datastore: use millisecond-precision with stored dates (#1611)

Author: stephenplusplus

src/entity.js

@@ -191,7 +191,8 @@ function decodeValueProto(valueProto) {
     }
 
     case 'timestampValue': {
-      return new Date(parseInt(value.seconds, 10) * 1000);
+      var milliseconds = parseInt(value.nanos, 10) / 1e6;
+      return new Date(parseInt(value.seconds, 10) * 1000 + milliseconds);
     }
 
     default: {
@@ -252,11 +253,10 @@ function encodeValue(value) {
 
   if (value instanceof Date) {
     var seconds = value.getTime() / 1000;
-    var secondsRounded = Math.floor(seconds);
 
     valueProto.timestampValue = {
-      seconds: secondsRounded,
-      nanos: Math.floor((seconds - secondsRounded) * 1e9)
+      seconds: Math.floor(seconds),
+      nanos: value.getMilliseconds() * 1e6
     };
 
     return valueProto;

system-test/datastore.js

@@ -71,7 +71,7 @@ describe('Datastore', function() {
     var post = {
       title: 'How to make the perfect pizza in your grill',
       tags: ['pizza', 'grill'],
-      publishedAt: new Date(2001, 0, 1),
+      publishedAt: new Date(),
       author: 'Silvano',
       isDraft: false,
       wordCount: 400,

test/entity.js

@@ -218,13 +218,18 @@ describe('entity', function() {
     });
 
     it('should decode timestamps', function() {
-      var seconds = String(Date.now() / 1000);
-      var expectedValue = new Date(parseInt(seconds, 10) * 1000);
+      var date = new Date();
+
+      var seconds = Math.floor(date.getTime() / 1000);
+      var ms = date.getMilliseconds();
+
+      var expectedValue = new Date(seconds * 1000 + ms);
 
       var valueProto = {
         value_type: 'timestampValue',
         timestampValue: {
-          seconds: seconds
+          seconds: seconds,
+          nanos: ms * 1e6
         }
       };
 
@@ -327,12 +332,11 @@ describe('entity', function() {
     it('should encode a date', function() {
       var value = new Date();
       var seconds = value.getTime() / 1000;
-      var secondsRounded = Math.floor(seconds);
 
       var expectedValueProto = {
         timestampValue: {
-          seconds: secondsRounded,
-          nanos: Math.floor((seconds - secondsRounded) * 1e9)
+          seconds: Math.floor(seconds),
+          nanos: value.getMilliseconds() * 1e6
         }
       };