added increment and decrement methods

Author: mehedimi

src/Kitar/Dynamodb/Model/Model.php

@@ -326,6 +326,8 @@ public function __call($method, $parameters)
             "keyCondition",
             "keyConditionIn",
             "keyConditionBetween",
+            'increment',
+            'decrement'
         ];
 
         if (! in_array($method, $allowedBuilderMethods)) {

src/Kitar/Dynamodb/Query/Builder.php

@@ -295,6 +295,40 @@ public function updateItem($item)
         return $this->process('updateItem', null);
     }
 
+    /**
+     * @inheritdoc
+     */
+    public function increment($column, $amount = 1, array $extra = [])
+    {
+        return $this->incrementOrDecrement($column, '+', $amount, $extra);
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function decrement($column, $amount = 1, array $extra = [])
+    {
+        return $this->incrementOrDecrement($column, '-', $amount, $extra);
+    }
+
+    /**
+     * Increment or decrement column's value by a given amount.
+     *
+     * @param $column
+     * @param $symbol
+     * @param int $amount
+     * @param array $extra
+     * @return array|\Aws\Result|Aws\Result|Illuminate\Support\Collection
+     */
+    protected function incrementOrDecrement($column, $symbol, $amount = 1, array $extra = [])
+    {
+        $name = $this->expression_attributes->addName($column);
+        $value = $this->expression_attributes->addValue($amount);
+        $this->updates['set'][] = "{$name} = {$name} {$symbol} {$value}";
+
+        return $this->updateItem($extra);
+    }
+
     /**
      * Query.
      *

tests/Query/BuilderTest.php

@@ -700,6 +700,90 @@ public function it_can_process_update_item()
         $this->assertNull($query['processor']);
     }
 
+    /** @test */
+    public function it_can_increment_value_of_attribute()
+    {
+        $method = 'updateItem';
+        $params = [
+            'TableName' => 'Thread',
+            'Key' => [
+                'ForumName' => [
+                    'S' => 'Laravel'
+                ],
+                'Subject' => [
+                    'S' => 'Laravel Thread 1'
+                ]
+            ],
+            'UpdateExpression' => 'set #1 = #1 + :1, #2 = :2',
+            'ExpressionAttributeNames' => [
+                '#1' => 'Replies',
+                '#2' => 'LastPostedBy'
+            ],
+            'ExpressionAttributeValues' => [
+                ':1' => [
+                    'N' => '2'
+                ],
+                ':2' => [
+                    'S' => 'User A'
+                ]
+            ]
+        ];
+
+        $query = $this->newQuery('Thread')
+            ->key([
+                'ForumName' => 'Laravel',
+                'Subject' => 'Laravel Thread 1'
+            ])->increment('Replies', 2, [
+                'LastPostedBy' => 'User A'
+            ]);
+
+        $this->assertEquals($method, $query['method']);
+        $this->assertEquals($params, $query['params']);
+        $this->assertNull($query['processor']);
+    }
+
+    /** @test */
+    public function it_can_decrement_value_of_attribute()
+    {
+        $method = 'updateItem';
+        $params = [
+            'TableName' => 'Thread',
+            'Key' => [
+                'ForumName' => [
+                    'S' => 'Laravel'
+                ],
+                'Subject' => [
+                    'S' => 'Laravel Thread 1'
+                ]
+            ],
+            'UpdateExpression' => 'set #1 = #1 - :1, #2 = :2',
+            'ExpressionAttributeNames' => [
+                '#1' => 'Replies',
+                '#2' => 'LastPostedBy'
+            ],
+            'ExpressionAttributeValues' => [
+                ':1' => [
+                    'N' => '2'
+                ],
+                ':2' => [
+                    'S' => 'User A'
+                ]
+            ]
+        ];
+
+        $query = $this->newQuery('Thread')
+            ->key([
+                'ForumName' => 'Laravel',
+                'Subject' => 'Laravel Thread 1'
+            ])->decrement('Replies', 2, [
+                'LastPostedBy' => 'User A'
+            ]);
+
+        $this->assertEquals($method, $query['method']);
+        $this->assertEquals($params, $query['params']);
+        $this->assertNull($query['processor']);
+    }
+
     /** @test */
     public function it_can_set_single_attribute()
     {