diff --git a/.gitignore b/.gitignore
index 604515e..2901232 100644
--- a/.gitignore
+++ b/.gitignore
@@ -29,4 +29,7 @@ data
 .mr.developer.cfg
 
 #PyCharm
-.idea/
\ No newline at end of file
+.idea/
+
+#Sublime
+*.sublime-*
diff --git a/README.md b/README.md
index 68a92ee..b499fe4 100644
--- a/README.md
+++ b/README.md
@@ -20,7 +20,7 @@ The next steps are provide support to:
 * authentication
 * nearest preference in replica sets
 * gridfs
-* all python versions (2.5, 2.6, 2.7, 3.2 and PyPy), only python 2.7 is tested now
+* all python versions (2.6, 2.7, 3.2 and PyPy), only python 2.7 is tested now
 
 ## Documentation
 
@@ -67,7 +67,7 @@ class Handler(tornado.web.RequestHandler):
     def get(self):
         user = {'_id': ObjectId(), 'name': 'User Name'}
         yield gen.Task(self.db.user.insert, user)
-        
+
         yield gen.Task(self.db.user.update, user['_id'], {"$set": {'name': 'New User Name'}})
 
         user_found = yield gen.Task(self.db.user.find_one, user['_id'])
@@ -98,10 +98,10 @@ class Handler(tornado.web.RequestHandler):
     @gen.engine
     def get(self):
         user = {'_id': ObjectId()}
-        
+
         # write on primary
         yield gen.Task(self.db.user.insert, user)
-        
+
         # wait for replication
         time.sleep(2)
 
@@ -191,4 +191,4 @@ make test
 
 ## Issues
 
-Please report any issues via [github issues](https://github.com/marcelnicolay/mongotor/issues)
\ No newline at end of file
+Please report any issues via [github issues](https://github.com/marcelnicolay/mongotor/issues)
diff --git a/docs/source/installation.rst b/docs/source/installation.rst
index 0b2ea45..9f3f7a6 100644
--- a/docs/source/installation.rst
+++ b/docs/source/installation.rst
@@ -12,7 +12,7 @@ MongoTor supports installation using standard Python "distutils" or
 Install via easy_install or pip
 -------------------------------
 
-When ``easy_install`` or ``pip`` is available, the distribution can be 
+When ``easy_install`` or ``pip`` is available, the distribution can be
 downloaded from Pypi and installed in one step::
 
     easy_install mongotor
@@ -39,12 +39,14 @@ Python prompt like this:
 
 .. sourcecode:: python
 
-     >>> import mongotor 
+     >>> import mongotor
      >>> mongotor.version # doctest: +SKIP
 
 Requirements
 ------------
 
+Python version 2.6+ is required. But only version 2.7 is tested for now.
+
 The following three python libraries are required.
 
   * `pymongo <http://github.com/mongodb/mongo-python-driver>`_ version 1.9+ for bson library
@@ -52,4 +54,4 @@ The following three python libraries are required.
 
 .. note::
    The above requirements are automatically managed when installed using
-   any of the supported installation methods
\ No newline at end of file
+   any of the supported installation methods
diff --git a/mongotor/__init__.py b/mongotor/__init__.py
index bb8a479..ec9f7d0 100644
--- a/mongotor/__init__.py
+++ b/mongotor/__init__.py
@@ -15,4 +15,4 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-version = "0.1.0"
+version = "0.1.5"
diff --git a/mongotor/cursor.py b/mongotor/cursor.py
index 5b43252..17eebb8 100644
--- a/mongotor/cursor.py
+++ b/mongotor/cursor.py
@@ -95,8 +95,8 @@ def find(self, callback=None):
         else:
             callback((response['data'], None))
 
-    @gen.engine
-    def count(self, callback):
+    @gen.coroutine
+    def count(self):
         """Get the size of the results set for this query.
 
         Returns the number of documents in the results set for this query. Does
@@ -110,10 +110,10 @@ def count(self, callback):
         if response and len(response) > 0 and 'n' in response:
             total = int(response['n'])
 
-        callback(total)
+        raise gen.Return(total)
 
-    @gen.engine
-    def distinct(self, key, callback):
+    @gen.coroutine
+    def distinct(self, key):
         """Get a list of distinct values for `key` among all documents
         in the result set of this query.
 
