def test_delete():
"""
Test the delete() method of the CarDAO class
"""
session = get_db_session()
car_record = CarDAO()
car_id = 1
result = car_record.delete(session, car_id)
print(result)
session.close()
class CarGUI():
"""
GUI class to perform CRUD operations on the Car table in the database.
"""
def __init__(self):
"""
Initialise CarGUI class.
"""
# Data access object
self.car_dao = CarDAO()
# Validation object
self.validator = Validation()
# Form fields
self.car_id = tk.StringVar()
self.make = tk.StringVar()
self.model = tk.StringVar()
self.registration = tk.StringVar()
self.manufacture_year = tk.StringVar()
self.colour = tk.StringVar()
# List of car ids
self.lb_ids = None
# Messagebox title
self.mb_title_bar = "Car CRUD"
pass
def create_gui(self, root):
"""
Create the GUI.
This is the interface for the user to input data or query the database.
It is composed of frames containing widgets (e.g. labels, input fields).
Parameters (apart from self):
root: main window of application
Return:
car_frame: the frame containing all the widgets for the car CRUD
"""
print("Creating Car GUI ...")
car_frame = tk.Frame(root)
car_frame.pack()
# FORM FRAME
form_frame = tk.Frame(car_frame)
form_frame.pack()
# FORM FRAME: ROW 0
# Heading for Car frame
tk.Label(form_frame, text="Car", font=('arial', 10)).grid(row=0,
column=0,
columnspan=3)
# FORM FRAME: ROW 1
# Label and entry field (disabled) for "Car ID"
tk.Label(form_frame,
text="Car ID",
font=('arial', 10),
width=20,
anchor='e',
bd=1,
pady=10,
padx=10).grid(row=1, column=0)
tk.Entry(form_frame,
textvariable=self.car_id,
width=30,
bd=1,
state=tk.DISABLED).grid(row=1, column=1)
# Heading for Listbox to display and select Car IDs
tk.Label(form_frame, text="Car IDs", font=('arial', 10)).grid(row=1,
column=2)
# FORM FRAME: ROW 2
# Label and entry field for "Make"
tk.Label(form_frame,
text="Make",
font=('arial', 10),
width=20,
anchor='e',
bd=1,
pady=10,
padx=10).grid(row=2, column=0)
tk.Entry(form_frame, textvariable=self.make, width=30,
bd=1).grid(row=2, column=1)
# Listbox to display and select Car IDs
self.lb_ids = tk.Listbox(form_frame)
self.lb_ids.grid(row=2, column=2, rowspan=5)
self.lb_ids.bind('<<ListboxSelect>>', self.on_list_select)
# FORM FRAME: ROW 3
# Label and entry field for "Model"
tk.Label(form_frame,
text="Model",
font=('arial', 10),
width=20,
anchor='e',
bd=1,
pady=10,
padx=10).grid(row=3, column=0)
tk.Entry(form_frame, textvariable=self.model, width=30,
bd=1).grid(row=3, column=1)
# FORM FRAME: ROW 4
# Label and entry field for "Registration"
tk.Label(form_frame,
text="Registration",
font=('arial', 10),
width=20,
anchor='e',
bd=1,
pady=10,
padx=10).grid(row=4, column=0)
tk.Entry(form_frame, textvariable=self.registration, width=30,
bd=1).grid(row=4, column=1)
# FORM FRAME: ROW 5
# Label and entry field for "Manufacture Year"
tk.Label(form_frame,
text="Manufacture Year",
font=('arial', 10),
width=20,
anchor='e',
bd=1,
pady=10,
padx=10).grid(row=5, column=0)
tk.Entry(form_frame,
textvariable=self.manufacture_year,
width=30,
bd=1).grid(row=5, column=1)
# FORM FRAME: ROW 6
# Label and entry field for "Colour"
tk.Label(form_frame,
text="Colour",
font=('arial', 10),
width=20,
anchor='e',
bd=1,
pady=10,
padx=10).grid(row=6, column=0)
tk.Entry(form_frame, textvariable=self.colour, width=30,
bd=1).grid(row=6, column=1)
# BUTTON FRAME
button_frame = tk.Frame(car_frame, pady=10)
button_frame.pack()
tk.Button(button_frame,
width=10,
text="Clear",
command=self.clear_fields).pack(side=tk.LEFT)
tk.Button(button_frame, width=10, text="Save",
command=self.save).pack(side=tk.LEFT)
tk.Button(button_frame, width=10, text="Delete",
command=self.delete).pack(side=tk.LEFT)
tk.Button(button_frame, width=10, text="Load",
command=self.load).pack(side=tk.LEFT)
return car_frame
def clear_fields(self):
"""
Clear the fields of the form
Parameters (apart from self): None
Return: None
"""
self.car_id.set("")
self.make.set("")
self.model.set("")
self.registration.set("")
self.manufacture_year.set("")
self.colour.set("")
pass
def save(self):
"""
Save the data displayed on the form to the database.
Get car data to be saved from the global instance attributes,
then validate data by calling validate_fields()
If the data is invalid, a message box is presented to the user.
