def test_delete():
session = get_db_session()
vhc = VehicleDAO()
vehicle_id = 1
result = vhc.delete(session, vehicle_id)
print(result)
session.close()
class VehicleGUI():
"""
GUI class to perform CRUD operations on the vehicle table in the database.
"""
def __init__(self):
"""
The initialiser is used to "instantiate" attributes of the class.
The attributes are the "variables" that have been declared "outside"
of the methods of the class.
Some attributes may have not been declared as they may be created
any where in the class methods (python allows this).
Attributes are like global variables for the class, as they are
available to any method in the class.
And, to use them, they must be prefixed with "self."
This differentiates them from "local" variables which are
defined/created and used within a single method
If you need to pass the value of a local variable from one method
to another, then you must pass "parameters" to the method
We cannot create the GUI here as we need to return a reference to
the frame created.
Hence, we need to implement a 'normal' function to do this e.g. create_gui()
Parameters (apart from self): None
Return: None
"""
# Instantiate a data access object
# Contains methods to access the database
self.vhc_dao = VehicleDAO()
# Instantiate a validation object
# Contains methods to validate input fields
self.validator = Validation()
# Form fields
# Instantiate stringvars - hold data entered in fields of form
self.vehicle_id = tk.StringVar()
self.vehicle_make = tk.StringVar()
self.vehicle_model = tk.StringVar()
self.year_manu = tk.StringVar()
self.vehicle_price = tk.StringVar()
# List of vehicle ids - lb for listbox
self.lb_ids = None
# Messagebox title
self.mb_title_bar = "Vehicle CRUD"
pass
def create_gui(self, root):
"""
Create a high level frame which contains the entire GUI
(of this part of the application) and adds it to the root window.
Notice that the "root" window is passed the second parameter in the
method header.
Also notice that the first (and mandatory) parameter to all methods
is "self" i.e. a reference to the object instantiated from the class.
Widgets like labels, entries, etc (including inner frames) are added
to the high level frame
At the end, the function return a reference to the frame that was
created for the calling program to be able to access it.
Parameters (apart from self):
root: main window of application
Return:
vhc_frame: the frame containing all the widgets for the vehicle CRUD
"""
# Good practice to print something at the start of the method
# e.g. which method is being executed, the values of parameters passes,
# etc
# Good for tracing the execution of the program while debugging it
# After debugging, you may want to "comment out" some of the
# print statements so that they do not execute and print too
# much stuff in the console
print("Creating vehicle GUI ...")
# vhc_frame = tk.Frame(root).pack()
# cannot write the above as pack() does not return anything
# and need the variable name to refer to it elsewhere
# DO NOT SPECIFY ANY WIDTH AND HEIGHT OF THE FRAMES
# HERE FOR FLEXIBILITY REASONS
# The height and width or the root window can be specified
# in the main GUI (or in the main() method)
vhc_frame = tk.Frame(root)
vhc_frame.pack()
# Add a frame to contain the form widgets
# For 'tkinter frame' options,
# refer to http://effbot.org/tkinterbook/frame.htm
# For 'tkinter pack' options,
# refer to http://effbot.org/tkinterbook/pack.htm
# To put a number of widgets in a column one on top of the other,
# just use pack() without any options
# Use the fill=tk.X option to make all widgets as wide as the parent widget
# To pack widgets side by side, use the side option
# e.g. side=tk.LEFT, tk.BOTTOM, tk.RIGHT (default is tk.TOP)
# Use the fill=tk.Y option to make all widgets as tall as the parent widget
# have also fill=tk.BOTH option
# The anchor= option is used to position the widget in the container,
# default is tk.CENTER
# Internal padding around widgets: ipadx= and ipady= default is 0
# External padding arounf widgets: padx= pady= default is 0
form_frame = tk.Frame(vhc_frame)
form_frame.pack()
