Merge pull request #14 from fernandojunior/iss13

issue #13

.gitignore

@@ -65,3 +65,6 @@ target/
 db.*
 
 TODO*
+**.sqlite
+**.sqlite-journal
+**.env

README.md

@@ -99,6 +99,15 @@ Following a basic tutorial to demonstrate how to use the ORM.
     []
     ```
 
+## Linter
+
+Check code lint:
+
+```sh
+pip install pylint
+pylint orm.py
+```
+
 ## Contributing
 
 See [CONTRIBUTING](/CONTRIBUTING.md).

orm.py

@@ -16,17 +16,21 @@
 
 def attrs(obj):
     ''' Return attribute values dictionary for an object '''
-    return dict(i for i in vars(obj).items() if i[0][0] is not '_')
+    return dict(i for i in vars(obj).items() if i[0][0] != '_')
 
 
-def copy_attrs(obj, remove=[]):
+def copy_attrs(obj, remove=None):
     ''' Copy attribute values for an object '''
+    if remove is None:
+        remove = []
     return dict(i for i in attrs(obj).items() if i[0] not in remove)
 
 
 def render_column_definitions(model):
     ''' Create SQLite column definitions for an entity model '''
-    return ['%s %s' % (k, DATA_TYPES[v]) for k, v in attrs(model).items()]
+    model_attrs = attrs(model).items()
+    model_attrs = {k: v for k, v in model_attrs if k != 'db'}
+    return ['%s %s' % (k, DATA_TYPES[v]) for k, v in model_attrs.items()]
 
 
 def render_create_table_stmt(model):
@@ -37,17 +41,19 @@ def render_create_table_stmt(model):
     return sql.format(**params)
 
 
-class Database(object):
+class Database(object):  # pylint: disable=R0205
     ''' Proxy class to access sqlite3.connect method '''
 
     def __init__(self, *args, **kwargs):
         self.args = args
         self.kwargs = kwargs
+        self._connection = None
         self.connected = False
-        self.Model = type('Model%s' % str(self), (Model,), {'db': self})
+        self.Model = type('Model%s' % str(self), (Model,), {'db': self})  # pylint: disable=C0103
 
     @property
     def connection(self):
+        ''' Create SQL connection '''
         if self.connected:
             return self._connection
         self._connection = sqlite3.connect(*self.args, **self.kwargs)
@@ -56,22 +62,26 @@ def connection(self):
         return self._connection
 
     def close(self):
+        ''' Close SQL connection '''
         if self.connected:
             self.connection.close()
         self.connected = False
 
     def commit(self):
+        ''' Commit SQL changes '''
         self.connection.commit()
 
     def execute(self, sql, *args):
+        ''' Execute SQL '''
         return self.connection.execute(sql, args)
 
     def executescript(self, script):
+        ''' Execute SQL script '''
         self.connection.cursor().executescript(script)
         self.commit()
 
 
-class Manager(object):
+class Manager(object):  # pylint: disable=R0205
     ''' Data mapper interface (generic repository) for models '''
 
     def __init__(self, db, model, type_check=True):
@@ -83,19 +93,23 @@ def __init__(self, db, model, type_check=True):
             self.db.executescript(render_create_table_stmt(self.model))
 
     def all(self):
+        ''' Get all model objects from database '''
         result = self.db.execute('SELECT * FROM %s' % self.table_name)
         return (self.create(**row) for row in result.fetchall())
 
     def create(self, **kwargs):
+        ''' Create a model object '''
         obj = object.__new__(self.model)
         obj.__dict__ = kwargs
         return obj
 
     def delete(self, obj):
+        ''' Delete a model object from database '''
         sql = 'DELETE from %s WHERE id = ?'
         self.db.execute(sql % self.table_name, obj.id)
 
     def get(self, id):
+        ''' Get a model object from database by its id '''
         sql = 'SELECT * FROM %s WHERE id = ?' % self.table_name
         result = self.db.execute(sql, id)
         row = result.fetchone()
@@ -105,24 +119,28 @@ def get(self, id):
         return self.create(**row)
 
     def has(self, id):
+        ''' Check if a model object exists in database by its id '''
         sql = 'SELECT id FROM %s WHERE id = ?' % self.table_name
         result = self.db.execute(sql, id)
         return True if result.fetchall() else False
 
     def save(self, obj):
+        ''' Save a model object '''
         if 'id' in obj.__dict__ and self.has(obj.id):
             msg = 'Object%s id already registred: %s' % (self.model, obj.id)
             raise ValueError(msg)
         clone = copy_attrs(obj, remove=['id'])
         self.type_check and self._isvalid(clone)
         column_names = '%s' % ', '.join(clone.keys())
         column_references = '%s' % ', '.join('?' for i in range(len(clone)))
-        sql = 'INSERT INTO %s (%s) VALUES (%s)' % (self.table_name, column_names, column_references)  # noqa
+        sql = 'INSERT INTO %s (%s) VALUES (%s)'
+        sql = sql % (self.table_name, column_names, column_references)
         result = self.db.execute(sql, *clone.values())
         obj.id = result.lastrowid
         return obj
 
     def update(self, obj):
+        ''' Update a model object '''
         clone = copy_attrs(obj, remove=['id'])
         self.type_check and self._isvalid(clone)
         where_expressions = '= ?, '.join(clone.keys()) + '= ?'
@@ -146,27 +164,32 @@ def _isvalid(self, attr_values):
                 raise TypeError(msg % (attr, attr_types[attr], value_type))
 
 
-class Model(object):
+class Model(object):  # pylint: disable=R0205
     ''' Abstract entity model with an active record interface '''
 
     db = None
 
     def delete(self, type_check=True):
+        ''' Delete this model object '''
         return self.__class__.manager(type_check=type_check).delete(self)
 
     def save(self, type_check=True):
+        ''' Save this model object '''
         return self.__class__.manager(type_check=type_check).save(self)
 
     def update(self, type_check=True):
+        ''' Update this model object '''
         return self.__class__.manager(type_check=type_check).update(self)
 
     @property
     def public(self):
+        ''' Return the public model attributes '''
         return attrs(self)
 
     def __repr__(self):
         return str(self.public)
 
     @classmethod
     def manager(cls, db=None, type_check=True):
+        ''' Create a database managet '''
         return Manager(db if db else cls.db, cls, type_check)

tests.py

@@ -6,7 +6,6 @@
 
 
 class Post(db.Model):
-
     random = float
     text = str