Class and Object Terms

The foundations of Object-Oriented Programming is defining a Class

  • In Object-Oriented Programming (OOP), a class is a blueprint for creating an Object. (a data structure). An Object is used like many other Python variables.
  • A Class has ...
    • a collection of data, these are called Attributes and in Python are pre-fixed using the keyword self
    • a collection of Functions/Procedures. These are called *Methods when they exist inside a Class definition.
  • An Object is created from the Class/Template. Characteristics of objects ...
    • an Object is an Instance of the Class/Template
    • there can be many Objects created from the same Class
    • each Object contains its own Instance Data
    • the data is setup by the Constructor, this is the "init" method in a Python class
    • all methods in the Class/Template become part of the Object, methods are accessed using dot notation (object.method())
  • A Python Class allow for the definition of @ decorators, these allow access to instance data without the use of functions ...
    • @property decorator (aka getter). This enables developers to reference/get instance data in a shorthand fashion (object.name versus object.get_name())
    • @name.setter decorator (aka setter). This enables developers to update/set instance data in a shorthand fashion (object.name = "John" versus object.set_name("John"))
    • observe all instance data (self._name, self.email ...) are prefixed with "", this convention allows setters and getters to work with more natural variable name (name, email ...)

Class and Object Code

# Werkzeug is a collection of libraries that can be used to create a WSGI (Web Server Gateway Interface)
# A gateway in necessary as a web server cannot communicate directly with Python.
# In this case, imports are focused on generating hash code to protect passwords.
from werkzeug.security import generate_password_hash, check_password_hash
import json

# Define a User Class/Template
# -- A User represents the data we want to manage
class User:    
    # constructor of a User object, initializes the instance variables within object (self)
    def __init__(self, name, uid, password):
        self._name = name    # variables with self prefix become part of the object, 
        self._uid = uid
        self.set_password(password)

    # a name getter method, extracts name from object
    @property
    def name(self):
        return self._name
    
    # a setter function, allows name to be updated after initial object creation
    @name.setter
    def name(self, name):
        self._name = name
    
    # a getter method, extracts email from object
    @property
    def uid(self):
        return self._uid
    
    # a setter function, allows name to be updated after initial object creation
    @uid.setter
    def uid(self, uid):
        self._uid = uid
        
    # check if uid parameter matches user id in object, return boolean
    def is_uid(self, uid):
        return self._uid == uid
    
    @property
    def password(self):
        return self._password[0:10] + "..." # because of security only show 1st characters

    # update password, this is conventional setter
    def set_password(self, password):
        """Create a hashed password."""
        self._password = generate_password_hash(password, method='sha256')

    # check password parameter versus stored/encrypted password
    def is_password(self, password):
        """Check against hashed password."""
        result = check_password_hash(self._password, password)
        return result
    
    # output content using str(object) in human readable form, uses getter
    def __str__(self):
        return f'name: "{self.name}", id: "{self.uid}", psw: "{self.password}"'

    # output command to recreate the object, uses attribute directly
    def __repr__(self):
        return f'Person(name={self._name}, uid={self._uid}, password={self._password})'


# tester method to print users
def tester(users, uid, psw):
    result = None
    for user in users:
        # test for match in database
        if user.uid == uid and user.is_password(psw):  # check for match
            print("* ", end="")
            result = user
        # print using __str__ method
        print(str(user))
    return result
        

# place tester code inside of special if!  This allows include without tester running
if __name__ == "__main__":

    # define user objects
    u1 = User(name='Thomas Edison', uid='toby', password='123toby')
    u2 = User(name='Nicholas Tesla', uid='nick', password='123nick')
    u3 = User(name='Alexander Graham Bell', uid='lex', password='123lex')
    u4 = User(name='Eli Whitney', uid='eli', password='123eli')
    u5 = User(name='Hedy Lemarr', uid='hedy', password='123hedy')

    # put user objects in list for convenience
    users = [u1, u2, u3, u4, u5]

    # Find user
    print("Test 1, find user 3")
    u = tester(users, u3.uid, "123lex")


    # Change user
    print("Test 2, change user 3")
    u.name = "John Mortensen"
    u.uid = "jm1021"
    u.set_password("123qwerty")
    u = tester(users, u.uid, "123qwerty")


