from './year-view';
+import {MatCalendarCellCssClasses} from './calendar-body';
 
 /**
  * Possible views for the calendar.
@@ -220,9 +221,12 @@ export class MatCalendar<D> implements AfterContentInit, AfterViewChecked, OnDes
   }
   private _maxDate: D | null;
 
-  /** A function used to filter which dates are selectable. */
+  /** Function used to filter which dates are selectable. */
   @Input() dateFilter: (date: D) => boolean;
 
+  /** Function that can be used to add custom CSS classes to dates. */
+  @Input() dateClass: (date: D) => MatCalendarCellCssClasses;
+
   /** Emits when the currently selected date changes. */
   @Output() readonly selectedChange: EventEmitter<D> = new EventEmitter<D>();
 

src/lib/datepicker/datepicker-content.html

@@ -8,6 +8,7 @@
     [dateFilter]="datepicker._dateFilter"
     [headerComponent]="datepicker.calendarHeaderComponent"
     [selected]="datepicker._selected"
+    [dateClass]="datepicker.dateClass"
     [@fadeInCalendar]="'enter'"
     (selectedChange)="datepicker.select($event)"
     (yearSelected)="datepicker._selectYear($event)"

src/lib/datepicker/datepicker.md

@@ -328,6 +328,14 @@ application root module.
 export class MyApp {}
 ```
 
+#### Highlighting specific dates
+If you want to apply one or more CSS classes to some dates in the calendar (e.g. to highlight a
+holiday), you can do so with the `dateClass` input. It accepts a function which will be called
+with each of the dates in the calendar and will apply any classes that are returned. The return
+value can be anything that is accepted by `ngClass`.
+
+<!-- example(datepicker-date-class) -->
+
 ### Accessibility
 
 The `MatDatepickerInput` and `MatDatepickerToggle` directives add the `aria-haspopup` attribute to

src/lib/datepicker/datepicker.ts

@@ -50,6 +50,7 @@ import {MatCalendar} from './calendar';
 import {matDatepickerAnimations} from './datepicker-animations';
 import {createMissingDateImplError} from './datepicker-errors';
 import {MatDatepickerInput} from './datepicker-input';
+import {MatCalendarCellCssClasses} from './calendar-body';
 
 /** Used to generate a unique ID for each datepicker instance. */
 let datepickerUid = 0;
@@ -212,6 +213,9 @@ export class MatDatepicker<D> implements OnDestroy, CanColor {
   /** Classes to be passed to the date picker panel. Supports the same syntax as `ngClass`. */
   @Input() panelClass: string | string[];
 
+  /** Function that can be used to add custom CSS classes to dates. */
+  @Input() dateClass: (date: D) => MatCalendarCellCssClasses;
+
   /** Emits when the datepicker has been opened. */
   @Output('opened') openedStream: EventEmitter<void> = new EventEmitter<void>();
 

src/lib/datepicker/month-view.spec.ts

@@ -35,6 +35,7 @@ describe('MatMonthView', () => {
         // Test components.
         StandardMonthView,
         MonthViewWithDateFilter,
+        MonthViewWithDateClass,
       ],
       providers: [
         {provide: Directionality, useFactory: () => dir = {value: 'ltr'}}
@@ -291,6 +292,26 @@ describe('MatMonthView', () => {
       expect(cells[1].classList).not.toContain('mat-calendar-body-disabled');
     });
   });
+
+  describe('month view with custom date classes', () => {
+    let fixture: ComponentFixture<MonthViewWithDateClass>;
+    let monthViewNativeElement: Element;
+
+    beforeEach(() => {
+      fixture = TestBed.createComponent(MonthViewWithDateClass);
+      fixture.detectChanges();
+
+      let monthViewDebugElement = fixture.debugElement.query(By.directive(MatMonthView));
+      monthViewNativeElement = monthViewDebugElement.nativeElement;
+    });
+
+    it('should be able to add a custom class to some dates', () => {
+      let cells = monthViewNativeElement.querySelectorAll('.mat-calendar-body-cell');
+      expect(cells[0].classList).not.toContain('even');
+      expect(cells[1].classList).toContain('even');
+    });
+  });
+
 });
 
 
@@ -312,3 +333,13 @@ class MonthViewWithDateFilter {
     return date.getDate() % 2 == 0;
   }
 }
+
+@Component({
+  template: `<mat-month-view [activeDate]="activeDate" [dateClass]="dateClass"></mat-month-view>`
+})
+class MonthViewWithDateClass {
+  activeDate = new Date(2017, JAN, 1);
+  dateClass(date: Date) {
+    return date.getDate() % 2 == 0 ? 'even' : undefined;
+  }
+}

src/lib/datepicker/month-view.ts

@@ -33,7 +33,7 @@ import {
 } from '@angular/core';
 import {DateAdapter, MAT_DATE_FORMATS, MatDateFormats} from '@angular/material/core';
 import {Directionality} from '@angular/cdk/bidi';
-import {MatCalendarBody, MatCalendarCell} from './calendar-body';
+import {MatCalendarBody, MatCalendarCell, MatCalendarCellCssClasses} from './calendar-body';
 import {createMissingDateImplError} from './datepicker-errors';
 
 
@@ -94,9 +94,12 @@ export class MatMonthView<D> implements AfterContentInit {
   }
   private _maxDate: D | null;
 
-  /** A function used to filter which dates are selectable. */
+  /** Function used to filter which dates are selectable. */
   @Input() dateFilter: (date: D) => boolean;
 
+  /** Function that can be used to add custom CSS classes to dates. */
+  @Input() dateClass: (date: D) => MatCalendarCellCssClasses;
+
   /** Emits when a new date is selected. */
   @Output() readonly selectedChange: EventEmitter<D | null> = new EventEmitter<D | null>();
 
@@ -273,8 +276,10 @@ export class MatMonthView<D> implements AfterContentInit {
             this._dateAdapter.getMonth(this.activeDate), i + 1);
       const enabled = this._shouldEnableDate(date);
       const ariaLabel = this._dateAdapter.format(date, this._dateFormats.display.dateA11yLabel);
+      const cellClasses = this.dateClass ? this.dateClass(date) : undefined;
+
       this._weeks[this._weeks.length - 1]
-          .push(new MatCalendarCell(i + 1, dateNames[i], ariaLabel, enabled));
+          .push(new MatCalendarCell(i + 1, dateNames[i], ariaLabel, enabled, cellClasses));
     }
   }