Task 06: still in development

console.py

@@ -12,7 +12,6 @@
 from models.place import Place
 from models.review import Review
 from models import storage
-from models.engine.file_storage import FileStorage
 
 
 class HBNBCommand(cmd.Cmd):

models/__init__.py

@@ -1,7 +1,12 @@
 #!/usr/bin/python3
-"""This module instantiates an object of class FileStorage"""
-from models.engine.file_storage import FileStorage
+"""This module instantiates the storage medium"""
+import os
 
+if os.environ.get('HBNB_TYPE_STORAGE') == 'db':
+    from models.engine.db_storage import DBStorage
+    storage = DBStorage()
+else:
+    from models.engine.file_storage import FileStorage
+    storage = FileStorage()
 
-storage = FileStorage()
 storage.reload()

models/base_model.py

@@ -14,17 +14,16 @@ class BaseModel:
     id = Column(String(60), nullable=False, primary_key=True)
     created_at = Column(DateTime, nullable=False, default=datetime.utcnow())
     updated_at = Column(DateTime, nullable=False, default=datetime.utcnow())
+
     def __init__(self, *args, **kwargs):
         """Instatntiates a new model"""
         if not kwargs:
             self.id = str(uuid.uuid4())
             self.created_at = datetime.now()
-            self.updated_at = datetime.now()
+            self.updated_at = self.created_at
         else:
-            kwargs['updated_at'] = datetime.strptime(kwargs['updated_at'],
-                                                     '%Y-%m-%dT%H:%M:%S.%f')
-            kwargs['created_at'] = datetime.strptime(kwargs['created_at'],
-                                                     '%Y-%m-%dT%H:%M:%S.%f')
+            for at in ['created_at', 'updated_at']:
+                kwargs[at] = datetime.fromisoformat(kwargs[at])
             del kwargs['__class__']
             self.__dict__.update(kwargs)
 
@@ -48,10 +47,14 @@ def to_dict(self):
                           (str(type(self)).split('.')[-1]).split('\'')[0]})
         dictionary['created_at'] = self.created_at.isoformat()
         dictionary['updated_at'] = self.updated_at.isoformat()
+        try:
+            del dictionary['_sa_instance_state']
+        except KeyError:
+            pass
         return dictionary
 
 
     def delete(self):
         """Delete the class instance"""
         from models import storage
-        del storage.all()[self.to_dict()['__class__'] + '.' + self.id]
+        storage.delete(self)

models/city.py

@@ -1,9 +1,12 @@
 #!/usr/bin/python3
 """ City Module for HBNB project """
-from models.base_model import BaseModel
+from models.base_model import BaseModel, Base
+from sqlalchemy import Column, String, ForeignKey
+from sqlalchemy.orm import relationship
 
 
-class City(BaseModel):
+class City(BaseModel, Base):
     """ The city class, contains state ID and name """
-    state_id = ""
-    name = ""
+    __tablename__ = 'cities'
+    name = Column(String(128), nullable=False)
+    state_id = Column(String(60), ForeignKey('states.id'), nullable=False)

models/engine/db_storage.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+"""Defines a new engine that uses SQLAlchemy"""
+import os
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, scoped_session
+
+
+class DBStorage:
+    """DBStorage Engine running on SQLAlchemy"""
+
+    __engine = None
+    __session = None
+
+    def __init__(self):
+        """class constructor for DBStorage"""
+
+        credentials = ['HBNB_MYSQL_USER', 'HBNB_MYSQL_PWD',
+                       'HBNB_MYSQL_HOST', 'HBNB_MYSQL_DB']
+        env = [os.environ.get(c) for c in credentials]
+        e = 'mysql+mysqldb://{}:{}@{}/{}'.format(*env[:])
+        self.__engine = create_engine(e, pool_pre_ping=True)
+        Session = sessionmaker(bind=self.__engine)
+        self.__session = Session()
+
+        #  drop all tables if the environment variable
+        #  HBNB_ENV is equal to test
+        if os.environ.get('HBNB_ENV') == 'test':
+            from models.base_model import Base
+            Base.metadata.drop_all(self.__engine)
+
+
+    def all(self, cls=None):
+        """Queries the current database session (self.__session)
+        for all objects depending of the class name (argument cls)"""
+        from models.user import User
+        from models.state import State
+        from models.city import City
+        from models.amenity import Amenity
+        from models.place import Place
+        from models.review import Review
+
+        class_list = [User, State, City, Amenity, Place, Review]
+        objs = {}
+        if cls is not None:
+            for obj in self.__session.query(cls).all():
+                objs.update({obj.to_dict()['__class__'] + '.' + obj.id: obj})
+        else:
+            for class_item in class_list:
+                for obj in self.__session.query(class_item).all():
+                    objs.update({obj.to_dict()['__class__'] + '.' + obj.id: obj})
+        return objs
+
+    def new(self, obj):
+        """Add obj to the current database session"""
+        self.__session.add(obj)
+
+    def save(self):
+        """Commit all changes of the current database session"""
+        self.__session.commit()
+
+    def delete(self, obj=None):
+        """Delete from the current database session obj if not None"""
+        if obj is not None:
+            self.__session.delete(obj)
+
+    def reload(self):
+        """Create all tables in the database
+        """
+        from models.user import User
+        from models.state import State
+        from models.city import City
+        from models.amenity import Amenity
+        from models.place import Place
+        from models.review import Review
+        from models.base_model import Base
+
+        Base.metadata.create_all(self.__engine)
+        Session = sessionmaker(bind=self.__engine, expire_on_commit=False)
+        self.__session = scoped_session(Session)

models/state.py

@@ -1,8 +1,17 @@
 #!/usr/bin/python3
 """ State Module for HBNB project """
-from models.base_model import BaseModel
+from models.base_model import BaseModel, Base
+from sqlalchemy import Column, String
+from sqlalchemy.orm import relationship
 
 
-class State(BaseModel):
+class State(BaseModel, Base):
     """ State class """
-    name = ""
+    __tablename__ = 'states'
+    name = Column(String(128), nullable=False)
+    cities = relationship('City', cascade='all, delete', backref='state')
+
+    @property
+    def cities(self):
+        """A getter for the attribute cities"""
+        return [city for city in self.cities if city.state_id == self.id]