    # Make dictionary
    ''' 
    The __dict__ in Python represents a dictionary or any mapping object that is used to store the attributes of the object. 
    Every object in Python has an attribute that is denoted by __dict__. 
    Use the json.dumps() method to convert the list of Users to a JSON string.
    '''
    print("Test 3, make a dictionary")
    json_string = json.dumps([user.__dict__ for user in users]) 
    print(json_string)

    print("Test 4, make a dictionary")
    json_string = json.dumps([vars(user) for user in users]) 
    print(json_string)
Test 1, find user 3
name: "Thomas Edison", id: "toby", psw: "sha256$gQH..."
name: "Nicholas Tesla", id: "nick", psw: "sha256$KjX..."
* name: "Alexander Graham Bell", id: "lex", psw: "sha256$7IB..."
name: "Eli Whitney", id: "eli", psw: "sha256$aVC..."
name: "Hedy Lemarr", id: "hedy", psw: "sha256$jYV..."
Test 2, change user 3
name: "Thomas Edison", id: "toby", psw: "sha256$gQH..."
name: "Nicholas Tesla", id: "nick", psw: "sha256$KjX..."
* name: "John Mortensen", id: "jm1021", psw: "sha256$cge..."
name: "Eli Whitney", id: "eli", psw: "sha256$aVC..."
name: "Hedy Lemarr", id: "hedy", psw: "sha256$jYV..."
Test 3, make a dictionary
[{"_name": "Thomas Edison", "_uid": "toby", "_password": "sha256$gQHRKXLozaGT5MF3$e861a1aa55324f791703f4f9305ce689093428340faff392514c1117aa554058"}, {"_name": "Nicholas Tesla", "_uid": "nick", "_password": "sha256$KjX5Jbzna7M9kw1L$602c1cd2719003068e7fb1cce87049db2c9f84820ce173d990e9db4f3f2cd4e9"}, {"_name": "John Mortensen", "_uid": "jm1021", "_password": "sha256$cgeOudVobFNPF8T5$a3ed794095f064de9cddcbeb890c00976ac28dd87e892d3ee471d5ae427c9825"}, {"_name": "Eli Whitney", "_uid": "eli", "_password": "sha256$aVCOZcqcKpMP0veE$b5f556490fc1ee6451a2771e3f7fed453f502e2b8696b5ee64eacc9b60d6a486"}, {"_name": "Hedy Lemarr", "_uid": "hedy", "_password": "sha256$jYVAuGL3vLZ9JXdX$b103a5d4f29e837092c41145e09d0bba2c3fe129c49d7c122a08bef1a9fe3362"}]
Test 4, make a dictionary
[{"_name": "Thomas Edison", "_uid": "toby", "_password": "sha256$gQHRKXLozaGT5MF3$e861a1aa55324f791703f4f9305ce689093428340faff392514c1117aa554058"}, {"_name": "Nicholas Tesla", "_uid": "nick", "_password": "sha256$KjX5Jbzna7M9kw1L$602c1cd2719003068e7fb1cce87049db2c9f84820ce173d990e9db4f3f2cd4e9"}, {"_name": "John Mortensen", "_uid": "jm1021", "_password": "sha256$cgeOudVobFNPF8T5$a3ed794095f064de9cddcbeb890c00976ac28dd87e892d3ee471d5ae427c9825"}, {"_name": "Eli Whitney", "_uid": "eli", "_password": "sha256$aVCOZcqcKpMP0veE$b5f556490fc1ee6451a2771e3f7fed453f502e2b8696b5ee64eacc9b60d6a486"}, {"_name": "Hedy Lemarr", "_uid": "hedy", "_password": "sha256$jYVAuGL3vLZ9JXdX$b103a5d4f29e837092c41145e09d0bba2c3fe129c49d7c122a08bef1a9fe3362"}]

Hacks

Add new attributes/variables to the Class. Make class specific to your CPT work.

