fix(datepicker): allow DateAdapter authors to have more control over what can/can't be coerced to a date

BREAKING CHANGES:
- `fromIso8601` method on `DateAdapter` removed in favor of `coerceToDate`

Author: mmalerba

src/lib/core/datetime/date-adapter.ts

@@ -170,13 +170,6 @@ export abstract class DateAdapter<D> {
    */
   abstract toIso8601(date: D): string;
 
-  /**
-   * Creates a date from an RFC 3339 compatible string (https://tools.ietf.org/html/rfc3339).
-   * @param iso8601String The ISO date string to create a date from
-   * @returns The date created from the ISO date string.
-   */
-  abstract fromIso8601(iso8601String: string): D | null;
-
   /**
    * Checks whether the given object is considered a date instance by this DateAdapter.
    * @param obj The object to check
@@ -191,6 +184,23 @@ export abstract class DateAdapter<D> {
    */
   abstract isValid(date: D): boolean;
 
+  /**
+   * Attempts to coerce a value to a valid date object. This is different from parsing in that it
+   * should only coerce non-ambiguous, locale-independent values (e.g. a ISO 8601 string).
+   * The default implementation does not allow any coercion, it simply checks that the given value
+   * is already a valid date object or null.
+   * @param value The value to be coerced to a date object.
+   * @returns The coerced date object, either a valid date, null if the value can be coerced to a
+   *     null date (e.g. the empty string).
+   * @throws If the given value cannot be coerced to a valid date or null.
+   */
+  coerceToDate(value: any): D | null {
+    if (value == null || this.isDateInstance(value) && this.isValid(value)) {
+      return value;
+    }
+    throw Error(`Could not coerce "${value}" to a valid date object.`);
+  }
+
   /**
    * Sets the locale used for all dates.
    * @param locale The new locale.

src/lib/core/datetime/native-date-adapter.spec.ts

@@ -6,6 +6,7 @@ import {DateAdapter, MAT_DATE_LOCALE, NativeDateAdapter, NativeDateModule} from
 
 const SUPPORTS_INTL = typeof Intl != 'undefined';
 
+
 describe('NativeDateAdapter', () => {
   const platform = new Platform();
   let adapter: NativeDateAdapter;
@@ -333,14 +334,18 @@ describe('NativeDateAdapter', () => {
   });
 
   it('should create dates from valid ISO strings', () => {
-    expect(adapter.fromIso8601('1985-04-12T23:20:50.52Z')).not.toBeNull();
-    expect(adapter.fromIso8601('1996-12-19T16:39:57-08:00')).not.toBeNull();
-    expect(adapter.fromIso8601('1937-01-01T12:00:27.87+00:20')).not.toBeNull();
-    expect(adapter.fromIso8601('2017-01-01')).not.toBeNull();
-    expect(adapter.fromIso8601('2017-01-01T00:00:00')).not.toBeNull();
-    expect(adapter.fromIso8601('1990-13-31T23:59:00Z')).toBeNull();
-    expect(adapter.fromIso8601('1/1/2017')).toBeNull();
-    expect(adapter.fromIso8601('2017-01-01T')).toBeNull();
+    expect(adapter.coerceToDate('1985-04-12T23:20:50.52Z')).not.toBeNull();
+    expect(adapter.coerceToDate('1996-12-19T16:39:57-08:00')).not.toBeNull();
+    expect(adapter.coerceToDate('1937-01-01T12:00:27.87+00:20')).not.toBeNull();
+    expect(adapter.coerceToDate('2017-01-01')).not.toBeNull();
+    expect(adapter.coerceToDate('2017-01-01T00:00:00')).not.toBeNull();
+    expect(() => adapter.coerceToDate('1990-13-31T23:59:00Z')).toThrow();
+    expect(() => adapter.coerceToDate('1/1/2017')).toThrow();
+    expect(() => adapter.coerceToDate('2017-01-01T')).toThrow();
+    expect(adapter.coerceToDate('')).toBeNull();
+    expect(adapter.coerceToDate(null)).toBeNull();
+    expect(adapter.coerceToDate(new Date())).not.toBeNull();
+    expect(() => adapter.coerceToDate(new Date(NaN))).toThrow();
   });
 });
 
@@ -390,5 +395,4 @@ describe('NativeDateAdapter with LOCALE_ID override', () => {
 
     expect(adapter.getDayOfWeekNames('long')).toEqual(expectedValue);
   });
-
 });

src/lib/core/datetime/native-date-adapter.ts

@@ -7,8 +7,9 @@
  */
 
 import {Inject, Injectable, Optional} from '@angular/core';
-import {DateAdapter, MAT_DATE_LOCALE} from './date-adapter';
 import {extendObject} from '../util/object-extend';
+import {DateAdapter, MAT_DATE_LOCALE} from './date-adapter';
+
 