If the data is valid, the data is either saved or updated
If car_id is present, the data is updated
If not, a new car record is created in the database
Parameters (apart from self): None
Return: None
"""
print("Saving a car ...")
data = self.get_fields()
valid_data, message = self.validate_fields(data)
if valid_data:
if (len(data['car_id']) == 0):
print("Calling create() as car_id is absent")
self.create(data)
else:
print("Calling update() as car_id is present")
self.update(data)
pass
else:
message_text = "Invalid fields.\n" + message
messagebox.showwarning(self.mb_title_bar,
message_text,
icon='warning')
pass
def get_fields(self):
"""
Get the data entered in the fields of the form
Parameters (apart from self): None
Return:
car_record: dictionary object containing all the information
about a car
"""
car_record = {}
car_record['car_id'] = self.car_id.get()
car_record['make'] = self.make.get()
car_record['model'] = self.model.get()
car_record['registration'] = self.registration.get()
car_record['manufacture_year'] = self.manufacture_year.get()
car_record['colour'] = self.colour.get()
return car_record
def validate_fields(self, data):
"""
Validate the data entered in the fields of the form
Parameters (apart from self):
data: dictionary object containing all the information entered on the form
Return:
valid_data: a boolean indication whether the data is valid (True) or
not valid (False)
message: a string containing details about the fields that are not valid
Returned as a tuple (valid_data, message)
"""
valid_data = True
message_list = []
# Check field is not empty
if len(data['make']) == 0:
valid_data = False
message_list.append("make is empty")
if len(data['model']) == 0:
valid_data = False
message_list.append("model is empty")
if len(data['registration']) == 0:
valid_data = False
message_list.append("registration is empty")
if len(data['manufacture_year']) == 0:
valid_data = False
message_list.append("manufacture year is empty")
if len(data['colour']) == 0:
valid_data = False
message_list.append("colour is empty")
# Check that colour and make are alphabetic
if not self.validator.is_alphabetic(data['colour']):
valid_data = False
message_list.append("invalid colour")
if not self.validator.is_alphabetic(data['make']):
valid_data = False
message_list.append("invalid make")
# Model can contain numbers e.g. Mazda2
if not self.validator.is_alphanumeric(data['model']):
valid_data = False
message_list.append("invalid model")
# Other checks
if not self.validator.is_manufacture_year(data['manufacture_year']):
valid_data = False
message_list.append("invalid manufacture year")
if not self.validator.is_registration(data['registration']):
valid_data = False
message_list.append("invalid registration")
message = ', '.join(message_list)
return valid_data, message
pass
def create(self, data):
"""
Create a new record in the database.
A messagebox is used display the outcome (success or failure)
of the create operation to the user.
Parameters (apart from self):
data: dictionary object containing car data to be saved
Return: None
"""
print("Creating a car ...")
print(data)
session = db.get_db_session()
result = self.car_dao.create(session, data)
session.close()
messagebox.showinfo(self.mb_title_bar, result)
pass
def update(self, data):
"""
Update a record in the database.
A messagebox is used display the outcome (success or failure)
of the update operation to the user.
Parameters (apart from self):
data: dictionary object containing car data to be saved
Return: None
"""
print("Updating a car ...")
print(data)
session = db.get_db_session()
result = self.car_dao.update(session, data['car_id'], data)
session.close()
messagebox.showinfo(self.mb_title_bar, result)
pass
def delete(self):
"""
Delete a record from the database.
The car_id of the record to be deleted is obtained from a
global attribute.
A messagebox is used display the outcome (success or failure)
of the delete operation to the user.
Parameters (apart from self): None
Return: None
"""
print("Deleting a car ...")
car_record_id = self.car_id.get()
print(id)
session = db.get_db_session()
result = self.car_dao.delete(session, car_record_id)
session.close()
messagebox.showinfo(self.mb_title_bar, result)
pass
def load(self):
"""
Retrieve a list of IDs from the database and load them into a listbox.
Parameters (apart from self):
Return: None
"""
session = db.get_db_session()
result = self.car_dao.find_ids(session)
session.close()
print("result: ", result)
if "car_ids" in result:
list_ids = result["car_ids"]
self.lb_ids.delete(0, tk.END)
print("Setting car_id in listbox")
for x in list_ids:
self.lb_ids.insert(tk.END, x)
pass
def on_list_select(self, evt):
"""
Actions to be triggered when a user clicks an item in the listbox.
Defined above in create_gui(), where on_list_select is bound to the
listbox selection.
Parameters (apart from self):
evt: object containing information about the mouse click
Return: None
"""
w = evt.widget
index = int(w.curselection()[0])
value = w.get(index)
print(index)
print(value)
session = db.get_db_session()
result = self.car_dao.find_by_id(session, value)
session.close()
print("result: ", result)
car_record = result['car']
self.populate_fields(car_record)
pass
def populate_fields(self, car_record):
"""
Populate the fields of the form with data.
Parameters (apart from self):
car_record: dictionary object containing all the information
about a car
Return: None
"""
self.car_id.set(car_record['car_id'])
self.make.set(car_record['make'])
self.model.set(car_record['model'])
self.registration.set(car_record['registration'])
self.manufacture_year.set(car_record['manufacture_year'])
self.colour.set(car_record['colour'])
pass