  • Add classOf attribute to define year of graduation
    • Add setter and getter for classOf
  • Add dob attribute to define date of birth
    • This will require investigation into Python datetime objects as shown in example code below
    • Add setter and getter for dob
  • Add instance variable for age, make sure if dob changes age changes
    • Add getter for age, but don't add/allow setter for age
  • Update and format tester function to work with changes

Start a class design for each of your own Full Stack CPT sections of your project

  • Use new code cell in this notebook
  • Define init and self attributes
  • Define setters and getters
  • Make a tester

Start Code for Hacks

from datetime import date

def calculate_age(born):
    today = date.today()
    return today.year - born.year - ((today.month, today.day) < (born.month, born.day))

dob = date(2004, 12, 31)
age = calculate_age(dob)
print(age)
from werkzeug.security import generate_password_hash, check_password_hash
from datetime import date
import json

class User:    

    def __init__(self, name, uid, password, dob, classOf):
        self._name = name    # variables with self prefix become part of the object, 
        self._uid = uid
        self.set_password(password)
        self._dob = dob
        self._classOf = classOf
    
    @property
    def name(self):
        return self._name
    
    # a setter function, allows name to be updated after initial object creation
    @name.setter
    def name(self, name):
        self._name = name
    
    # a getter method, extracts email from object
    @property
    def uid(self):
        return self._uid
    
    # a setter function, allows name to be updated after initial object creation
    @uid.setter
    def uid(self, uid):
        self._uid = uid
        
    # check if uid parameter matches user id in object, return boolean
    def is_uid(self, uid):
        return self._uid == uid
    
    # dob property is returned as string, to avoid unfriendly outcomes
    @property
    def dob(self):
        dob_string = self._dob.strftime('%m-%d-%Y')
        return dob_string
    
    # dob should be have verification for type date
    @dob.setter
    def dob(self, dob):
        self._dob = dob
        
    # age is calculated and returned each time it is accessed
    @property
    def age(self):
        today = date.today()
        return today.year - self._dob.year - ((today.month, today.day) < (self._dob.month, self._dob.day))

    @property
    def classOf(self):
        return self._classOf
    
    # a setter function, allows name to be updated after initial object creation
    @classOf.setter
    def classOf(self, classOf):
        self._classOf = classOf
    
    # dictionary is customized, removing password for security purposes
    @property
    def dictionary(self):
        dict = {
            "name" : self.name,
            "uid" : self.uid,
            "dob" : self.dob,
            "age" : self.age,
            "classOf" : self.classOf
        }
        return dict
    
    # update password, this is conventional setter
    def set_password(self, password):
        """Create a hashed password."""
        self._password = generate_password_hash(password, method='sha256')

    # check password parameter versus stored/encrypted password
    def is_password(self, password):
        """Check against hashed password."""
        result = check_password_hash(self._password, password)
        return result
    
    # output content using json dumps, this is ready for API response
    def __str__(self):
        return json.dumps(self.dictionary)
    
    # output command to recreate the object, uses attribute directly
    def __repr__(self):
        return f'User(name={self._name}, uid={self._uid}, password={self._password},dob={self._dob}, classOf={self._classOf})'

def tester(users, uid, psw):
    result = None
    for user in users:
        # test for match in database
        if user.uid == uid and user.is_password(psw):  # check for match
            print("* ", end="")
            result = user
        # print using __str__ method
        print(str(user))
    return result    

if __name__ == "__main__":
    u1 = User(name='Dylan OBrien', uid='mazerunner', password='success', dob=date(1999, 2, 11), classOf='1920')
    u2 = User(name='Ava Carlson', uid='coolcat', password='welovecoolcats4', dob=date(2006, 1, 13), classOf='2024')
    u3 = User(name='Tom Holland', uid='thebestspiderman', password='peter1', dob=date(1999, 8, 12), classOf='2015')