 // TODO(mmalerba): Remove when we no longer support safari 9.
 /** Whether the browser supports the Intl API. */
@@ -219,16 +220,26 @@ export class NativeDateAdapter extends DateAdapter<Date> {
     ].join('-');
   }
 
-  fromIso8601(iso8601String: string): Date | null {
-    // The `Date` constructor accepts formats other than ISO 8601, so we need to make sure the
-    // string is the right format first.
-    if (ISO_8601_REGEX.test(iso8601String)) {
-      let d = new Date(iso8601String);
-      if (this.isValid(d)) {
-        return d;
+  /**
+   * Returns the given value if given a valid Date or null. Coerces valid ISO 8601 strings
+   * (https://www.ietf.org/rfc/rfc3339.txt) to valid Dates and empty string to null. Throws on all
+   * other values.
+   */
+  coerceToDate(value: any): Date | null {
+    if (typeof value === 'string') {
+      if (!value) {
+        return null;
+      }
+      // The `Date` constructor accepts formats other than ISO 8601, so we need to make sure the
+      // string is the right format first.
+      if (ISO_8601_REGEX.test(value)) {
+        let date = new Date(value);
+        if (this.isValid(date)) {
+          return date;
+        }
       }
     }
-    return null;
+    return super.coerceToDate(value);
   }
 
   isDateInstance(obj: any) {

src/lib/datepicker/calendar.ts

@@ -40,7 +40,6 @@ import {
 } from '@angular/material/core';
 import {first} from 'rxjs/operator/first';
 import {Subscription} from 'rxjs/Subscription';
-import {coerceDateProperty} from './coerce-date-property';
 import {createMissingDateImplError} from './datepicker-errors';
 import {MdDatepickerIntl} from './datepicker-intl';
 
@@ -68,7 +67,7 @@ export class MdCalendar<D> implements AfterContentInit, OnDestroy {
   /** A date representing the period (month or year) to start the calendar in. */
   @Input()
   get startAt(): D | null { return this._startAt; }
-  set startAt(value: D | null) { this._startAt = coerceDateProperty(this._dateAdapter, value); }
+  set startAt(value: D | null) { this._startAt = this._dateAdapter.coerceToDate(value); }
   private _startAt: D | null;
 
   /** Whether the calendar should be started in month or year view. */
@@ -77,19 +76,19 @@ export class MdCalendar<D> implements AfterContentInit, OnDestroy {
   /** The currently selected date. */
   @Input()
   get selected(): D | null { return this._selected; }
-  set selected(value: D | null) { this._selected = coerceDateProperty(this._dateAdapter, value); }
+  set selected(value: D | null) { this._selected = this._dateAdapter.coerceToDate(value); }
   private _selected: D | null;
 
   /** The minimum selectable date. */
   @Input()
   get minDate(): D | null { return this._minDate; }
-  set minDate(value: D | null) { this._minDate = coerceDateProperty(this._dateAdapter, value); }
+  set minDate(value: D | null) { this._minDate = this._dateAdapter.coerceToDate(value); }
   private _minDate: D | null;
 
   /** The maximum selectable date. */
   @Input()
   get maxDate(): D | null { return this._maxDate; }
-  set maxDate(value: D | null) { this._maxDate = coerceDateProperty(this._dateAdapter, value); }
+  set maxDate(value: D | null) { this._maxDate = this._dateAdapter.coerceToDate(value); }
   private _maxDate: D | null;
 
   /** A function used to filter which dates are selectable. */

src/lib/datepicker/coerce-date-property.spec.ts

@@ -34,7 +34,6 @@ import {
 import {DateAdapter, MD_DATE_FORMATS, MdDateFormats} from '@angular/material/core';
 import {MdFormField} from '@angular/material/form-field';
 import {Subscription} from 'rxjs/Subscription';
-import {coerceDateProperty} from './coerce-date-property';
 import {MdDatepicker} from './datepicker';
 import {createMissingDateImplError} from './datepicker-errors';
 
@@ -123,7 +122,7 @@ export class MdDatepickerInput<D> implements AfterContentInit, ControlValueAcces
     return this._value;
   }
   set value(value: D | null) {
-    value = coerceDateProperty(this._dateAdapter, value);
+    value = this._dateAdapter.coerceToDate(value);
     this._lastValueValid = !value || this._dateAdapter.isValid(value);
     value = this._getValidDateOrNull(value);
 
@@ -141,7 +140,7 @@ export class MdDatepickerInput<D> implements AfterContentInit, ControlValueAcces
   @Input()
   get min(): D | null { return this._min; }
   set min(value: D | null) {
-    this._min = coerceDateProperty(this._dateAdapter, value);
+    this._min = this._dateAdapter.coerceToDate(value);
     this._validatorOnChange();
   }
   private _min: D | null;
@@ -150,7 +149,7 @@ export class MdDatepickerInput<D> implements AfterContentInit, ControlValueAcces
   @Input()
   get max(): D | null { return this._max; }
   set max(value: D | null) {
-    this._max = coerceDateProperty(this._dateAdapter, value);
+    this._max = this._dateAdapter.coerceToDate(value);
     this._validatorOnChange();
   }
   private _max: D | null;
@@ -198,23 +197,23 @@ export class MdDatepickerInput<D> implements AfterContentInit, ControlValueAcces
 
