Adds AggregateFunctions.limit() and changes Readme to avoid confusion (…

…#172)

Readme.md

@@ -437,27 +437,32 @@ Person.aggregate({ surname: "Doe" }).min("age").max("age").get(function (err, mi
 	console.log("The youngest Doe guy has %d years, while the oldest is %d", min, max);
 });
 ```
-Here's an example to illustrate how to use groupby:
+
+An `Array` of properties can be passed to select only a few properties. An `Object` is also accepted to define conditions.
+
+Here's an example to illustrate how to use `.groupBy()`:
+
 ```js
 //The same as "select avg(weight), age from person where country='someCountry' group by age;"
 Person.aggregate(["age"], { country: "someCountry" }).avg("weight").groupBy("age").get(function (err, stats) {
     // stats is an Array, each item should have 'age' and 'avg_weight'
 });
 ```
 
-Possible aggregating functions:
+### Base `.aggregate()` methods
+
+- `.limit()`: you can pass a number as a limit, or two numbers as offset and limit respectively
+- `.order()`: same as `Model.find().order()`
+
+### Additional `.aggregate()` methods
 
 - `min`
 - `max`
 - `avg`
 - `sum`
 - `count` (there's a shortcut to this - `Model.count`)
 
-### Available options
-
-- `offset`: discards the first `N` elements
-- `limit`: although it can be passed as a direct argument, you can use it here if you prefer
-- `only`: if you don't want all properties, you can give an array with the list of properties you want
+There are more aggregate functions depending on the driver (Math functions for example).
 
 #### Chaining
 

lib/AggregateFunctions.js

@@ -35,6 +35,14 @@ function AggregateFunctions(opts) {
 			group_by = Array.prototype.slice.apply(arguments);
 			return this;
 		},
+		limit: function (offset, limit) {
+			if (typeof limit == "number") {
+				opts.limit = [ offset, limit ];
+			} else {
+				opts.limit = [ 0, offset ]; // offset = limit
+			}
+			return this;
+		},
 		order: function (property, order) {
 			opts.order = [ property, order ];
 			return this;
@@ -87,6 +95,9 @@ function AggregateFunctions(opts) {
 			if (opts.order) {
 				query.order.apply(query, opts.order);
 			}
+			if (opts.limit) {
+				query.offset(opts.limit[0]).limit(opts.limit[1]);
+			}
 
 			opts.driver.execQuery(query.build(), function (err, data) {
 				if (err) {

test/integration/test-aggregate-limit.js

@@ -0,0 +1,27 @@
+var common     = require('../common');
+var assert     = require('assert');
+
+common.createConnection(function (err, db) {
+	common.createModelTable('test_aggregate_limit', db.driver.db, function () {
+		common.insertModelData('test_aggregate_limit', db.driver.db, [
+			{ id : 1, name : 'test1' },
+			{ id : 2, name : 'test1' },
+			{ id : 3, name : 'test2' },
+			{ id : 4, name : 'test2' },
+			{ id : 5, name : 'test2' },
+			{ id : 6, name : 'test3' },
+			{ id : 7, name : 'test3' }
+		], function (err) {
+			if (err) throw err;
+
+			var TestModel = db.define('test_aggregate_limit', common.getModelProperties());
+
+			TestModel.aggregate().distinct('name').limit(1).get(function (err, names) {
+				assert.equal(err, null);
+				assert.equal(Array.isArray(names), true);
+				assert.equal(names.length, 1);
+				db.close();
+			});
+		});
+	});
+});