diff --git a/README.md b/README.md
index 18b5a0b..d6985bb 100644
--- a/README.md
+++ b/README.md
@@ -41,7 +41,7 @@ class Note extends ODM\Document\Document
 }
 
 /* Initialize connection */
-$dbal = new ODM\DBAL('127.0.0.1', '27017', 'test2');
+$dbal = new ODM\DBAL('127.0.0.1', '27017', 'test');
 $factory = new ODM\DocumentMapper\DataMapperFactory($dbal);
 
 /* Initialize DataMapper for your Document */
diff --git a/composer.json b/composer.json
index 83f091a..aad52ca 100644
--- a/composer.json
+++ b/composer.json
@@ -3,7 +3,8 @@
     "description": "mongo odm",
     "type": "library",
     "require": {
-        "mongodb/mongodb": "^1.1"
+        "mongodb/mongodb": "^1.1",
+        "php": "7.*"
     },
     "autoload": {
         "psr-4": { "ODM\\": "src/" }
diff --git a/src/DBAL.php b/src/DBAL.php
index b5d547f..aef52d8 100644
--- a/src/DBAL.php
+++ b/src/DBAL.php
@@ -8,79 +8,85 @@ class DBAL
 {
     private $db;
 
-    public function __construct($host, $port, $db_name)
+    /**
+     * DBAL constructor.
+     * @param string $host
+     * @param string $port
+     * @param string $db_name
+     */
+    public function __construct(string $host, string $port, string $db_name)
     {
         $this->db = (new Client("mongodb://$host:$port"))->$db_name;
     }
 
     /**
-     * @param       $table_name
-     * @param array $data
-     * @return mixed
+     * @param string $table_name
+     * @param array  $data
+     * @return \MongoDB\InsertOneResult
      */
-    public function insert($table_name, array $data)
+    public function insert(string $table_name, array $data)
     {
         return $this->db->$table_name->insertOne($data);
     }
 
     /**
-     * @param       $table_name
-     * @param array $data
-     * @return mixed
+     * @param string $table_name
+     * @param array  $data
+     * @return \MongoDB\InsertManyResult
      */
-    public function insertMany($table_name, array $data)
+    public function insertMany(string $table_name, array $data)
     {
         return $this->db->$table_name->insertMany($data);
     }
 
     /**
-     * @param       $table_name
-     * @param array $filter
-     * @param array $data
-     * @return mixed
+     * @param string $table_name
+     * @param array  $filter
+     * @param array  $data
+     * @return \MongoDB\UpdateResult
      */
-    public function update($table_name, array $filter, array $data)
+    public function update(string $table_name, array $filter, array $data)
     {
         return $this->db->$table_name->updateOne($filter, ['$set' => $data]);
     }
 
     /**
-     * @param       $table_name
-     * @param array $filter
-     * @return mixed
+     * @param string $table_name
+     * @param array  $filter
+     * @return \MongoDB\DeleteResult
      */
-    public function delete($table_name, array $filter)
+    public function delete(string $table_name, array $filter)
     {
         return $this->db->$table_name->deleteOne($filter);
     }
 
     /**
-     * @param       $table_name
-     * @param array $filter
-     * @param array $options
-     * @return mixed
+     * @param string $table_name
+     * @param array  $filter
+     * @param array  $options
+     * @return \MongoDB\Driver\Cursor
      */
-    public function find($table_name, array $filter, array $options = [])
+    public function find(string $table_name, array $filter, array $options = [])
     {
         return $this->db->$table_name->find($filter, $options);
     }
 
     /**
-     * @param       $table_name
-     * @param array $filter
-     * @param array $options
-     * @return mixed
+     * @param string $table_name
+     * @param array  $filter
+     * @param array  $options
+     * @return array|null|object
      */
-    public function findOne($table_name, array $filter, array $options = [])
+    public function findOne(string $table_name, array $filter, array $options = [])
     {
         return $this->db->$table_name->findOne($filter, $options);
     }
 
     /**
-     * @param $table_name
-     * @return mixed
+     * @param string $table_name
+     * @return array|object
      */
-    public function drop($table_name)
+    public function drop(string $table_name)
     {
         return $this->db->$table_name->drop();
     }
diff --git a/src/Document/Document.php b/src/Document/Document.php
index 6082ae2..418a681 100644
--- a/src/Document/Document.php
+++ b/src/Document/Document.php
@@ -4,25 +4,24 @@
 
 class Document
 {
-   private $id;
+    private $id;
 
