Use aggregations for pagination, fixes #437 and #428

Author: jenssegers

src/Jenssegers/Mongodb/Query/Builder.php

@@ -29,6 +29,13 @@ class Builder extends BaseBuilder {
      */
     public $timeout;
 
+    /**
+     * Indicate if we are executing a pagination query.
+     *
+     * @var bool
+     */
+    public $paginating = false;
+
     /**
      * All of the available clause operators.
      *
@@ -140,7 +147,7 @@ public function getFresh($columns = array())
         $wheres = $this->compileWheres();
 
         // Use MongoDB's aggregation framework when using grouping or aggregation functions.
-        if ($this->groups or $this->aggregate)
+        if ($this->groups or $this->aggregate or $this->paginating)
         {
             $group = array();
 
@@ -155,12 +162,14 @@ public function getFresh($columns = array())
                     // this mimics MySQL's behaviour a bit.
                     $group[$column] = array('$last' => '$' . $column);
                 }
-            }
-            else
-            {
-                // If we don't use grouping, set the _id to null to prepare the pipeline for
-                // other aggregation functions.
-                $group['_id'] = null;
+
+                // Do the same for other columns that are selected.
+                foreach ($this->columns as $column)
+                {
+                    $key = str_replace('.', '_', $column);
+
+                    $group[$key] = array('$last' => '$' . $column);
+                }
             }
 
             // Add aggregation functions to the $group part of the aggregation pipeline,
@@ -184,22 +193,26 @@ public function getFresh($columns = array())
                 }
             }
 
-            // If no aggregation functions are used, we add the additional select columns
-            // to the pipeline here, aggregating them by $last.
-            else
+            // When using pagination, we limit the number of returned columns
+            // by adding a projection.
+            if ($this->paginating)
             {
                 foreach ($this->columns as $column)
                 {
-                    $key = str_replace('.', '_', $column);
-
-                    $group[$key] = array('$last' => '$' . $column);
+                    $this->projections[$column] = 1;
                 }
             }
 
+            // The _id field is mandatory when using grouping.
+            if ($group and empty($group['_id']))
+            {
+                $group['_id'] = null;
+            }
+
             // Build the aggregation pipeline.
             $pipeline = array();
             if ($wheres) $pipeline[] = array('$match' => $wheres);
-            $pipeline[] = array('$group' => $group);
+            if ($group)  $pipeline[] = array('$group' => $group);
 
             // Apply order and limit
             if ($this->orders)      $pipeline[] = array('$sort' => $this->orders);
@@ -370,6 +383,20 @@ public function whereBetween($column, array $values, $boolean = 'and', $not = fa
         return $this;
     }
 
+    /**
+     * Set the limit and offset for a given page.
+     *
+     * @param  int  $page
+     * @param  int  $perPage
+     * @return \Illuminate\Database\Query\Builder|static
+     */
+    public function forPage($page, $perPage = 15)
+    {
+        $this->paginating = true;
+
+        return $this->skip(($page - 1) * $perPage)->take($perPage);
+    }
+
     /**
      * Insert a new record into the database.
      *

tests/QueryTest.php

@@ -7,10 +7,6 @@ class QueryTest extends TestCase {
 	public function setUp()
 	{
 		parent::setUp();
-
-		// only run this stuff once
-		if (self::$started) return;
-
 		User::create(array('name' => 'John Doe', 'age' => 35, 'title' => 'admin'));
 		User::create(array('name' => 'Jane Doe', 'age' => 33, 'title' => 'admin'));
 		User::create(array('name' => 'Harry Hoe', 'age' => 13, 'title' => 'user'));
@@ -20,8 +16,12 @@ public function setUp()
 		User::create(array('name' => 'Tommy Toe', 'age' => 33, 'title' => 'user'));
 		User::create(array('name' => 'Yvonne Yoe', 'age' => 35, 'title' => 'admin'));
 		User::create(array('name' => 'Error', 'age' => null, 'title' => null));
+	}
 
-		self::$started = true;
+	public function tearDown()
+	{
+		User::truncate();
+		parent::tearDown();
 	}
 
 	public function testWhere()
@@ -311,16 +311,7 @@ public function testPaginate()
 		$this->assertEquals(2, $results->count());
 		$this->assertNull($results->first()->title);
 		$this->assertEquals(9, $results->total());
-	}
-
-	/*
-	 * FIXME: This should be done in tearDownAfterClass, but something doens't work:
-	 *        https://travis-ci.org/duxet/laravel-mongodb/jobs/46657530
-	 */
-	public function testTruncate()
-	{
-		User::truncate();
-		$this->assertEquals(0, User::count());
+		$this->assertEquals(1, $results->currentPage());
 	}
 
 }

tests/TestCase.php

@@ -27,13 +27,9 @@ protected function getEnvironmentSetUp($app)
         // reset base path to point to our package's src directory
         //$app['path.base'] = __DIR__ . '/../src';
 
-        // load custom config
         $config = require 'config/database.php';
 
-        // set mongodb as default connection
         $app['config']->set('database.default', 'mongodb');
-
-        // overwrite database configuration
         $app['config']->set('database.connections.mysql', $config['connections']['mysql']);
         $app['config']->set('database.connections.mongodb', $config['connections']['mongodb']);