Adds exception for .distinct() to behave a little different from othe…

…r aggregate functions (#123)

lib/AggregateFunctions.js

@@ -8,8 +8,9 @@ function AggregateFunctions(opts) {
 		throw new Error("This driver does not support aggregate functions");
 	}
 
-	var aggregates = [ [] ];
-	var group_by   = null;
+	var aggregates    = [ [] ];
+	var group_by      = null;
+	var used_distinct = false;
 
 	var appendFunction = function (fun) {
 		return function () {
@@ -22,6 +23,10 @@ function AggregateFunctions(opts) {
 				aggregates[aggregates.length - 1].push({ f: fun, alias: aggregateAlias(fun, args) });
 			}
 
+			if (fun == "distinct") {
+				used_distinct = true;
+			}
+
 			return proto;
 		};
 	};
@@ -92,9 +97,17 @@ function AggregateFunctions(opts) {
 					return cb(null, data);
 				}
 
-				var items = [];
+				var items = [], i;
+
+				if (used_distinct && aggregates.length == 1) {
+					for (i = 0; i < data.length; i++) {
+						items.push(data[i][Object.keys(data[i]).pop()]);
+					}
+
+					return cb(null, items);
+				}
 
-				for (var i = 0; i < aggregates.length; i++) {
+				for (i = 0; i < aggregates.length; i++) {
 					for (var j = 0; j < aggregates[i].length; j++) {
 						items.push(data[0][aggregates[i][j].alias] || null);
 					}

test/integration/test-aggregate-distinct.js

@@ -0,0 +1,25 @@
+var common     = require('../common');
+var assert     = require('assert');
+
+common.createConnection(function (err, db) {
+	common.createModelTable('test_aggregate_distinct', db.driver.db, function () {
+		common.insertModelData('test_aggregate_distinct', db.driver.db, [
+			{ id : 1, name : 'test1' },
+			{ id : 2, name : 'test1' },
+			{ id : 3, name : 'test2' },
+			{ id : 4, name : 'test2' },
+			{ id : 5, name : 'test2' }
+		], function (err) {
+			if (err) throw err;
+
+			var TestModel = db.define('test_aggregate_distinct', common.getModelProperties());
+
+			TestModel.aggregate().distinct('name').get(function (err, names) {
+				assert.equal(err, null);
+				assert.equal(Array.isArray(names), true);
+				assert.equal(names.length, 2);
+				db.close();
+			});
+		});
+	});
+});