feat(dialog): allow for closing on navigation to be disabled

Allows consumers to opt out of the functionality that closes all of the open dialogs when going backwards/forwards in history.

Fixes angular#8983.

src/lib/dialog/dialog-config.ts

@@ -98,5 +98,8 @@ export class MatDialogConfig<D = any> {
   /** Scroll strategy to be used for the dialog. */
   scrollStrategy?: ScrollStrategy;
 
+  /** Whether the dialog should close when the user goes backwards/forwards in history. */
+  closeOnNavigation?: boolean = true;
+
   // TODO(jelbourn): add configuration for lifecycle hooks, ARIA labelling.
 }

src/lib/dialog/dialog-ref.ts

@@ -8,11 +8,13 @@
 
 import {OverlayRef, GlobalPositionStrategy} from '@angular/cdk/overlay';
 import {ESCAPE} from '@angular/cdk/keycodes';
+import {Location} from '@angular/common';
 import {filter} from 'rxjs/operators/filter';
 import {take} from 'rxjs/operators/take';
 import {DialogPosition} from './dialog-config';
 import {Observable} from 'rxjs/Observable';
 import {Subject} from 'rxjs/Subject';
+import {Subscription, ISubscription} from 'rxjs/Subscription';
 import {MatDialogContainer} from './dialog-container';
 
 
@@ -43,9 +45,13 @@ export class MatDialogRef<T, R = any> {
   /** Result to be passed to afterClosed. */
   private _result: R | undefined;
 
+  /** Subscription to changes in the user's location. */
+  private _locationChanges: ISubscription = Subscription.EMPTY;
+
   constructor(
     private _overlayRef: OverlayRef,
     private _containerInstance: MatDialogContainer,
+    location?: Location,
     readonly id: string = `mat-dialog-${uniqueId++}`) {
 
     // Emit when opening animation completes
@@ -65,6 +71,7 @@ export class MatDialogRef<T, R = any> {
     )
     .subscribe(() => {
       this._overlayRef.dispose();
+      this._locationChanges.unsubscribe();
       this._afterClosed.next(this._result);
       this._afterClosed.complete();
       this.componentInstance = null!;
@@ -73,6 +80,17 @@ export class MatDialogRef<T, R = any> {
     _overlayRef.keydownEvents()
       .pipe(filter(event => event.keyCode === ESCAPE && !this.disableClose))
       .subscribe(() => this.close());
+
+    if (location) {
+      // Close the dialog when the user goes forwards/backwards in history or when the location
+      // hash changes. Note that this usually doesn't include clicking on links (unless the user
+      // is using the `HashLocationStrategy`).
+      this._locationChanges = location.subscribe(() => {
+        if (this._containerInstance._config.closeOnNavigation) {
+          this.close();
+        }
+      });
+    }
   }
 
   /**

src/lib/dialog/dialog.spec.ts

@@ -582,6 +582,19 @@ describe('MatDialog', () => {
     expect(overlayContainerElement.querySelectorAll('mat-dialog-container').length).toBe(0);
   }));
 
+  it('should allow the consumer to disable closing a dialog on navigation', fakeAsync(() => {
+    dialog.open(PizzaMsg);
+    dialog.open(PizzaMsg, {closeOnNavigation: false});
+
+    expect(overlayContainerElement.querySelectorAll('mat-dialog-container').length).toBe(2);
+
+    mockLocation.simulateUrlPop('');
+    viewContainerFixture.detectChanges();
+    flush();
+
+    expect(overlayContainerElement.querySelectorAll('mat-dialog-container').length).toBe(1);
+  }));
+
   it('should have the componentInstance available in the afterClosed callback', fakeAsync(() => {
     let dialogRef = dialog.open(PizzaMsg);
     let spy = jasmine.createSpy('afterClosed spy');

src/lib/dialog/dialog.ts

@@ -96,19 +96,11 @@ export class MatDialog {
   constructor(
       private _overlay: Overlay,
       private _injector: Injector,
-      @Optional() location: Location,
+      @Optional() private _location: Location,
       @Optional() @Inject(MAT_DIALOG_DEFAULT_OPTIONS) private _defaultOptions,
       @Inject(MAT_DIALOG_SCROLL_STRATEGY) private _scrollStrategy,
       @Optional() @SkipSelf() private _parentDialog: MatDialog,
-      private _overlayContainer: OverlayContainer) {
-
-    // Close all of the dialogs when the user goes forwards/backwards in history or when the
-    // location hash changes. Note that this usually doesn't include clicking on links (unless
-    // the user is using the `HashLocationStrategy`).
-    if (!_parentDialog && location) {
-      location.subscribe(() => this.closeAll());
-    }
-  }
+      private _overlayContainer: OverlayContainer) {}
 
   /**
    * Opens a modal dialog containing the given component.
@@ -232,7 +224,7 @@ export class MatDialog {
 
     // Create a reference to the dialog we're creating in order to give the user a handle
     // to modify and close it.
-    const dialogRef = new MatDialogRef<T>(overlayRef, dialogContainer, config.id);
+    const dialogRef = new MatDialogRef<T>(overlayRef, dialogContainer, this._location, config.id);
 
     // When the dialog backdrop is clicked, we want to close it.
     if (config.hasBackdrop) {