     /**
      * @return mixed
      */
     public function getId()
     {
-        return $this->id;
+        return (string)$this->id;
     }
 
     /**
      * @param $id
      * @return $this
      */
-    public function setId($id)
+    public function setId(string $id)
     {
         $this->id = $id;
 
         return $this;
     }
-
 }
\ No newline at end of file
diff --git a/src/DocumentMapper/DataMapper.php b/src/DocumentMapper/DataMapper.php
index a5fc4b5..6a2605f 100644
--- a/src/DocumentMapper/DataMapper.php
+++ b/src/DocumentMapper/DataMapper.php
@@ -4,40 +4,43 @@
 
 use ODM\DBAL;
 use ODM\Document\Document;
+use ODM\Instantiator\Instantiator;
 
 class DataMapper
 {
     private $dbal;
 
     private $table_name;
-    private $class;
+    private $class_name;
+    private $instantiator;
 
     const MONGO_ID = '_id';
     const ID       = 'id';
 
     /**
      * DataMapper constructor.
-     * @param DBAL $dbal
-     * @param      $class
+     * @param DBAL   $dbal
+     * @param string $class_name
      */
-    public function __construct(DBAL $dbal, $class)
+    public function __construct(DBAL $dbal, string $class_name)
     {
-        $this->dbal       = $dbal;
-        $this->class      = $class;
-        $path             = explode('\\', $class);
-        $this->table_name = mb_strtolower($this->camelCaseToSnake(array_pop($path)));
+        $this->dbal         = $dbal;
+        $this->class_name   = $class_name;
+        $path               = explode('\\', $class_name);
+        $this->table_name   = mb_strtolower($this->camelCaseToSnake(array_pop($path)));
+        $this->instantiator = new Instantiator();
     }
 
     /**
      * @param Document $obj
-     * @return mixed
+     * @return Document
      */
     public function insert(Document $obj)
     {
         $data = $this->objToArray($obj);
 
         if (array_key_exists(self::MONGO_ID, $data) && empty($data[self::MONGO_ID])) {
-            unset($data[self::MONGO_ID]);
+            $data[self::MONGO_ID] = $this->generateId();
         }
 
         $result = $this->dbal->insert($this->table_name, $data);
@@ -61,7 +64,7 @@ public function update(Document $obj)
 
     /**
      * @param Document $obj
-     * @return mixed
+     * @return \MongoDB\DeleteResult
      */
     public function delete(Document $obj)
     {
@@ -69,11 +72,11 @@ public function delete(Document $obj)
     }
 
     /**
-     * @return mixed
+     * @return bool
      */
     public function drop()
     {
-        return $this->dbal->drop($this->table_name);
+        return (bool)$this->dbal->drop($this->table_name);
     }
 
     /**
@@ -90,7 +93,7 @@ public function find(array $filter = [], array $options = [])
 
         $result = [];
         foreach ($this->dbal->find($this->table_name, $filter, $options) as $r) {
-            $result[] = $this->mapObj(new $this->class, $r);
+            $result[] = $this->mapObj($this->class_name, (array)$r);
         }
 
         return $result;
@@ -110,35 +113,51 @@ public function findOne(array $filter = [], array $options = [])
 
         $data = $this->dbal->findOne($this->table_name, $filter, $options);
 
-        return empty($data) ? null : $this->mapObj(new $this->class, $data);
+        return empty($data) ? null : $this->mapObj($this->class_name, (array)$data);
     }
 
     /**
-     * @param $obj
-     * @param $data
-     * @return mixed
+     * @return string
      */
-    private function mapObj($obj, $data)
+    private function generateId()
     {
-        $methods = get_class_methods(get_class($obj));
+        return bin2hex(random_bytes(15));
+    }
 
-        foreach ((array)$data as $field => $value) {
+    /**
+     * @param string $class_name
+     * @param array  $data
+     * @return Document
+     */
+    private function mapObj(string $class_name, array $data)
+    {
+        $obj     = $this->instantiator->instantiate($class_name);
+        $reflect = new \ReflectionClass($obj);
+        $properties = array_merge($reflect->getProperties(), $reflect->getParentClass()->getProperties());
 
