Support instance selection for database functions (#171)

Author: laurenzlong

package.json

@@ -38,7 +38,7 @@
     "@types/sinon": "^1.16.29",
     "chai": "^3.5.0",
     "chai-as-promised": "^5.2.0",
-    "firebase-admin": "^5.4.2",
+    "firebase-admin": "~5.5.0",
     "istanbul": "^0.4.2",
     "mocha": "^2.4.5",
     "mock-require": "^2.0.1",
@@ -48,7 +48,7 @@
     "typescript": "^2.0.3"
   },
   "peerDependencies": {
-    "firebase-admin": "~5.4.2"
+    "firebase-admin": "~5.5.0"
   },
   "dependencies": {
     "@types/express": "^4.0.33",

spec/providers/database.spec.ts

@@ -49,6 +49,12 @@ describe('DatabaseBuilder', () => {
       expect(resource).to.eq('projects/_/instances/subdomain/refs/foo');
     });
 
+    it('should let developers choose a database instance', () => {
+      let func = database.instance('custom').ref('foo').onWrite(() => null);
+      let resource = func.__trigger.eventTrigger.resource;
+      expect(resource).to.eq('projects/_/instances/custom/refs/foo');
+    });
+
     it('should return a handler that emits events with a proper DeltaSnapshot', () => {
       let handler = database.ref('/users/{id}').onWrite(event => {
         expect(event.data.val()).to.deep.equal({ foo: 'bar' });
@@ -75,6 +81,12 @@ describe('DatabaseBuilder', () => {
       expect(resource).to.eq('projects/_/instances/subdomain/refs/foo');
     });
 
+    it('should let developers choose a database instance', () => {
+      let func = database.instance('custom').ref('foo').onCreate(() => null);
+      let resource = func.__trigger.eventTrigger.resource;
+      expect(resource).to.eq('projects/_/instances/custom/refs/foo');
+    });
+
     it('should return a handler that emits events with a proper DeltaSnapshot', () => {
       let handler = database.ref('/users/{id}').onCreate(event => {
         expect(event.data.val()).to.deep.equal({ foo: 'bar' });
@@ -101,6 +113,12 @@ describe('DatabaseBuilder', () => {
       expect(resource).to.eq('projects/_/instances/subdomain/refs/foo');
     });
 
+    it('should let developers choose a database instance', () => {
+      let func = database.instance('custom').ref('foo').onUpdate(() => null);
+      let resource = func.__trigger.eventTrigger.resource;
+      expect(resource).to.eq('projects/_/instances/custom/refs/foo');
+    });
+
     it('should return a handler that emits events with a proper DeltaSnapshot', () => {
       let handler = database.ref('/users/{id}').onUpdate(event => {
         expect(event.data.val()).to.deep.equal({ foo: 'bar' });
@@ -127,6 +145,12 @@ describe('DatabaseBuilder', () => {
       expect(resource).to.eq('projects/_/instances/subdomain/refs/foo');
     });
 
+    it('should let developers choose a database instance', () => {
+      let func = database.instance('custom').ref('foo').onDelete(() => null);
+      let resource = func.__trigger.eventTrigger.resource;
+      expect(resource).to.eq('projects/_/instances/custom/refs/foo');
+    });
+
     it('should return a handler that emits events with a proper DeltaSnapshot', () => {
       let handler = database.ref('/users/{id}').onDelete(event => {
         expect(event.data.val()).to.deep.equal({ foo: 'bar' });
@@ -144,20 +168,44 @@ describe('DatabaseBuilder', () => {
 
 });
 
+describe('resourceToInstanceAndPath', () => {
+  it('should return the correct instance and path strings', () => {
+    let [instance, path] = database.resourceToInstanceAndPath('projects/_/instances/foo/refs/bar');
+    expect(instance).to.equal('https://foo.firebaseio.com');
+    expect(path).to.equal('/bar');
+  });
+});
+
 describe('DeltaSnapshot', () => {
   let subject;
   const apps = new appsNamespace.Apps(fakeConfig());
 
   let populate = (old: any, change: any) => {
+    let [instance, path] = database.resourceToInstanceAndPath('projects/_/instances/other-subdomain/refs/foo');
     subject = new database.DeltaSnapshot(
       apps.admin,
       apps.admin,
+      instance,
       old,
       change,
-      database.resourceToPath('projects/_/instances/mySubdomain/refs/foo')
+      path
     );
   };
 
+  describe('#ref: firebase.database.Reference', () => {
+    it('should return a ref for correct instance, not the default instance', () => {
+      populate({}, {});
+      expect(subject.ref.toJSON()).to.equal('https://other-subdomain.firebaseio.com/foo');
+    });
+  });
+
+  describe('#adminRef(): firebase.database.Reference', () => {
+    it('should return an adminRef for correct instance, not the default instance', () => {
+      populate({}, {});
+      expect(subject.adminRef.toJSON()).to.equal('https://other-subdomain.firebaseio.com/foo');
+    });
+  });
+
   describe('#val(): any', () => {
     it('should return child values based on the child path', () => {
       populate({ a: { b: 'c' } }, { a: { d: 'e' } });
@@ -372,23 +420,27 @@ describe('DeltaSnapshot', () => {
     });
 