    # put user objects in list for convenience
    users = [u1, u2, u3]

    # Find user
    print("Test 1, find user 3")
    u = tester(users, u3.uid, "peter1")

    # Change user
    print("Test 2, change user 3")
    u.name = "John Mortensen"
    u.uid = "jm1021"
    u.set_password("123qwerty")
    u = tester(users, u.uid, "123qwerty")

    
print("JSON ready string:\n", u2, "\n") 
print("Raw Variables of object:\n", vars(u2), "\n") 
print("Raw Attributes and Methods of object:\n", dir(u2), "\n")
print("Representation to Re-Create the object:\n", repr(u2), "\n")
Test 1, find user 3
{"name": "Dylan OBrien", "uid": "mazerunner", "dob": "02-11-1999", "age": 23, "classOf": "1920"}
{"name": "Ava Carlson", "uid": "coolcat", "dob": "01-13-2006", "age": 17, "classOf": "2024"}
* {"name": "Tom Holland", "uid": "thebestspiderman", "dob": "08-12-1999", "age": 23, "classOf": "2015"}
Test 2, change user 3
{"name": "Dylan OBrien", "uid": "mazerunner", "dob": "02-11-1999", "age": 23, "classOf": "1920"}
{"name": "Ava Carlson", "uid": "coolcat", "dob": "01-13-2006", "age": 17, "classOf": "2024"}
* {"name": "John Mortensen", "uid": "jm1021", "dob": "08-12-1999", "age": 23, "classOf": "2015"}
JSON ready string:
 {"name": "Ava Carlson", "uid": "coolcat", "dob": "01-13-2006", "age": 17, "classOf": "2024"} 

Raw Variables of object:
 {'_name': 'Ava Carlson', '_uid': 'coolcat', '_password': 'sha256$7Bxy8S38fzctiLgy$58d1a97d9d59092d5786d75125d13ec992c00cd1a358bbd515f74df34acedb18', '_dob': datetime.date(2006, 1, 13), '_classOf': '2024'} 

Raw Attributes and Methods of object:
 ['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_classOf', '_dob', '_name', '_password', '_uid', 'age', 'classOf', 'dictionary', 'dob', 'is_password', 'is_uid', 'name', 'set_password', 'uid'] 

Representation to Re-Create the object:
 User(name=Ava Carlson, uid=coolcat, password=sha256$7Bxy8S38fzctiLgy$58d1a97d9d59092d5786d75125d13ec992c00cd1a358bbd515f74df34acedb18,dob=2006-01-13, classOf=2024) 

For Team Project:

from werkzeug.security import generate_password_hash, check_password_hash
import json

class User:    

    def __init__(self, name, uid, password, workouts):
        self._name = name    # variables with self prefix become part of the object, 
        self._uid = uid
        self.set_password(password)
        self._workouts = workouts
    
    @property
    def name(self):
        return self._name
    
    # a setter function, allows name to be updated after initial object creation
    @name.setter
    def name(self, name):
        self._name = name
    
    # a getter method, extracts email from object
    @property
    def uid(self):
        return self._uid
    
    # a setter function, allows name to be updated after initial object creation
    @uid.setter
    def uid(self, uid):
        self._uid = uid
        
    # check if uid parameter matches user id in object, return boolean
    def is_uid(self, uid):
        return self._uid == uid
    
    
    @property
    def workouts(self):
        return self._workouts
    
    # a setter function, allows name to be updated after initial object creation
    @workouts.setter
    def workouts(self, workouts):
        self._workouts = workouts

    
    
    # dictionary is customized, removing password for security purposes
    @property
    def dictionary(self):
        dict = {
            "name" : self.name,
            "uid" : self.uid,
            "workouts" : self.workouts
        }
        return dict
    
    # update password, this is conventional setter
    def set_password(self, password):
        """Create a hashed password."""
        self._password = generate_password_hash(password, method='sha256')

    # check password parameter versus stored/encrypted password
    def is_password(self, password):
        """Check against hashed password."""
        result = check_password_hash(self._password, password)
        return result
    
    # output content using json dumps, this is ready for API response
    def __str__(self):
        return json.dumps(self.dictionary)
    