@@ -131,7 +131,7 @@ def distinct(self, key, callback):
         response, error = yield gen.Task(self._database.command,
             'distinct', self._collection, **command)
 
-        callback(response['values'])
+        raise gen.Return(response['values'])
 
     def _query_options(self):
         """Get the query options string to use for this query."""
diff --git a/mongotor/database.py b/mongotor/database.py
index b28ea75..79f5579 100644
--- a/mongotor/database.py
+++ b/mongotor/database.py
@@ -29,7 +29,7 @@
 def initialized(fn):
     @wraps(fn)
     def wrapped(self, *args, **kwargs):
-        if not hasattr(self, '_initialized'):
+        if not hasattr(self, '_initialized') or not self._initialized:
             raise DatabaseError("you must be initialize database before perform this action")
 
         return fn(self, *args, **kwargs)
@@ -45,6 +45,7 @@ class Database(object):
     def __new__(cls):
         if not cls._instance:
             cls._instance = super(Database, cls).__new__(cls)
+            cls._initialized = False
 
         return cls._instance
 
@@ -147,7 +148,8 @@ def disconnect(cls):
         >>> Database.disconnect()
 
         """
-        if not cls._instance or not hasattr(cls._instance, '_initialized'):
+        if (not cls._instance or not hasattr(cls._instance, '_initialized')
+                or not cls._instance._initialized):
             raise ValueError("Database isn't initialized")
 
         for node in cls._instance._nodes:
diff --git a/mongotor/message.py b/mongotor/message.py
index 6cd3226..c857dbf 100644
--- a/mongotor/message.py
+++ b/mongotor/message.py
@@ -28,7 +28,7 @@
 from mongotor.errors import InvalidOperationError
 
 
-__ZERO = "\x00\x00\x00\x00"
+__ZERO = b"\x00\x00\x00\x00"
 
 
 def __last_error(args):
@@ -57,7 +57,7 @@ def insert(collection_name, docs, check_keys, safe, last_error_args):
     """
     data = __ZERO
     data += bson._make_c_string(collection_name)
-    bson_data = "".join([bson.BSON.encode(doc, check_keys) for doc in docs])
+    bson_data = b"".join([bson.BSON.encode(doc, check_keys) for doc in docs])
     if not bson_data:
         raise InvalidOperationError("cannot do an empty bulk insert")
     data += bson_data
diff --git a/mongotor/orm/collection.py b/mongotor/orm/collection.py
index 985125a..9292782 100644
--- a/mongotor/orm/collection.py
+++ b/mongotor/orm/collection.py
@@ -15,6 +15,7 @@
 # You should have received a copy of the GNU Lesser General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import re
 import logging
 from tornado import gen
 from mongotor.client import Client
@@ -32,6 +33,9 @@
 class CollectionMetaClass(type):
 
     def __new__(cls, name, bases, attrs):
+        if not attrs.get('__collection__'):
+            attrs['__collection__'] = re.sub(
+                r'\B([A-Z]+)', r'_\1', name).lower()
         global __lazy_classes__
 
         # Add the document's fields to the _data
@@ -65,6 +69,10 @@ class Collection(object):
     >>> class Users(collection.Collection):
     >>>     __collection__ = 'users'
     >>>     name = field.StringField()
+
+    If you do not specify `__collection__` attribute, it is
+    auto-generated from class name. Camel case is converted
+    to snake case. For example: CamelCase -> camel_case.
     """
     __metaclass__ = CollectionMetaClass
 
@@ -133,8 +141,11 @@ def create(cls, dictionary, cleaned=False):
 
         return instance
 
-    @gen.engine
-    def save(self, safe=True, check_keys=True, callback=None):
+    def get_client(self):
+        return Client(Database(), self.__collection__)
+
+    @gen.coroutine
+    def save(self, safe=True, check_keys=True):
         """Save a document
 
         >>> user = Users()
@@ -150,7 +161,7 @@ def save(self, safe=True, check_keys=True, callback=None):
         """
         pre_save.send(instance=self)
 
-        client = Client(Database(), self.__collection__)
+        client = self.get_client()
         response, error = yield gen.Task(client.insert, self.as_dict(),
             safe=safe, check_keys=check_keys)
 
@@ -158,11 +169,10 @@ def save(self, safe=True, check_keys=True, callback=None):
 
         post_save.send(instance=self)
 
-        if callback:
-            callback((response, error))
+        raise gen.Return((response, error))
 
