datastore: Avoid clearing offset when start cursor is set

README.md

@@ -210,9 +210,9 @@ Pagination allows you to set an offset, limit and starting cursor to a query.
 
 ~~~~ js
 var q = ds.createQuery('Company')
-    .offset(100) // start from 101th result
-    .limit(10)   // return only 10 results
     .start(cursorToken); // continue to retrieve results from the given cursor.
+    .offset(100) // start from the 101th result after start cursor.
+    .limit(10)   // return only 10 results
 ~~~~
 
 #### Allocating IDs (ID generation)

lib/datastore/index.js

@@ -219,7 +219,7 @@ Transaction.prototype.runQuery = function(q, opt_callback) {
     }
     var nextQuery = null;
     if (resp.batch.endCursor && resp.batch.endCursor != q.startVal) {
-      nextQuery = q.start(resp.batch.endCursor);
+      nextQuery = q.start(resp.batch.endCursor).offset(0);
     }
     opt_callback(null, entity.formatArray(resp.batch.entityResults), nextQuery);
   });

lib/datastore/query.js

@@ -76,7 +76,6 @@ Query.prototype.select = function(fieldNames) {
 Query.prototype.start = function(start) {
   var q = util.extend(this, new Query());
   q.startVal = start;
-  q.offsetVal = 0;
   return q;
 }
 

test/datastore.query.js

@@ -112,13 +112,6 @@ describe('Query', function() {
     done();
   });
 
-  it('should reset the offset to 0 when using start tokens', function(done) {
-    var q = ds.createQuery(['kind1']).offset(5);
-    q.start('startVal');
-    assert.strictEqual(q.offsetVal, 0);
-    done();
-  });
-
   it('should be converted to a query proto successfully', function(done) {
     var q = ds.createQuery(['Kind'])
         .select(['name', 'count'])