# row 0: title label
# The variable name is not needed
# For 'tkinter label' options,
# refer to http://effbot.org/tkinterbook/label.htm
# By default, the text is centered
# To right align use anchor=e (east) not justify=RIGHT which is used
# for aligning multiple lines
# Labels have padx= and pady= options but no ipadx= and ipady=
# Check the ulr above, to finc out more about the many options
# available for configuring labels!!!
# STICK TO THE DEFAULT VALUES,
# UNLESS YOU HAVE A GOOD REASON TO CHANGE THEM!!!!!!!!!!!!!!!!
# For 'tkinter grid' options,
# refer to http://effbot.org/tkinterbook/grid.htm
# For spanning multiple rows and columns,
# use rowspan= and columnspan= options (default is 1)
# Use the sticky= option for positioning
# (instead of anchor= as used in pack) -
# (default is centered) values are: n, w, e, w, nw, etc
# Internal padding around widgets: ipadx= and ipady= default is 0
# External padding around widgets: padx= pady= default is 0
# Use the width= option to specify how wide in terms of number of characters
tk.Label(form_frame, font=('arial', 10),
text="Vehicle").grid(row=0, column=0, columnspan=3)
# row 1: vehicle_id label, vehicle_id entry and list_of_ids label
tk.Label(form_frame,
text="Vehicle Id",
font=('arial', 10),
width=20,
anchor="e",
bd=1,
pady=10,
padx=10).grid(row=1, column=0)
# Need to use both padx and pady to leave a vertical space between rows of labels
# And a space between the label and its entry field
# For 'tkinter Entry' options,
# refer to http://effbot.org/tkinterbook/entry.htm
# Entry has no padding options
# Use the width= option to specify how wide in terms of number of characters
tk.Entry(form_frame,
textvariable=self.vehicle_id,
width=30,
bd=1,
state=tk.DISABLED).grid(row=1, column=1)
# vehicle_id is disabled to prevent user from entering a value
# vehicle_id is generated by the database because AUTOINCREMENT
# was specified in the database schema
tk.Label(form_frame, text="Vehicle IDs",
font=('arial', 10)).grid(row=1, column=2)
# row 2: vehicle_make label, vehicle_make entry and listbox of ids
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.vehicle_make, width=30,
bd=1).grid(row=2, column=1)
# For 'tkinter Listbox' options,
# refer to http://effbot.org/tkinterbook/listbox.htm
# Use the height= option to specify the height, default is 10
# Use the width= option to specify the number of characters, default is 20
self.lb_ids = tk.Listbox(form_frame)
self.lb_ids.grid(row=2, column=2, rowspan=5)
# 'self' means instance attribute rather than local variable
# since python allows using variables before they are declared
# it does not matter whether lb_ids has been declared or not at the
# top of the file before the methods definition
# Set the method to be called when an item is clicked on the listbox
self.lb_ids.bind('<<ListboxSelect>>', self.on_list_select)
# row 3: vehicle_model label and entry (the listbox will go through)
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.vehicle_model, width=30,
bd=1).grid(row=3, column=1)
# row 4: title label and combobox (the listbox will go through)
# tk.Label(form_frame, text= "Title", font=('arial', 10), width=20,
# anchor="e", bd=1, pady=10, padx=10).grid(row=4, column=0)
# Readonly combobox - prevent the user from adding values
# For 'tkinter Combobox' options,
# refer to https://docs.python.org/3.1/library/tkinter.ttk.html
# Cannot find a good reference!
# The state= option is either "normal" for read/write or "readonly"
# to prevent the user from adding values
#VALUES = ('Mr','Mrs','Ms', 'Miss', 'Dr')