-    @gen.engine
-    def remove(self, safe=True, callback=None):
+    @gen.coroutine
+    def remove(self, safe=True):
         """Remove a document
 
         :Parameters:
@@ -171,17 +181,15 @@ def remove(self, safe=True, callback=None):
         """
         pre_remove.send(instance=self)
 
-        client = Client(Database(), self.__collection__)
+        client = self.get_client()
         response, error = yield gen.Task(client.remove, self._id, safe=safe)
 
         post_remove.send(instance=self)
 
-        if callback:
-            callback((response, error))
+        raise gen.Return((response, error))
 
-    @gen.engine
-    def update(self, document=None, upsert=False, safe=True, multi=False,
-        callback=None, force=False):
+    @gen.coroutine
+    def update(self, document=None, upsert=False, safe=True, multi=False, force=False):
         """Update a document
 
         :Parameters:
@@ -190,8 +198,7 @@ def update(self, document=None, upsert=False, safe=True, multi=False,
         - `force`: if True will overide full document
         """
         if not document and not self.dirty_fields:
-            callback(tuple())
-            return
+            raise gen.Return(tuple())
 
         pre_update.send(instance=self)
 
@@ -201,7 +208,7 @@ def update(self, document=None, upsert=False, safe=True, multi=False,
             else:
                 document = {"$set": self.as_dict(self.dirty_fields)}
 
-        client = Client(Database(), self.__collection__)
+        client = self.get_client()
         spec = {'_id': self._id}
 
         response, error = yield gen.Task(client.update, spec, document,
@@ -211,5 +218,4 @@ def update(self, document=None, upsert=False, safe=True, multi=False,
 
         post_update.send(instance=self)
 
-        if callback:
-            callback((response, error))
+        raise gen.Return((response, error))
diff --git a/mongotor/orm/field.py b/mongotor/orm/field.py
index ff57dc4..75f3b48 100644
--- a/mongotor/orm/field.py
+++ b/mongotor/orm/field.py
@@ -67,7 +67,7 @@ def __init__(self, regex=None, *args, **kwargs):
 
     def _validate(self, value):
         value = super(StringField, self)._validate(value)
-        if self.regex is not None and self.regex.match(value) is None:
+        if value is not None and self.regex is not None and self.regex.match(value) is None:
             raise(TypeError("Value did not match regex"))
 
         return value
@@ -116,11 +116,19 @@ def __init__(self, field_type, min_value=None, max_value=None,
 
     def _validate(self, value):
         value = super(NumberField, self)._validate(value)
+        if value is None:
+            if self.min_value is not None:
+                value = self.min_value
+            elif self.max_value is not None:
+                value = self.max_value
+            else:
+                value = self.field_type()
+
         if self.min_value is not None and value < self.min_value:
             raise(TypeError("Value can not be less than %s" % (self.min_value)))
 
         if self.max_value is not None and value > self.max_value:
-            raise(TypeError("Value can not be more than %s" & (self.max_value)))
+            raise(TypeError("Value can not be more than %s" % (self.max_value)))
 
         return value
 
diff --git a/mongotor/orm/manager.py b/mongotor/orm/manager.py
index 7a76f9f..aee23b6 100644
--- a/mongotor/orm/manager.py
+++ b/mongotor/orm/manager.py
@@ -26,8 +26,8 @@ class Manager(object):
     def __init__(self, collection):
         self.collection = collection
 
-    @gen.engine
-    def find_one(self, query, callback):
+    @gen.coroutine
+    def find_one(self, query):
         client = Client(Database(), self.collection.__collection__)
         result, error = yield gen.Task(client.find_one, query)
 
@@ -35,10 +35,10 @@ def find_one(self, query, callback):
         if result:
             instance = self.collection.create(result, cleaned=True)
 
-        callback(instance)
+        raise gen.Return(instance)
 
-    @gen.engine
-    def find(self, query, callback, **kw):
+    @gen.coroutine
+    def find(self, query, **kw):
         client = Client(Database(), self.collection.__collection__)
         result, error = yield gen.Task(client.find, query, **kw)
 
@@ -48,20 +48,38 @@ def find(self, query, callback, **kw):
             for item in result:
                 items.append(self.collection.create(item, cleaned=True))
 
-        callback(items)
+        raise gen.Return(items)
 
