fix(afs): Allow multiple subscribers by using share, closes #1191

src/firestore/collection/changes.ts

@@ -5,6 +5,7 @@ import { Observable } from 'rxjs/Observable';
 import 'rxjs/add/operator/map';
 import 'rxjs/add/operator/filter';
 import 'rxjs/add/operator/scan';
+import 'rxjs/add/operator/shareReplay';
 
 import { DocumentChangeAction, Action } from '../interfaces';
 
@@ -28,7 +29,8 @@ export function sortedChanges(query: firebase.firestore.Query, events: firebase.
   return fromCollectionRef(query)
     .map(changes => changes.payload.docChanges)
     .scan((current, changes) => combineChanges(current, changes, events), [])
-    .map(changes => changes.map(c => ({ type: c.type, payload: c })));
+    .map(changes => changes.map(c => ({ type: c.type, payload: c })))
+    .shareReplay(1);
 }
 
 /**

src/firestore/collection/collection.spec.ts

@@ -75,6 +75,49 @@ describe('AngularFirestoreCollection', () => {
 
     });
 
+    it('should handle multiple subscriptions (hot)', async (done: any) => {
+      const ITEMS = 4;
+      const { randomCollectionName, ref, stocks, names } = await collectionHarness(afs, ITEMS);
+      const changes = stocks.valueChanges();
+      const sub = changes.subscribe(() => {}).add(
+        changes.take(1).subscribe(data => {
+          expect(data.length).toEqual(ITEMS);
+          sub.unsubscribe();
+        })
+      ).add(() => {
+        deleteThemAll(names, ref).then(done).catch(done.fail);
+      });
+    });
+
+    // We need a clean way of handling now that we are no longer filtering empty
+    xit('should handle multiple subscriptions (warm)', async (done: any) => {
+      const ITEMS = 4;
+      const { randomCollectionName, ref, stocks, names } = await collectionHarness(afs, ITEMS);
+      const changes = stocks.valueChanges();
+      changes.take(1).subscribe(() => {}).add(() => {
+        const sub = changes.take(1).subscribe(data => {
+          expect(data.length).toEqual(ITEMS);
+        }).add(() => {
+          deleteThemAll(names, ref).then(done).catch(done.fail);
+        });
+      });
+    });
+
+    it('should handle multiple subscriptions (cold)', async (done: any) => {
+      const ITEMS = 4;
+      const { randomCollectionName, ref, stocks, names } = await collectionHarness(afs, ITEMS);
+      const changes = stocks.valueChanges();
+      const sub = changes.subscribe(() => {
+        sub.unsubscribe();
+      }).add(() => {
+        changes.take(1).subscribe(data => {
+          expect(data.length).toEqual(ITEMS);
+        }).add(() => {
+          deleteThemAll(names, ref).then(done).catch(done.fail);
+        });
+      });
+    });
+
     it('should handle dynamic queries that return empty sets', async (done) => {
       const ITEMS = 10;
       let count = 0;
@@ -129,6 +172,20 @@ describe('AngularFirestoreCollection', () => {
       });
     });
 
+    it('should handle multiple subscriptions', async (done: any) => {
+      const ITEMS = 4;
+      const { randomCollectionName, ref, stocks, names } = await collectionHarness(afs, ITEMS);
+      const changes = stocks.snapshotChanges();
+      const sub = changes.subscribe(() => {}).add(
+        changes.take(1).subscribe(data => {
+          expect(data.length).toEqual(ITEMS);
+          sub.unsubscribe();
+        })
+      ).add(() => {
+        deleteThemAll(names, ref).then(done).catch(done.fail);
+      });
+    });
+
     it('should update order on queries', async (done) => {
       const ITEMS = 10;
       let count = 0;

src/firestore/observable/fromRef.ts

@@ -5,7 +5,9 @@ import { Subscription } from 'rxjs/Subscription';
 import { observeOn } from 'rxjs/operator/observeOn';
 import { ZoneScheduler } from 'angularfire2';
 import { Action, Reference } from '../interfaces';
+
 import 'rxjs/add/operator/map';
+import 'rxjs/add/operator/share';
 
 function _fromRef<T, R>(ref: Reference<T>): Observable<R> {
   const ref$ = new Observable(subscriber => {
@@ -16,7 +18,7 @@ function _fromRef<T, R>(ref: Reference<T>): Observable<R> {
 }
 
 export function fromRef<R>(ref: firebase.firestore.DocumentReference | firebase.firestore.Query) {
-  return _fromRef<typeof ref, R>(ref);
+  return _fromRef<typeof ref, R>(ref).share();
 }
 
 export function fromDocRef(ref: firebase.firestore.DocumentReference): Observable<Action<firebase.firestore.DocumentSnapshot>>{

tools/build.js

@@ -44,6 +44,8 @@ const GLOBALS = {
   'rxjs/add/observable/fromPromise': 'Rx.Observable.prototype',
   'rxjs/add/operator/delay': 'Rx.Observable',
   'rxjs/add/operator/debounce': 'Rx.Observable',
+  'rxjs/add/operator/shareReplay': 'Rx.Observable',
+  'rxjs/add/operator/share': 'Rx.Observable',
   'rxjs/observable/fromEvent': 'Rx.Observable',
   'rxjs/observable/from': 'Rx.Observable',
   'rxjs/operator': 'Rx.Observable.prototype',