Handle Firestore timestamp values with varying degrees of precision (#123)

Author: laurenzlong

spec/providers/firestore.spec.ts

@@ -295,7 +295,7 @@ describe('Firestore Functions', () => {
         expect(snapshot.data()['referenceVal'].path).to.equal('doc1/id');
       });
 
-      it('should parse timestamp values', () => {
+      it('should parse timestamp values with precision to the millisecond', () => {
         let raw = constructValue({
           'timestampVal': {
             'timestampValue': '2017-06-13T00:58:40.349Z',
@@ -307,6 +307,19 @@ describe('Firestore Functions', () => {
         expect(snapshot.data()).to.deep.equal({'timestampVal': new Date('2017-06-13T00:58:40.349Z')});
       });
 
+      it('should parse timestamp values with precision to the second', () => {
+        let raw = constructValue({
+          'timestampVal': {
+            'timestampValue': '2017-06-13T00:58:40Z',
+          },
+        });
+        let snapshot = firestore.dataConstructor({
+          data: { value: raw },
+        });
+        expect(snapshot.data()).to.deep.equal({'timestampVal': new Date('2017-06-13T00:58:40Z')});
+
+      });
+
       it('should parse binary values', () => {
         // Format defined in https://developers.google.com/discovery/v1/type-format
         let raw = constructValue({

src/encoder.ts

@@ -26,16 +26,11 @@ export function dateToTimestampProto(timeString) {
   }
   let date = new Date(timeString);
   let seconds = Math.floor(date.getTime() / 1000);
-  let nanoString = timeString.substring(20, timeString.length - 1);
-
-  if (nanoString.length === 3) {
-    nanoString = `${nanoString}000000`;
-  } else if (nanoString.length === 6)  {
-    nanoString = `${nanoString}000`;
+  let nanos = 0;
+  if (timeString.length > 20) {
+    const nanoString = timeString.substring(20, timeString.length - 1);
+    const trailingZeroes = 9 - nanoString.length;
+    nanos = parseInt(nanoString, 10) * Math.pow(10, trailingZeroes);
   }
-  let proto = {
-    seconds: seconds,
-    nanos: parseInt(nanoString, 10),
-  };
-  return proto;
+  return { seconds, nanos };
 };