NODE-993 Expose hasNext for command cursor and add docs for both Comm…

…andCursor and Aggregation Cursor

lib/aggregation_cursor.js

@@ -316,6 +316,7 @@ AggregationCursor.prototype.get = AggregationCursor.prototype.toArray;
 define.classMethod('toArray', {callback: true, promise:true});
 define.classMethod('each', {callback: true, promise:false});
 define.classMethod('forEach', {callback: true, promise:false});
+define.classMethod('hasNext', {callback: true, promise:true});
 define.classMethod('next', {callback: true, promise:true});
 define.classMethod('close', {callback: true, promise:true});
 define.classMethod('isClosed', {callback: false, promise:false, returns: [Boolean]});
@@ -331,6 +332,14 @@ define.classMethod('readBufferedDocuments', {callback: false, promise:false, ret
  * @return {Promise} returns Promise if no callback passed
  */
 
+/**
+ * Check if there is any document still available in the cursor
+ * @function AggregationCursor.prototype.hasNext
+ * @param {AggregationCursor~resultCallback} [callback] The result callback.
+ * @throws {MongoError}
+ * @return {Promise} returns Promise if no callback passed
+ */
+
 /**
  * The callback format for results
  * @callback AggregationCursor~toArrayResultCallback

lib/command_cursor.js

@@ -131,7 +131,7 @@ var CommandCursor = function(bson, ns, cmd, options, topology, topologyOptions)
 inherits(CommandCursor, Readable);
 
 // Set the methods to inherit from prototype
-var methodsToInherit = ['_next', 'next', 'each', 'forEach', 'toArray'
+var methodsToInherit = ['_next', 'next', 'hasNext', 'each', 'forEach', 'toArray'
   , 'rewind', 'bufferedCount', 'readBufferedDocuments', 'close', 'isClosed', 'kill', 'setCursorBatchSize'
   , '_find', '_getmore', '_killcursor', 'isDead', 'explain', 'isNotified', 'isKilled'];
 
@@ -207,6 +207,7 @@ define.classMethod('toArray', {callback: true, promise:true});
 define.classMethod('each', {callback: true, promise:false});
 define.classMethod('forEach', {callback: true, promise:false});
 define.classMethod('next', {callback: true, promise:true});
+define.classMethod('hasNext', {callback: true, promise:true});
 define.classMethod('close', {callback: true, promise:true});
 define.classMethod('isClosed', {callback: false, promise:false, returns: [Boolean]});
 define.classMethod('rewind', {callback: false, promise:false});
@@ -221,6 +222,14 @@ define.classMethod('readBufferedDocuments', {callback: false, promise:false, ret
  * @return {Promise} returns Promise if no callback passed
  */
 
+/**
+ * Check if there is any document still available in the cursor
+ * @function CommandCursor.prototype.hasNext
+ * @param {CommandCursor~resultCallback} [callback] The result callback.
+ * @throws {MongoError}
+ * @return {Promise} returns Promise if no callback passed
+ */
+
 /**
  * The callback format for results
  * @callback CommandCursor~toArrayResultCallback

test/functional/aggregation_tests.js

@@ -826,4 +826,51 @@ exports['Should correctly handle ISODate date matches in aggregation framework']
     });
     // DOC_END
   }
+}
+
+/**
+ * Correctly call the aggregation framework to return a cursor with batchSize 1 and get the first result using next
+ *
+ * @ignore
+ */
+exports['Should correctly exercise hasNext function on aggregation cursor'] = {
+  metadata: {
+    requires: {
+        mongodb: ">=2.6.0"
+      , topology: 'single'
+      , node: ">0.10.0"
+    }
+  },
+
+  // The actual test we wish to run
+  test: function(configure, test) {
+    var db = configure.newDbInstance({w:1}, {poolSize:1});
+
+    // DOC_LINE var db = new Db('test', new Server('localhost', 27017));
+    // DOC_START
+    db.open(function(err, db) {
+      // Create a collection
+      var collection = db.collection('shouldCorrectlyQueryUsingISODate3');
+      // Insert the docs
+      collection.insertMany([
+        {a:1}, {b:1}
+      ], {w: 1}, function(err, result) {
+
+        // Execute aggregate, notice the pipeline is expressed as an Array
+        var cursor = collection.aggregate([{
+          $match: {}
+        }]);
+
+        // Iterate over all the items in the cursor
+        cursor.hasNext(function(err, result) {
+          test.equal(null, err);
+          test.equal(true, result);
+
+          db.close();
+          test.done();
+        });
+      });
+    });
+    // DOC_END
+  }
 }

test/functional/index_tests.js

@@ -672,6 +672,29 @@ exports['should correctly use listIndexes to retrieve index list'] = {
   }
 }
 
+exports['should correctly use listIndexes to retrieve index list using hasNext'] = {
+  metadata: { requires: { mongodb: ">=2.4.0", topology: ['single', 'ssl', 'heap', 'wiredtiger'] } },
+
+  // The actual test we wish to run
+  test: function(configuration, test) {
+    var db = configuration.newDbInstance(configuration.writeConcernMax(), {poolSize:1});
+    db.open(function(err, db) {
+      db.collection('testListIndexes_2').ensureIndex({a:1}, function(err, r) {
+        test.equal(null, err);
+
+        // Get the list of indexes
+        db.collection('testListIndexes_2').listIndexes().hasNext(function(err, result) {
+          test.equal(null, err);
+          test.equal(true, result);
+
+          db.close();
+          test.done();
+        });
+      });
+    });
+  }
+}
+
 exports['should correctly ensureIndex for nested style index name c.d'] = {
   metadata: { requires: { mongodb: ">=2.4.0", topology: ['single', 'ssl', 'heap', 'wiredtiger'] } },