#ttk.Combobox(form_frame, state="readonly", textvariable=self.title,
# values=VALUES, width=10).grid(row=4, column=1, sticky="w")
# Display first value - prevents a blank value being displayed (and selected!)
#self.title.set(VALUES[0])
# row 5: year_manu label and combobox (the listbox will go through)
tk.Label(form_frame,
text="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.year_manu, width=30,
bd=1).grid(row=5, column=1)
# row 6: vehicle_price label and combobox (the listbox will go through)
tk.Label(form_frame,
text="Price",
font=('arial', 10),
width=20,
anchor="e",
bd=1,
pady=10,
padx=10).grid(row=6, column=0)
tk.Entry(form_frame, textvariable=self.vehicle_price, width=30,
bd=1).grid(row=6, column=1)
# Buttons
# There are 3 columns of widgets in the frame and 4 buttons
# Better insert the button in another frame
# Also easier to pack them from the left than using a grid with row
# and col locations
# pady to leave a space from frame on top
button_frame = tk.Frame(vhc_frame, pady=10)
button_frame.pack()
# For 'tkinter Button' options,
# refer to http://effbot.org/tkinterbook/button.htm
# Use the anchor= option to position the button
# External padding around buttons: padx= pady= default is 0
# Use the width= option to specify the number of characters,
# otherwise calculated based on text width
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 a reference to the high level frame created
# Will need the reference to be able to destroy it in the calling function
return vhc_frame
def clear_fields(self):
"""
Clear the fields of the form
Parameters (apart from self): None
Return: None
"""
# Just blank all the fields
self.vehicle_id.set("")
self.vehicle_make.set("")
self.vehicle_model.set("")
#self.title.set("") # Do not clear if using dropdown
self.year_manu.set("")
self.vehicle_price.set("")
pass
def save(self):
"""
Save the data displayed on the form to the database.
The vehicle data to be saved is obtained from the global
instance attributes.
The data is validated by calling another method called 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 an vehicle_id is present, the data is updated
If not, a new vehicle record is create in the database
Parameters (apart from self): None
Return: None
"""
print("Saving a Vehicle ...")
# Get the data
data = self.get_fields()
# Validate the data
valid_data, message = self.validate_fields(data)
if valid_data:
if (len(data['vehicle_id']) == 0):
# If nothing has been entered in vehicle_id
# i.e. its length is zero characters
print("Calling create() as vehicle_id is absent")
self.create(data)
else:
print("Calling update() as vehicle_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:
vhc: dictionary object containing all the information
about an vehicle
"""
vhc = {}
# vehicle_id is ignored when creating a record
vhc['vehicle_id'] = self.vehicle_id.get()
vhc['vehicle_make'] = self.vehicle_make.get()
vhc['vehicle_model'] = self.vehicle_model.get()
vhc['year_manu'] = self.year_manu.get()
vhc['vehicle_price'] = self.vehicle_price.get()
return vhc
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
Note: when these values are returned as a tuple
(valid_data, message) i.e. a list that cannot be changed
"""
# By default set to true, anything wrong will turn it to false
valid_data = True
# Instantiate an vhcty list to contain the messages
message_list = []
# Check for blank fields
# Do not check vehicle_id as this is generated by the database
#if len(data['vehicle_id']==0:
# valid_data = False
# message_list.append("vehicle_id is vhcty")
if len(data['vehicle_make']) == 0:
valid_data = False
message_list.append("vehicle_make is vhcty")
if len(data['vehicle_model']) == 0:
valid_data = False
message_list.append("vehicle_model is vhcty")
if len(data['year_manu']) == 0:
valid_data = False
message_list.append("year_manu is vhcty")
if len(data['vehicle_price']) == 0:
valid_data = False
message_list.append("vehicle_price is vhcty")
# Other possible checks
# Implement these as functions in the Validation class so that
# other classes can call them
# Check if vehicle_make and vehicle_model contain
# only alphabetic characters (and may be certain special characters)
if not self.validator.is_alphabetic(data['vehicle_make']):
valid_data = False
message_list.append("invalid vehicle_make")
if not self.validator.is_alphabetic(data['vehicle_model']):
valid_data = False
message_list.append("invalid vehicle_model")
# Check if title is in a list [Mr, Ms, Mrs, Dr, etc]
# Alternatively could use a dropbox/combobox to do this
# However, if the combobox is not set to a default value
# (to force the user to select something)
# A blank value can get through
# if self.title.get() not in ["Mr", "Ms", "Mrs", "Miss", "Dr"]:
# valid_data = False
# message_list.append("title should be Mr, Ms, Mrs, Miss or Dr")
# Check if year_manu follows a certain pattern
# i.e contains an @ followed by a dot
if not self.validator.is_year_manu(data['year_manu']):
valid_data = False
message_list.append("invalid Year format")
# Check if vehicle_price follows a certain pattern
# i.e. (02) 99999999 or (02) 9999 9999 or +61 3 9999 9999 (international)
#if not self.validator.is_phone_number(data['vehicle_price']):
# valid_data = False
# message_list.append("invalid phone number format")
# Join the items in the list as a string separated with a comma and a space
message = ', '.join(message_list)
return valid_data, message # return 2 values
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 vehicle data to be saved
Return: None
"""
print("Creating a vehicle ...")
