added DATE_DESC and DATE_ASC sorting operator

Author: Mauro Cassani

README.md

@@ -110,6 +110,8 @@ foreach ($qb->getResults() as $element){
 
 * `ASC` (default operator, can be omitted)
 * `DESC`
+* `DATE_ASC`
+* `DATE_DESC`
 
 ## Performing Queries
 
@@ -132,7 +134,7 @@ foreach ($qb->getResults() as $element){
 
 ## Working with dates
 
-You can perform queries based on datetime fields. You must specify **date format** if your format is not `YYYY-mm-dd`:
+You can perform queries based on datetime fields. You can use `DATE_ASC` or `DATE_DESC` operator to sort results by date. You must specify **date format** if your format is not `YYYY-mm-dd`:
 
 ```php
 use ArrayQuery\QueryBuilder;
@@ -141,7 +143,7 @@ $qb = QueryBuilder::create($array);
 $qb
     ->addCriterion('registration_date', '01/05/2017', 'GT_DATE', 'd/m/Y')
     ->addCriterion('rate', '3', '>')
-    ->sortedBy('title')
+    ->sortedBy('registration_date', `DATE_DESC`, 'd/m/Y')
     ->limit(0, 10);
 
 foreach ($qb->getResults() as $element){

src/Filters/SortingFilter.php

@@ -18,6 +18,8 @@ class SortingFilter extends AbstractFilter
     public static $operatorsMap = [
         'ASC',
         'DESC',
+        'DATE_ASC',
+        'DATE_DESC',
     ];
 
     /**
@@ -45,14 +47,19 @@ private static function sort($results, $sortingArray)
             $valueA = self::getArrayElementValueFromKey($sortingArray['key'], $first);
             $valueB = self::getArrayElementValueFromKey($sortingArray['key'], $second);
 
-            if ($valueA === $valueB) {
+            if(isset($sortingArray['format'])){
+                $valueA = \DateTimeImmutable::createFromFormat(($sortingArray['format']) ?: 'Y-m-d', $valueA);
+                $valueB = \DateTimeImmutable::createFromFormat(($sortingArray['format']) ?: 'Y-m-d', $valueB);
+            }
+
+            if ($valueA == $valueB) {
                 return 0;
             }
 
             return ($valueA < $valueB) ? -1 : 1;
         });
 
-        if ($sortingArray['order'] === 'DESC') {
+        if ($sortingArray['order'] === 'DESC' || $sortingArray['order'] === 'DATE_DESC') {
             return array_reverse($results);
         }
 

src/QueryBuilder.php

@@ -115,7 +115,7 @@ private function isAValidCriterionOperator($operator)
      *
      * @throws NotValidSortingOperatorException
      */
-    public function sortedBy($key, $operator = 'ASC')
+    public function sortedBy($key, $operator = 'ASC', $format = null)
     {
         if (!$this->isAValidSortingOperator($operator)) {
             throw new NotValidSortingOperatorException($operator.' is not a valid sorting operator.');
@@ -124,6 +124,7 @@ public function sortedBy($key, $operator = 'ASC')
         $this->sortedBy = [
             'key' => $key,
             'order' => $operator,
+            'format' => $format
         ];
 
         return $this;

tests/QueryBuilderTest.php

@@ -435,4 +435,40 @@ public function it_should_get_results_from_a_query_with_equals_date()
             $this->assertEquals('Chelsey Dietrich', $results[0]['name']);
         }
     }
+
+    /**
+     * @test
+     */
+    public function it_should_get_results_from_a_query_with_equals_date_sorted_by_date_asc()
+    {
+        foreach ($this->usersArrays as $array) {
+            $qb = QueryBuilder::create($array)
+                ->addCriterion('registration_date', '01/05/2017', 'LTE_DATE', 'd/m/Y')
+                ->sortedBy('registration_date', 'DATE_ASC', 'd/m/Y');
+
+            $results = $qb->getResults();
+
+            $this->assertEquals(4, $qb->getCount());
+            $this->assertEquals(10, $results[0]['id']);
+            $this->assertEquals('Clementina DuBuque', $results[0]['name']);
+        }
+    }
+
+    /**
+     * @test
+     */
+    public function it_should_get_results_from_a_query_with_equals_date_sorted_by_date_desc()
+    {
+        foreach ($this->usersArrays as $array) {
+            $qb = QueryBuilder::create($array)
+                ->addCriterion('registration_date', '01/05/2017', 'LTE_DATE', 'd/m/Y')
+                ->sortedBy('registration_date', 'DATE_DESC', 'd/m/Y');
+
+            $results = $qb->getResults();
+
+            $this->assertEquals(4, $qb->getCount());
+            $this->assertEquals(3, $results[0]['id']);
+            $this->assertEquals('Clementine Bauch', $results[0]['name']);
+        }
+    }
 }