Task 07

models/engine/db_storage.py

@@ -1,86 +1,83 @@
 #!/usr/bin/python3
-"""This module defines a class to manage db storage for hbnb clone"""
+"""Defines a new engine that uses SQLAlchemy"""
+import os
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker, scoped_session
-from ..base_model import Base, BaseModel
-from os import getenv
-from sqlalchemy import create_engine, inspect
-
-HBNB_MYSQL_USER = getenv('HBNB_MYSQL_USER')
-HBNB_MYSQL_PWD = getenv('HBNB_MYSQL_PWD')
-HBNB_MYSQL_HOST = getenv('HBNB_MYSQL_HOST')
-HBNB_MYSQL_DB = getenv('HBNB_MYSQL_DB')
-HBNB_MYSQL_PORT = getenv('HBNB_MYSQL_PORT')
-HBNB_ENV = 'dev'
 
 
 class DBStorage:
-    """This class manages storage of hbnb . in database"""
+    """DBStorage Engine running on SQLAlchemy"""
+
     __engine = None
     __session = None
 
     def __init__(self):
-        """initializes the database"""
-        self.__engine = create_engine('mysql+mysqldb://{}:{}@{}/{}'
-                                      .format(HBNB_MYSQL_USER, HBNB_MYSQL_PWD,
-                                              HBNB_MYSQL_HOST, HBNB_MYSQL_DB),
-                                      pool_pre_ping=True)
-        if HBNB_ENV == 'test':
+        """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):
-        """Returns a dictionary of all instances of a given class"""
-        from ..user import User
-        from ..state import State
-        from ..city import City
-        from ..place import Place
-        from ..review import Review
-        from ..amenity import Amenity
+        """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
 
-        result_dict = {}
-        for model in [User, State, City, Place, Amenity, Review]:
-            if cls is not None and model != cls:
-                continue
-            query_results = self.__session.query(model).all()
-            for obj in query_results:
-                key = "{}.{}".format(type(obj).__name__, obj.id)
-                result_dict[key] = obj
-        return result_dict
+        class_list = [State, City, User, Place, Review, Amenity]
+        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():
+                    key = obj.to_dict()['__class__'] + '.' + obj.id
+                    objs.update({key: obj})
+        return objs
 
     def new(self, obj):
-        """Adds new object to storage dictionary"""
-        if obj:
-            try:
-                self.__session.add(obj)
-                self.__session.flush()
-                self.__session.refresh(obj)
-            except Exception:
-                self.__session.rollback()
+        """Add obj to the current database session"""
+        self.__session.add(obj)
 
     def save(self):
-        """Saves storage dictionary to file"""
+        """Commit all changes of the current database session"""
         self.__session.commit()
 
     def delete(self, obj=None):
-        """delete obj from __objects if it’s inside"""
+        """Delete from the current database session obj if not None"""
         if obj is not None:
             self.__session.delete(obj)
 
     def reload(self):
-        """Loads storage dictionary from file"""
-        from ..user import User
-        from ..state import State
-        from ..city import City
-        from ..place import Place
-        from ..review import Review
-        from ..amenity import Amenity
+        """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_factory = sessionmaker(
-            bind=self.__engine, expire_on_commit=False)
-        self.__session = scoped_session(session_factory)()
+        Session = sessionmaker(bind=self.__engine, expire_on_commit=False)
+        self.__session = scoped_session(Session)
 
     def close(self):
-        """calls remove() method on the private
-        session attribute (self.__session)"""
+        """call close() method for commiting objects to db"""
         self.__session.close()