print(data)
session = db.get_db_session() # Get a session (database.py)
result = self.vhc_dao.create(session, data)
# result is a tuple e.g. ("vehicle added successfully", 1004)
#result, vehicle_id = self.vhc.create(data)
# if you wish to get the message and vehicle_id separately
session.close() # Close the session
# Display the returned message to the user - use a messagebox
# For 'tkinter messagebox' options,
# refer to http://effbot.org/tkinterbook/tkinter-standard-dialogs.htm
# Format: message.function(title, message [, options])
# Functions: showinfo, showwarning, showerror, askquestion,
# askokcancel, askyesno, or askretrycancel
# Use the icon= option to specify which icon to display
# e.g. icon="warning", "error", "info", "question"
# Display everything that is returned in the result
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 vehicle data to be saved
Return: None
"""
print("Updating a vehicle ...")
print(data)
session = db.get_db_session() # Get a session (database.py)
result = self.vhc_dao.update(session, data['vehicle_id'], data)
session.close() # close the session
# Display the returned message to the user - use a messagebox
# Display everything that is returned in the result
messagebox.showinfo(self.mb_title_bar, result)
pass
def delete(self):
"""
Delete a record from the database
The vehicle_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
"""
# Grab the vehicle_id from the stringvar
id = self.vehicle_id.get()
print(id)
# Call the data access object to do the job
# Pass the id as parameter to the delete() method
session = db.get_db_session() # Get a session (database.py)
result = self.vhc_dao.delete(session, id)
session.close() # Close the session
# Display the returned message to the user - use a messagebox
# Display everything that is returned in the result
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() # Get a session (database.py)
result = self.vhc_dao.find_ids(session) # {"vehicle_ids": [1, 2, 3]}
session.close() # Close the session
print("result", result)
# Check if there is an entry in the result dictionary
if "vehicle_ids" in result:
list_ids = result[
'vehicle_ids'] # will crash if there is no entry!
# Set the returned list into the listbox
# Before doing that, must clear any previous list in the box
self.lb_ids.delete(0, tk.END)
print("Setting vehicle_id in listbox ...")
for x in list_ids:
self.lb_ids.insert(tk.END, x)
#print(x)
pass
def on_list_select(self, evt):
"""
on_list_select() is triggered when a user clicks an item in the listbox.
This was defined with the statement
"self.lb_ids.bind('<<ListboxSelect>>', self.on_list_select)"
defined above in create_gui()
Parameters (apart from self):
evt: object containing information about the mouse click
Return: None
"""
# For more information on 'tkinter events',
# refer to http://effbot.org/tkinterbook/tkinter-events-and-bindings.htm
w = evt.widget
index = int(w.curselection()[0])
# index = position of the item clicked in the list, first item is item 0 not 1
value = w.get(index)
# value of the item clicked, in our case it's the vehicle_id
print(index)
print(value)
# Call find_by_id and populate the stringvars of the form
session = db.get_db_session() # Get a session (database.py)
result = self.vhc_dao.find_by_id(session, value)
session.close() # close the session
print("result", result)
# { "vehicle" : {"vehicle_id": "", "vehicle_make": "", etc}}
vhc = result['vehicle']
self.populate_fields(vhc)
pass
def populate_fields(self, vhc):
"""
Populate the fields of the form with data
Parameters (apart from self):
vhc: dictionary object containing all the information about an vehicle
Return:
"""
# Set the values from the dict to the stringvars
self.vehicle_id.set(vhc['vehicle_id'])
self.vehicle_make.set(vhc['vehicle_make'])
self.vehicle_model.set(vhc['vehicle_model'])
self.year_manu.set(vhc['year_manu'])
self.vehicle_price.set(vhc['vehicle_price'])
pass