-            $field_name = self::MONGO_ID === (string)$field ? self::ID : $field;
-            $value      = self::MONGO_ID === (string)$field ? (string)$value : $value;
-            $value      = is_object($value) ? (array)$value : $value;
+        foreach($properties  as $prop) {
 
-            if (null === $value) {
+            if ($prop->getName() === self::ID) {
+                $prop_name = self::MONGO_ID;
+            } else {
+                $prop_name = $prop->getName();
+            }
+
+            if (!array_key_exists($prop_name, $data)) {
                 continue;
             }
 
-            $setter = 'set' . $this->snakeToCamelCase($field_name);
+            if ($prop->isPrivate() || $prop->isProtected()) {
+                $prop->setAccessible(true);
+            }
+
+            if ($prop->getName() === self::ID) {
+                $prop->setValue($obj, (string)$data[$prop_name]);
 
-            if (!in_array($setter, $methods, true)) {
                 continue;
             }
 
-            $obj->$setter($value);
+            $prop->setValue($obj, $data[$prop_name]);
         }
 
         return $obj;
@@ -148,21 +167,7 @@ private function mapObj($obj, $data)
      * @param $input
      * @return string
      */
-    private function snakeToCamelCase($input)
-    {
-        $new = [];
-        foreach (explode('_', $input) as $key => $word) {
-            $new[] = ucfirst($word);
-        }
-
-        return implode('', $new);
-    }
-
-    /**
-     * @param $input
-     * @return string
-     */
-    private function camelCaseToSnake($input)
+    private function camelCaseToSnake(string $input)
     {
         preg_match_all('!([A-Z][A-Z0-9]*(?=$|[A-Z][a-z0-9])|[A-Za-z][a-z0-9]+)!', $input, $matches);
         $res = $matches[0];
@@ -174,15 +179,16 @@ private function camelCaseToSnake($input)
     }
 
     /**
-     * @param $obj
+     * @param Document $obj
      * @return array
      */
-    public function objToArray($obj)
+    private function objToArray(Document $obj)
     {
         $data    = [];
         $reflect = new \ReflectionClass($obj);
-        foreach ($reflect->getProperties() as $prop) {
-            $getter = 'get' . $this->snakeToCamelCase($prop->getName());
+        $properties = array_merge($reflect->getProperties(), $reflect->getParentClass()->getProperties());
+
+        foreach ($properties as $prop) {
 
             if ($prop->getName() === self::ID) {
                 $prop_name = self::MONGO_ID;
@@ -190,7 +196,11 @@ public function objToArray($obj)
                 $prop_name = $prop->getName();
             }
 
-            $data[$prop_name] = $obj->$getter();
+            if ($prop->isPrivate() || $prop->isProtected()) {
+                $prop->setAccessible(true);
+            }
+
+            $data[$prop_name] = $prop->getValue($obj);
         }
 
         return $data;
diff --git a/src/DocumentMapper/DataMapperFactory.php b/src/DocumentMapper/DataMapperFactory.php
index db8ebdf..5113db5 100644
--- a/src/DocumentMapper/DataMapperFactory.php
+++ b/src/DocumentMapper/DataMapperFactory.php
@@ -18,11 +18,11 @@ public function __construct(DBAL $dbal)
     }
 
     /**
-     * @param $class
+     * @param $class_name
      * @return DataMapper
      */
-    public function init($class)
+    public function init($class_name)
     {
-        return new DataMapper($this->dbal, $class);
+        return new DataMapper($this->dbal, $class_name);
     }
 }
\ No newline at end of file
diff --git a/src/Instantiator/Instantiator.php b/src/Instantiator/Instantiator.php
new file mode 100644
index 0000000..873aee8
--- /dev/null
+++ b/src/Instantiator/Instantiator.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace ODM\Instantiator;
+
+class Instantiator
+{
+    /**
+     * @param string $class_name
+     * @return mixed
+     */
+    public function instantiate(string $class_name)
+    {
+        $serialized_string = sprintf(
+            'O:%d:"%s":0:{}',
+            strlen($class_name),
+            $class_name
+        );
+
+        return unserialize($serialized_string);
+    }
+}
\ No newline at end of file