     it('should return null for the root', () => {
+      let [instance, path] = database.resourceToInstanceAndPath('projects/_/instances/refs/refs');
       const snapshot = new database.DeltaSnapshot(
         apps.admin,
         apps.admin,
+        instance,
         null,
         null,
-        database.resourceToPath('projects/_/instances/foo/refs')
+        path
       );
       expect(snapshot.key).to.be.null;
     });
 
     it('should return null for explicit root', () => {
+      let [instance, path] = database.resourceToInstanceAndPath('projects/_/instances/refs/refs');
       expect(new database.DeltaSnapshot(
         apps.admin,
         apps.admin,
+        instance,
         null,
         {},
-        database.resourceToPath('projects/_/instances/foo/refs')
+        path
       ).key).to.be.null;
     });
 

src/providers/database.ts

@@ -33,6 +33,22 @@ export const provider = 'google.firebase.database';
 // NOTE(inlined): Should we relax this a bit to allow staging or alternate implementations of our API?
 const databaseURLRegex = new RegExp('https://([^.]+).firebaseio.com');
 
+/**
+ * Pick the Realtime Database instance to use. If omitted, will pick the default database for your project.
+ */
+export function instance(instance: string): InstanceBuilder {
+  return new InstanceBuilder(instance);
+}
+
+export class InstanceBuilder {
+  /* @internal */
+  constructor(private instance: string) {}
+
+  ref(path: string): RefBuilder {
+    return new RefBuilder(apps(), `projects/_/instances/${this.instance}/refs/${path}`);
+  }
+}
+
 /**
  * Handle events at a Firebase Realtime Database Reference.
  *
@@ -75,7 +91,7 @@ export function ref(path: string): RefBuilder {
 /** Builder used to create Cloud Functions for Firebase Realtime Database References. */
 export class RefBuilder {
   /** @internal */
-  constructor(private apps: apps.Apps, private resource) { }
+  constructor(private apps: apps.Apps, private resource: string) { }
 
   /** Respond to any write that affects a ref. */
   onWrite(handler: (event: Event<DeltaSnapshot>) => PromiseLike<any> | any): CloudFunction<DeltaSnapshot> {
@@ -105,12 +121,14 @@ export class RefBuilder {
       if (raw.data instanceof DeltaSnapshot) {
         return raw.data;
       }
+      let [dbInstance, path] = resourceToInstanceAndPath(raw.resource);
       return new DeltaSnapshot(
         this.apps.forMode(raw.auth),
         this.apps.admin,
+        dbInstance,
         raw.data.data,
         raw.data.delta,
-        resourceToPath(raw.resource),
+        path,
       );
     };
     return makeCloudFunction({
@@ -126,21 +144,22 @@ export class RefBuilder {
 
 /* Utility function to extract database reference from resource string */
 /** @internal */
-export function resourceToPath(resource) {
+export function resourceToInstanceAndPath(resource) {
   let resourceRegex = `projects/([^/]+)/instances/([^/]+)/refs(/.+)?`;
   let match = resource.match(new RegExp(resourceRegex));
   if (!match) {
     throw new Error(`Unexpected resource string for Firebase Realtime Database event: ${resource}. ` +
       'Expected string in the format of "projects/_/instances/{firebaseioSubdomain}/refs/{ref=**}"');
   }
-  let [, project, /* instance */, path] = match;
+  let [, project, dbInstanceName, path] = match;
   if (project !== '_') {
     throw new Error(`Expect project to be '_' in a Firebase Realtime Database event`);
   }
-  return path;
+  let dbInstance = 'https://' + dbInstanceName + '.firebaseio.com';
+  return [dbInstance, path];
 }
 
-export class DeltaSnapshot implements firebase.database.DataSnapshot {
+export class DeltaSnapshot {
   private _adminRef: firebase.database.Reference;
   private _ref: firebase.database.Reference;
   private _path: string;
@@ -154,6 +173,7 @@ export class DeltaSnapshot implements firebase.database.DataSnapshot {
   constructor(
     private app: firebase.app.App,
     private adminApp: firebase.app.App,
+    private instance: string,
     data: any,
     delta: any,
     path?: string // path will be undefined for the database root
@@ -168,14 +188,14 @@ export class DeltaSnapshot implements firebase.database.DataSnapshot {
 
   get ref(): firebase.database.Reference {
     if (!this._ref) {
-      this._ref = this.app.database().ref(this._fullPath());
+      this._ref = this.app.database(this.instance).ref(this._fullPath());
     }
     return this._ref;
   }
 
   get adminRef(): firebase.database.Reference {
     if (!this._adminRef) {
-      this._adminRef = this.adminApp.database().ref(this._fullPath());
+      this._adminRef = this.adminApp.database(this.instance).ref(this._fullPath());
     }
     return this._adminRef;
   }
@@ -291,7 +311,7 @@ export class DeltaSnapshot implements firebase.database.DataSnapshot {
   }
 
   private _dup(previous: boolean, childPath?: string): DeltaSnapshot {
-    let dup = new DeltaSnapshot(this.app, this.adminApp, undefined, undefined);
+    let dup = new DeltaSnapshot(this.app, this.adminApp, this.instance, undefined, undefined);
     [dup._path, dup._data, dup._delta, dup._childPath, dup._newData] =
       [this._path, this._data, this._delta, this._childPath, this._newData];