-    def count(self, query=None, callback=None):
+    @gen.coroutine
+    def remove(self, *args, **kwargs):
         client = Client(Database(), self.collection.__collection__)
-        client.find(query).count(callback=callback)
+        result, error = yield gen.Task(client.remove, *args, **kwargs)
+        raise gen.Return(result)
 
-    @gen.engine
-    def distinct(self, key, callback, query=None):
+    @gen.coroutine
+    def all(self):
+        """Find all documents
+
+        This method is alias for `find({})`
+        """
+        result = yield self.find({})
+        raise gen.Return(result)
+
+    @gen.coroutine
+    def count(self, query=None):
+        client = Client(Database(), self.collection.__collection__)
+        count = yield client.find(query).count()
+        raise gen.Return(count)
+
+    @gen.coroutine
+    def distinct(self, key, query=None):
         client = Client(Database(), self.collection.__collection__)
-        client.find(query).distinct(key, callback=callback)
+        result = yield client.find(query).distinct(key)
+        raise gen.Return(result)
 
-    @gen.engine
+    @gen.coroutine
     def geo_near(self, near, max_distance=None, num=None, spherical=None,
-        unique_docs=None, query=None, callback=None, **kw):
+        unique_docs=None, query=None, **kw):
 
         command = SON({"geoNear": self.collection.__collection__})
 
@@ -90,10 +108,10 @@ def geo_near(self, near, max_distance=None, num=None, spherical=None,
             for item in result['results']:
                 items.append(self.collection.create(item['obj'], cleaned=True))
 
-        callback(items)
+        raise gen.Return(items)
 
-    @gen.engine
-    def map_reduce(self, map_, reduce_, callback, query=None, out=None):
+    @gen.coroutine
+    def map_reduce(self, map_, reduce_, query=None, out=None):
         command = SON({'mapreduce': self.collection.__collection__})
 
         command.update({
@@ -108,15 +126,11 @@ def map_reduce(self, map_, reduce_, callback, query=None, out=None):
 
         result, error = yield gen.Task(Database().command, command)
         if not result or int(result['ok']) != 1:
-            callback(None)
-            return
-
-        callback(result['results'])
+            raise gen.Return(None)
 
-    @gen.engine
-    def truncate(self, callback=None):
-        client = Client(Database(), self.collection.__collection__)
-        yield gen.Task(client.remove, {})
+        raise gen.Return(result['results'])
 
-        if callback:
-            callback()
+    @gen.coroutine
+    def truncate(self):
+        result = yield self.remove()
+        raise gen.Return(result)
diff --git a/setup.py b/setup.py
index a20f913..44d84ff 100644
--- a/setup.py
+++ b/setup.py
@@ -14,16 +14,16 @@ def get_packages():
     return packages
 
 setup(
-    name = 'mongotor',
-    version = version,
-    description = "(MongoDB + Tornado) is an asynchronous driver and toolkit for working with MongoDB inside a Tornado app",
-    long_description = open("README.md").read(),
-    keywords = ['mongo','tornado'],
-    author = 'Marcel Nicolay',
-    author_email = 'marcel.nicolay@gmail.com',
-    url = 'http://marcelnicolay.github.com/mongotor/',
-    license = 'OSI',
-    classifiers = ['Development Status :: 4 - Beta',
+    name='mongotor',
+    version=version,
+    description="(MongoDB + Tornado) is an asynchronous driver and toolkit for working with MongoDB inside a Tornado app",
+    long_description=open("README.md").read(),
+    keywords=['mongo', 'tornado'],
+    author='Marcel Nicolay',
+    author_email='marcel.nicolay@gmail.com',
+    url='http://marcelnicolay.github.com/mongotor/',
+    license='OSI',
+    classifiers=['Development Status :: 4 - Beta',
                    'Intended Audience :: Developers',
                    'License :: OSI Approved',
                    'Natural Language :: English',
@@ -32,7 +32,8 @@ def get_packages():
                    'Programming Language :: Python :: 2.7',
                    'Topic :: Software Development :: Libraries :: Application Frameworks',
                    ],
-    install_requires = open("requirements.txt").read().split("\n"),
-    packages = get_packages(),
-    test_suite="nose.collector"
-)
\ No newline at end of file
+    install_requires=open("requirements.txt").read().split("\n"),
+    packages=get_packages(),
+    test_suite="nose.collector",
+    use_2to3=True
+)
diff --git a/tests/orm/test_collection.py b/tests/orm/test_collection.py
index 1d875a2..99c4022 100644
--- a/tests/orm/test_collection.py
+++ b/tests/orm/test_collection.py
@@ -177,8 +177,8 @@ class CollectionTest(Collection):
             __collection__ = 'collection_test'
 
