Add refresh

Closes #139

README.md

@@ -25,6 +25,7 @@ Supports all key types - primary hash key and composite keys.
   * [limit() and take()](#limit-and-take)
   * [firstOrFail()](#firstorfail)
   * [findOrFail()](#findorfail)
+  * [refresh()](#refresh)
   * [Query scope](#query-scope)
   * [REMOVE — Deleting Attributes From An Item](#remove--deleting-attributes-from-an-item)
   * [toSql() Style](#tosql-style)
@@ -231,6 +232,13 @@ $model->findOrFail('foo');
 $model->findOrFail(['id' => 'foo', 'id2' => 'bar']);
 ```
 
+#### refresh()
+
+```php
+$model = Model::first();
+$model->refresh();
+```
+
 #### Query Scope
 
 ```php

src/DynamoDbModel.php

@@ -192,6 +192,21 @@ public static function all($columns = [])
         return $instance->newQuery()->get($columns);
     }
 
+    public function refresh()
+    {
+        if (! $this->exists) {
+            return $this;
+        }
+
+        $query = $this->newQuery();
+
+        $refreshed = $query->find($this->getKeys());
+
+        $this->setRawAttributes($refreshed->toArray());
+
+        return $this;
+    }
+
     /**
      * @return DynamoDbQueryBuilder
      */

tests/DynamoDbCompositeModelTest.php

@@ -534,6 +534,26 @@ public function testUsingBothKeyAndFilterConditionsForModelWithIndex()
         );
     }
 
+    public function testRefresh()
+    {
+        $this->seed();
+
+        $model = $this->testModel->first();
+
+        $originalHash = $model->id;
+        $originalRange = $model->id2;
+        $originalName = $model->name;
+
+        $model->name = 'Modified Name';
+
+        $refreshed = $model->refresh();
+
+        $this->assertEquals($originalName, $model->name);
+        $this->assertEquals($originalHash, $model->id);
+        $this->assertEquals($originalRange, $model->id2);
+        $this->assertEquals($refreshed, $model);
+    }
+
     public function seed($attributes = [], $exclude = [])
     {
         $item = [

tests/DynamoDbModelTest.php

@@ -821,6 +821,24 @@ public function testUsingBothKeyAndFilterConditionsForModelWithIndex()
         $this->assertUsingKeyAndFilterConditions(new PrimaryKeyWithIndexModel());
     }
 
+    public function testRefresh()
+    {
+        $this->seed();
+
+        $model = $this->testModel->first();
+
+        $originalId = $model->id;
+        $originalName = $model->name;
+
+        $model->name = 'Modified Name';
+
+        $refreshed = $model->refresh();
+
+        $this->assertEquals($originalName, $model->name);
+        $this->assertEquals($originalName, $model->name);
+        $this->assertEquals($refreshed, $model);
+    }
+
     protected function assertRemoveAttributes($item)
     {
         $this->assertNull($item->name);