    # output command to recreate the object, uses attribute directly
    def __repr__(self):
        return f'User(name={self._name}, uid={self._uid}, password={self._password}, workouts={self._workouts})'
        
def tester(users, uid, psw):
    result = None
    for user in users:
        # test for match in database
        if user.uid == uid and user.is_password(psw): # check for match
            print("* ", end="")
            result = user
        # print using __str__ method
        print(str(user))
    return result    

if __name__ == "__main__":
    u1 = User(name='Thomas Edison', uid='toby', password='123toby', workouts='burpees, swimming')
    u2 = User(name='Ava Carlson', uid='coolcat', password='welovecoolcats4', workouts='sprinting, cheer')
    u3 = User(name='Tom Holland', uid='thebestspiderman', password='peter1', workouts='climbing, boxing')

    # put user objects in list for convenience
    users = [u1, u2, u3]

    # Find user
    print("Test 1, find user 3")
    u = tester(users, u3.uid, "peter1")

    # Change user
    print("Test 2, change user 3")
    u.name = "Andrew Garfield"
    u.uid = "spidermanalso"
    u.workouts = "punching"
    u.set_password("peter3")
    u = tester(users, u.uid, "peter3")




    print("JSON ready string:\n", u1, "\n") 
    print("Raw Variables of object:\n", vars(u1), "\n") 
    print("Raw Attributes and Methods of object:\n", dir(u1), "\n")
    print("Representation to Re-Create the object:\n", repr(u1), "\n") 

    print("JSON ready string:\n", u2, "\n") 
    print("Raw Variables of object:\n", vars(u2), "\n") 
    print("Raw Attributes and Methods of object:\n", dir(u2), "\n")
    print("Representation to Re-Create the object:\n", repr(u2), "\n") 
Test 1, find user 3
{"name": "Thomas Edison", "uid": "toby", "workouts": "burpees, swimming"}
{"name": "Ava Carlson", "uid": "coolcat", "workouts": "sprinting, cheer"}
* {"name": "Tom Holland", "uid": "thebestspiderman", "workouts": "climbing, boxing"}
Test 2, change user 3
{"name": "Thomas Edison", "uid": "toby", "workouts": "burpees, swimming"}
{"name": "Ava Carlson", "uid": "coolcat", "workouts": "sprinting, cheer"}
* {"name": "Andrew Garfield", "uid": "spidermanalso", "workouts": "punching"}
JSON ready string:
 {"name": "Thomas Edison", "uid": "toby", "workouts": "burpees, swimming"} 

Raw Variables of object:
 {'_name': 'Thomas Edison', '_uid': 'toby', '_password': 'sha256$N3Fh0b1UYfuXkvdm$d79a061aefd539fcc674fe1c2e9076e91554c03efef92cdce92d7bae8dce3f98', '_workouts': 'burpees, swimming'} 

Raw Attributes and Methods of object:
 ['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_name', '_password', '_uid', '_workouts', 'dictionary', 'is_password', 'is_uid', 'name', 'set_password', 'uid', 'workouts'] 

Representation to Re-Create the object:
 User(name=Thomas Edison, uid=toby, password=sha256$N3Fh0b1UYfuXkvdm$d79a061aefd539fcc674fe1c2e9076e91554c03efef92cdce92d7bae8dce3f98, workouts=burpees, swimming) 

JSON ready string:
 {"name": "Ava Carlson", "uid": "coolcat", "workouts": "sprinting, cheer"} 

Raw Variables of object:
 {'_name': 'Ava Carlson', '_uid': 'coolcat', '_password': 'sha256$F3jSUrNDGCs82iFR$3fc50486c6a0262e5e4b5bdb639080dab2036412fc57b7cbfcb3f8fad34226d8', '_workouts': 'sprinting, cheer'} 

Raw Attributes and Methods of object:
 ['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', '_name', '_password', '_uid', '_workouts', 'dictionary', 'is_password', 'is_uid', 'name', 'set_password', 'uid', 'workouts'] 

Representation to Re-Create the object:
 User(name=Ava Carlson, uid=coolcat, password=sha256$F3jSUrNDGCs82iFR$3fc50486c6a0262e5e4b5bdb639080dab2036412fc57b7cbfcb3f8fad34226d8, workouts=sprinting, cheer)