         Database.disconnect()
-        CollectionTest().save.when.called_with(callback=None) \
-            .throw(DatabaseError, 'you must be initialize database before perform this action')
+        CollectionTest().save(callback=None)
+        self.assertRaises(DatabaseError, self.wait)
 
         Database.init(["localhost:27027", "localhost:27028"], dbname='test')
 
diff --git a/tests/orm/test_manager.py b/tests/orm/test_manager.py
index 768d61f..b546542 100644
--- a/tests/orm/test_manager.py
+++ b/tests/orm/test_manager.py
@@ -88,6 +88,84 @@ def test_find_not_found(self):
 
         collections_found.should.have.length_of(0)
 
+    def test_remove_all(self):
+        """[ManagerTestCase] - Remove all documents from collection"""
+        collection_test = CollectionTest()
+        collection_test._id = ObjectId()
+        collection_test.string_attr = "string value"
+        collection_test.save(callback=self.stop)
+        self.wait()
+
+        other_collection_test = CollectionTest()
+        other_collection_test._id = ObjectId()
+        other_collection_test.string_attr = "other string value"
+        other_collection_test.save(callback=self.stop)
+        self.wait()
+
+        CollectionTest.objects.all(callback=self.stop)
+        collections_found = self.wait()
+        collections_found.should.have.length_of(2)
+
+        CollectionTest.objects.remove(callback=self.stop)
+        result = self.wait()
+
+        CollectionTest.objects.all(callback=self.stop)
+        collections_found = self.wait()
+        collections_found.should.have.length_of(0)
+
+    def test_remove_one_by_id(self):
+        """[ManagerTestCase] - Remove one document from collection by id"""
+        collection_test = CollectionTest()
+        collection_test._id = ObjectId()
+        collection_test.string_attr = "string value"
+        collection_test.save(callback=self.stop)
+        self.wait()
+
+        other_collection_test = CollectionTest()
+        other_collection_test._id = ObjectId()
+        other_collection_test.string_attr = "other string value"
+        other_collection_test.save(callback=self.stop)
+        self.wait()
+
+        CollectionTest.objects.all(callback=self.stop)
+        collections_found = self.wait()
+        collections_found.should.have.length_of(2)
+
+        CollectionTest.objects.remove(collection_test._id, callback=self.stop)
+        result = self.wait()
+
+        CollectionTest.objects.all(callback=self.stop)
+        collections_found = self.wait()
+        collections_found.should.have.length_of(1)
+        collections_found[0]._id.should.be.equal(other_collection_test._id)
+
+    def test_remove_one_by_spec(self):
+        """[ManagerTestCase] - Remove one document from collection by spec"""
+        collection_test = CollectionTest()
+        collection_test._id = ObjectId()
+        collection_test.string_attr = "string value"
+        collection_test.save(callback=self.stop)
+        self.wait()
+
+        other_collection_test = CollectionTest()
+        other_collection_test._id = ObjectId()
+        other_collection_test.string_attr = "other string value"
+        other_collection_test.save(callback=self.stop)
+        self.wait()
+
+        CollectionTest.objects.all(callback=self.stop)
+        collections_found = self.wait()
+        collections_found.should.have.length_of(2)
+
+        CollectionTest.objects.remove({"string_attr": "other string value"},
+            callback=self.stop)
+        result = self.wait()
+
+        CollectionTest.objects.all(callback=self.stop)
+        collections_found = self.wait()
+        collections_found.should.have.length_of(1)
+        collections_found[0]._id.should.be.equal(collection_test._id)
+
     def test_count(self):
         """[ManagerTestCase] - Count document in collection"""
         collection_test = CollectionTest()
@@ -223,4 +301,4 @@ def test_execute_simple_mapreduce_return_results_inline(self):
         self.assertEquals({u'_id': u'Value A', u'value': 2.0}, results[0])
         self.assertEquals({u'_id': u'Value B', u'value': 1.0}, results[1])
         self.assertEquals({u'_id': u'Value C', u'value': 1.0}, results[2])
-        self.assertEquals({u'_id': u'Value D', u'value': 1.0}, results[3])
\ No newline at end of file
+        self.assertEquals({u'_id': u'Value D', u'value': 1.0}, results[3])