   /** The form control validator for the min date. */
   private _minValidator: ValidatorFn = (control: AbstractControl): ValidationErrors | null => {
-    const controlValue = coerceDateProperty(this._dateAdapter, control.value);
+    const controlValue = this._dateAdapter.coerceToDate(control.value);
     return (!this.min || !controlValue ||
         this._dateAdapter.compareDate(this.min, controlValue) <= 0) ?
         null : {'mdDatepickerMin': {'min': this.min, 'actual': controlValue}};
   }
 
   /** The form control validator for the max date. */
   private _maxValidator: ValidatorFn = (control: AbstractControl): ValidationErrors | null => {
-    const controlValue = coerceDateProperty(this._dateAdapter, control.value);
+    const controlValue = this._dateAdapter.coerceToDate(control.value);
     return (!this.max || !controlValue ||
         this._dateAdapter.compareDate(this.max, controlValue) >= 0) ?
         null : {'mdDatepickerMax': {'max': this.max, 'actual': controlValue}};
   }
 
   /** The form control validator for the date filter. */
   private _filterValidator: ValidatorFn = (control: AbstractControl): ValidationErrors | null => {
-    const controlValue = coerceDateProperty(this._dateAdapter, control.value);
+    const controlValue = this._dateAdapter.coerceToDate(control.value);
     return !this._dateFilter || !controlValue || this._dateFilter(controlValue) ?
         null : {'mdDatepickerFilter': true};
   }

src/lib/datepicker/coerce-date-property.ts

@@ -273,9 +273,8 @@ describe('MdDatepicker', () => {
       it('should throw when given wrong data type', () => {
         testComponent.date = '1/1/2017' as any;
 
-        expect(() => fixture.detectChanges()).toThrowError(
-            'Datepicker: Value must be either a date object recognized by the DateAdapter or an ' +
-            'ISO 8601 string. Instead got: 1/1/2017');
+        expect(() => fixture.detectChanges())
+            .toThrowError('Could not coerce "1/1/2017" to a valid date object.');
 
         testComponent.date = null;
       });

src/lib/datepicker/datepicker-input.ts

@@ -42,7 +42,6 @@ import {DOCUMENT} from '@angular/platform-browser';
 import {Subject} from 'rxjs/Subject';
 import {Subscription} from 'rxjs/Subscription';
 import {MdCalendar} from './calendar';
-import {coerceDateProperty} from './coerce-date-property';
 import {createMissingDateImplError} from './datepicker-errors';
 import {MdDatepickerInput} from './datepicker-input';
 
@@ -133,7 +132,7 @@ export class MdDatepicker<D> implements OnDestroy {
     // selected value is.
     return this._startAt || (this._datepickerInput ? this._datepickerInput.value : null);
   }
-  set startAt(date: D | null) { this._startAt = coerceDateProperty(this._dateAdapter, date); }
+  set startAt(date: D | null) { this._startAt = this._dateAdapter.coerceToDate(date); }
   private _startAt: D | null;
 
   /** The view that the calendar should start in. */

src/lib/datepicker/datepicker.spec.ts

@@ -22,7 +22,6 @@ import {
   MdDateFormats
 } from '@angular/material/core';
 import {MdCalendarCell} from './calendar-body';
-import {coerceDateProperty} from './coerce-date-property';
 import {createMissingDateImplError} from './datepicker-errors';
 
 
@@ -50,7 +49,7 @@ export class MdMonthView<D> implements AfterContentInit {
   get activeDate(): D { return this._activeDate; }
   set activeDate(value: D) {
     let oldActiveDate = this._activeDate;
-    this._activeDate = coerceDateProperty(this._dateAdapter, value) || this._dateAdapter.today();
+    this._activeDate = this._dateAdapter.coerceToDate(value) || this._dateAdapter.today();
     if (!this._hasSameMonthAndYear(oldActiveDate, this._activeDate)) {
       this._init();
     }
@@ -61,7 +60,7 @@ export class MdMonthView<D> implements AfterContentInit {
   @Input()
   get selected(): D | null { return this._selected; }
   set selected(value: D | null) {
-    this._selected = coerceDateProperty(this._dateAdapter, value);
+    this._selected = this._dateAdapter.coerceToDate(value);
     this._selectedDate = this._getDateInCurrentMonth(this._selected);
   }
   private _selected: D | null;

src/lib/datepicker/datepicker.ts

@@ -9,7 +9,6 @@
 export * from './datepicker-module';
 export * from './calendar';
 export * from './calendar-body';
-export * from './coerce-date-property';
 export * from './datepicker';
 export * from './datepicker-input';
 export * from './datepicker-intl';