Update function updates updatedAt field if necessary

lib/datastore.js

@@ -539,13 +539,14 @@ Datastore.prototype._update = function (query, updateQuery, options, cb) {
 	  , modifications = []
 	  ;
 
-	// Preparing update (if an error is thrown here neither the datafile nor
+    // Preparing update (if an error is thrown here neither the datafile nor
-	// the in-memory indexes are affected)
+    // the in-memory indexes are affected)
     try {
       for (i = 0; i < candidates.length; i += 1) {
         if (model.match(candidates[i], query) && (multi || numReplaced === 0)) {
           numReplaced += 1;
           modifiedDoc = model.modify(candidates[i], updateQuery);
+          if (self.timestampData) { modifiedDoc.updatedAt = new Date(); }
           modifications.push({ oldDoc: candidates[i], newDoc: modifiedDoc });
         }
       }
@@ -553,14 +554,14 @@ Datastore.prototype._update = function (query, updateQuery, options, cb) {
       return callback(err);
     }
 
-	// Change the docs in memory
+    // Change the docs in memory
-	try {
+    try {
-      self.updateIndexes(modifications);
+        self.updateIndexes(modifications);
-	} catch (err) {
+    } catch (err) {
-	  return callback(err);
+      return callback(err);
-	}
+    }
 
-	// Update the datafile
+    // Update the datafile
     self.persistence.persistNewState(_.pluck(modifications, 'newDoc'), function (err) {
       if (err) { return callback(err); }
       return callback(null, numReplaced);

test/db.test.js

@@ -957,6 +957,34 @@ describe('Database', function () {
       ], done);
     });
 
+    it("If timestampData option is set, update the updatedAt field", function (done) {
+      var beginning = Date.now();
+      d = new Datastore({ filename: testDb, autoload: true, timestampData: true });
+      d.insert({ hello: 'world' }, function (err, insertedDoc) {
+        assert.isBelow(insertedDoc.updatedAt.getTime() - beginning, 15);
+        assert.isBelow(insertedDoc.createdAt.getTime() - beginning, 15);
+        Object.keys(insertedDoc).length.should.equal(4);
+
+        // Wait 100ms before performing the update
+        setTimeout(function () {
+          var step1 = Date.now();
+          d.update({ _id: insertedDoc._id }, { $set: { hello: 'mars' } }, {}, function () {
+            d.find({ _id: insertedDoc._id }, function (err, docs) {
+              docs.length.should.equal(1);
+              Object.keys(docs[0]).length.should.equal(4);
+              docs[0]._id.should.equal(insertedDoc._id);
+              docs[0].createdAt.should.equal(insertedDoc.createdAt);
+              docs[0].hello.should.equal('mars');
+              assert.isAbove(docs[0].updatedAt.getTime() - beginning, 99);   // updatedAt modified
+              assert.isBelow(docs[0].updatedAt.getTime() - step1, 15);   // updatedAt modified
+
+              done();
+            });
+          })
+        }, 100);
+      });
+    });
+
     it("Can update multiple documents matching the query", function (done) {
       var id1, id2, id3;