class RestaurantChooserDatabase(object):
def __init__(self, init_db=False):
"""
Initializes the Restaurant Chooser Database object, which allows a user to interact with the
database associated with the application.
:param init_db: If true, the database will be deleted and then recreated with the default values set.
Set to False by default.
"""
self._db = DatabaseAccessor()
if (init_db):
clear_data(
) # Clears all data from the app data directory, including the database file
self._db.create_connection(
) # Creates a new database file if it doesn't exist)
if (init_db):
self._generate_initial_database_structure()
def _generate_initial_database_structure(self):
""" Creates the database tables and inserts the initial default values into them. """
# Generates tables for database if they do not already exist
for create_table_sql in CREATE_TABLES:
self._db.execute(create_table_sql)
# Inserts the default table values
for insert_sql in INITIAL_VALUE_INSERTS:
self._db._write_query(insert_sql)
def get_all(self, table_name):
"""
Gets all items from the given table.
:param table_name: Name of the table where data is being retrieved from.
:return: List of dictionaries for every queried item.
"""
if (table_name == "cuisine_types"):
return [
CuisineTypeModel(*param).parameters
for param in self._db.select_all_query(table_name)
]
elif (table_name == "item_types"):
return [
ItemTypeModel(*param).parameters
for param in self._db.select_all_query(table_name)
]
elif (table_name == "list_items"):
return [
ListItemModel(*param).parameters
for param in self._db.select_all_query(table_name)
]
elif (table_name == "restaurants"):
return [
RestaurantModel(*param).parameters
for param in self._db.select_all_query(table_name)
]
elif (table_name == "schedules"):
return [
ScheduleModel(*param).parameters
for param in self._db.select_all_query(table_name)
]
elif (table_name == "users"):
return [
UserModel(*param).parameters
for param in self._db.select_all_query(table_name)
]
else:
raise NotImplementedError(
"No implementation for given table name.")
def get_by_id(self, table_name, id):
"""
Gets an item with the given id from the given table.
:param table_name: Name of the table where data is being retrieved from.
:param id: Id of the item being queried.
:return: Dictionary containing parameters for the queried item.
"""
try:
items = self._db.select_all_query(table_name, {"id": id})
if (table_name == "cuisine_types"):
return CuisineTypeModel(
*items[0]).parameters if (len(items) > 0) else None
elif (table_name == "item_types"):
return ItemTypeModel(
*items[0]).parameters if (len(items) > 0) else None
elif (table_name == "list_items"):
return ListItemModel(
*items[0]).parameters if (len(items) > 0) else None
elif (table_name == "restaurants"):
return RestaurantModel(
*items[0]).parameters if (len(items) > 0) else None
elif (table_name == "schedules"):
return ScheduleModel(
*items[0]).parameters if (len(items) > 0) else None
elif (table_name == "users"):
return UserModel(
*items[0]).parameters if (len(items) > 0) else None
else:
raise NotImplementedError(
"No implementation for given table name.")
# Catches error where fatchall() is attempted on None - happens when invalid table name is passed
except AttributeError:
raise ValueError("Given table name doesn't exist within database.")
def insert_item(self, table_name, parameters):
"""
Inserts item with given parameters into the given table within the database.
:param table_name: Name of the table where data is being inserted into.
:param parameters: Dictionary containing the values to be inserted into the given table.
:return: Dictionary of parameters with database id added.
"""
id = self._db.insert_query(table_name, parameters)
parameters["id"] = id
return parameters
def update_item(self, table_name, id, parameters):
"""
Updates item within given table with new parameters.
:param table_name: Name of the table where data is being updated.
:param id: Identifier used to determine which item to update within the database.
:param parameters: Dictionary containing the column name->value mappings for data to be updated.
:return: Dictionary containing parameters for the updated item after update.
"""
self._db.update_query(table_name, parameters, {"id": id})
return self.get_by_id(table_name, id)
def delete_item(self, table_name, id):
"""
Deletes item with given id from the table.
:param table_name: Name of the table where data is being deleted.
:param id: Identifier used to determine which item to delete within the given table.
"""
if (self.get_by_id(table_name, id)):
self._db.delete_query(table_name, {"id": id})
else:
raise Exception(
"Illegal deletion attempted: record with id of {} cannot be found in the database."
.format(id))
# Item List functions
def _get_item_list(self, item_type):
"""
Gets the list of items of the given type.
:param item_type: Name of the item type.
:return: List of items of the given type.
"""
sql = "SELECT * FROM list_items WHERE item_type_id IN (SELECT id FROM item_types WHERE item_type='{}')".format(
item_type)
return self._db._read_query(sql)
def get_states(self):
"""
Gets the lists of states.
:return: List of dictionaries containing data for each state.
"""
return [
ListItemModel(*param).parameters
for param in self._get_item_list(STATE_ITEM_TYPE)
]
def get_weekdays(self):
"""
Gets the lists of weekdays.
:return: List of dictionaries containing data for each weekday.
"""
return [
ListItemModel(*param).parameters
for param in self._get_item_list(WEEKDAY_ITEM_TYPE)
]
# Other functions
def close_connection(self):
"""
Closes the connection to the SQLite database in order to free up resources.
"""
self._db.conn.close()
