Support ScanIndexForward option

Author: kitar

README.md

@@ -38,6 +38,7 @@ A DynamoDB based Eloquent model and Query builder for Laravel.
   * [Working with Queries](#working-with-queries)
     + [query() and keyCondition()](#query-and-keycondition)
     + [keyConditionBetween()](#keyconditionbetween)
+    + [Sort order](#sort-order)
   * [Working with Scans](#working-with-scans)
     + [scan()](#scan)
   * [Filtering the Results](#filtering-the-results)
@@ -559,6 +560,17 @@ $response = DB::table('Thread')
                 ->query();
 ```
 
+#### Sort order
+
+`query` results are always sorted by the sort key value. To reverse the order, set the `ScanIndexForward` parameter to `false`.
+
+```php
+$response = DB::table('Thread')
+                ->keyCondition('ForumName', '=', 'Amazon DynamoDB')
+                ->scanIndexForward(false)
+                ->query();
+```
+
 ### Working with Scans
 
 #### scan()

src/Kitar/Dynamodb/Query/Builder.php

@@ -42,6 +42,11 @@ class Builder extends BaseBuilder
         'remove' => []
     ];
 
+    /**
+     * ScanIndexForward option.
+     */
+    public $scan_index_forward;
+
     /**
      * LastEvaluatedKey option.
      * @var array|null
@@ -153,6 +158,19 @@ public function key(array $key)
         return $this;
     }
 
+    /**
+     * Set the ScanIndexForward option.
+     *
+     * @param bool $bool
+     * @return $this
+     */
+    public function scanIndexForward($bool)
+    {
+        $this->scan_index_forward = $bool;
+
+        return $this;
+    }
+
     /**
      * Set the ExclusiveStartKey option.
      *
@@ -523,6 +541,7 @@ protected function process($query_method, $processor_method)
             $this->grammar->compileItem($this->item),
             $this->grammar->compileUpdates($this->updates),
             $this->grammar->compileDynamodbLimit($this->limit),
+            $this->grammar->compileScanIndexForward($this->scan_index_forward),
             $this->grammar->compileExclusiveStartKey($this->exclusive_start_key),
             $this->grammar->compileConsistentRead($this->consistent_read),
             $this->grammar->compileExpressionAttributes($this->expression_attributes)

src/Kitar/Dynamodb/Query/Grammar.php

@@ -152,6 +152,17 @@ public function compileDynamodbLimit($limit)
         ];
     }
 
+    public function compileScanIndexForward($bool)
+    {
+        if (is_null($bool)) {
+            return [];
+        }
+
+        return [
+            'ScanIndexForward' => $bool
+        ];
+    }
+
     public function compileExclusiveStartKey($key)
     {
         if (empty($key)) {

tests/Query/BuilderTest.php

@@ -108,6 +108,25 @@ public function it_can_set_limit()
         $this->assertEquals($params, $query['params']);
     }
 
+    /** @test */
+    public function it_can_set_scan_index_forward()
+    {
+        $params = [
+            'TableName' => 'ProductCatalog',
+            'ScanIndexForward' => false,
+            'Key' => [
+                'Id' => [
+                    'N' => '101'
+                ]
+            ]
+        ];
+        $query = $this->newQuery('ProductCatalog')
+                      ->scanIndexForward(false)
+                      ->getItem(['Id'=> 101]);
+
+        $this->assertEquals($params, $query['params']);
+    }
+
     /** @test */
     public function it_can_set_exclusive_start_key()
     {