Solutions for 10, lesson 11

lesson_10/SOLUTION_EXERCISE_10.md

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+# Exercise Lesson 10
+
+## Instructions
+
+Todays exercises goal is to practice more on object oriented programming
+
+### `Exercise 1` override
+
+1. Create a class that has at least one method
+
+    ```python
+    class Bicycle:
+
+        def __init__(self):
+            self.speed = 2
+
+        def accelerate(self):
+            self.speed += 1
+
+        def slow(self):
+            self.speed -= 1
+    ```
+
+2. Create a subclass that uses your class (1) as base class
+
+    ```python
+    class MTB(Bicycle):
+        pass
+    ```
+
+3. In the subclass (2) you should override the method from (1)
+
+    ```python
+    class MTB(Bicycle):
+
+        def slow(self):
+            self.speed -= 1.2
+    ```
+
+4. Print a instance of (1) and (2) both calling the same method name
+
+    ```python
+    bicycle = Bicycle()
+    bicycle.slow()
+    print(bicycle.speed)
+
+    mtb = MTB()
+    mtb.slow()
+    print(mtb.speed)
+    ```
+
+<div class="page"/>
+
+### `Exercise 2` menu
+
+1. Create a class, i.e `Dog`, `Animal`, `Fridge`
+2. Create a program that uses a menu
+   1. The first option will create an object from your class
+   2. The second option will print the object
+   3. The third option will delete the object
+3. If you try to print before creating an object or after deleted it, the program should print `No object available to print`
+4. If you try to delete a object that doesn't exist, the program should print `No object to delete`
+
+    ```python
+
+    class Dog:
+        def __init__(self):
+            self.food = 0
+
+        def eat(self):
+            self.food += 1
+
+        def __str__(self):
+            return f"I'm your best friend and my food level is ${self.food}"
+
+    class Dog:
+        def __init__(self):
+            self.food = 0
+
+        def eat(self):
+            self.food += 1
+
+        def __str__(self):
+            return f"I'm your best friend and my food level is ${self.food}"
+
+    class Menu:
+
+        MAIN_MENU_TEXT = """
+        Welcome to this program!
+
+        1. Create a new object
+        2. Print your object
+        3. Delete your object
+
+        type q or Q to delete
+        """
+
+        def user_choice(self):
+            return input("Enter your choice 1-3 or q: ")
+
+        def wait_for_user(self):
+            if self.running:
+                input("Please press any key to continues.")
+
+        def menu_commands(self, choice):
+            if choice == 'q' or choice == 'Q':
+                self.running = False
+            elif choice == "1":
+                self.dog = Dog()
+            elif choice == "2":
+                try:
+                    print(self.dog)
+                except AttributeError:
+                    print("No object available to print")
+            elif choice == "3":
+                try:
+                    del self.dog
+                except AttributeError:
+                    print("No object to delete")
+                    # Alternative self.dog = None
+
+        def start_loop(self):
+            self.running = True
+            while self.running:
+                print(Menu.MAIN_MENU_TEXT)
+                choice = self.user_choice()
+                self.menu_commands(choice)
+                self.wait_for_user()
+
+    Menu().start_loop()
+    ```
+
+<div class="page"/>
+
+## `Exercise 3` composition vs inheritance
+
+In this exercise you will write two alternative solutions, one with inheritance and one with composition.
+
+### Inheritance
+
+1. Create a class named `Person`, it should have `address` stored, with street name, street number, postal code, country.
+
+2. Create a class `Employee` that uses `Person´ as base class. Add employee number and salary.
+
+    ```python
+    class Person:
+        def __init__(self, street_name, postal_code, country):
+            self.street_name = street_name
+            self.postal_code = postal_code
+            self.country = country
+
+
+    class Employee(Person):
+        def __init__(self, street_name, postal_code, country, emp_number, salary):
+            super().__init__(street_name, postal_code, country)
+            self.emp_number = emp_number
+            self.salary = salary
+
+        def __str__(self):
+            return f"emp {self.emp_number} live on {self.street_name}"
+
+
+    emp = Employee("Sveavägen", "11350", "Sweden", 1, 10000)
+    print(emp)
+    ```
+
+<div class="page"/>
+
+### Composition
+
+1. Create a class `Address` with street name, street number, postal code, country.
+2. Create a class `Employee` that has an address class, employee number and salary
+
+    ```python
+    class Address:
+        def __init__(self, street_name, postal_code, country):
+            self.street_name = street_name
+            self.postal_code = postal_code
+            self.country = country
+
+
+    class Employee:
+        def __init__(self, address, emp_number, salary):
+            self.address = address
+            self.emp_number = emp_number
+            self.salary = salary
+
+        def __str__(self):
+            return f"emp {self.emp_number} live on {self.address.street_name}"
+
+
+    address = Address("Sveavägen", "11350", "Sweden")
+    emp = Employee(address, 1, 10000)
+    print(emp)
+    ```

lesson_11/EXERCISE_11.md

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+# Group Exercise Lesson 11
+
+## Instructions
+
+This is probably your first slightly larger program, so you will tackle it as a group exercise. Each team consists of 3-4 members. You can write your program fully object-oriented or not, this is up to your team to decide. The only requirement is that you somewhere use a class `Person`.
+
+### `Exercise 1` Load data from a file
+
+1. Create a file in either csv or json format (your choice). It should contain data for at least 5 Persons, you can create it manually or with a script.
+2. A person has a firstname, lastname, birthdate and address.
+3. Let the user enter the path to the file
+4. Read the file and insert it into a SQLite database you have created.
+
+### `Exercise 2` List all persons stored in the database
+
+*Hint* here is a good place to use the class `Person`. e.g you can create a Person object for each row, and print it with a custom `__str__` method.
+
+1. Create a (SQL) query that gets all rows (select *) from the table
+2. Print all rows
+
+### `Exercise 3` Menu
+
+1. Create a menu with options:
+   1. Load data from file (Use your solution from Exercise 1)
+   2. List all persons (select *) (Use your solution from Exercise 2)
+      1. EXTRA let the user type a firstname and query the database with that firstname
+      2. EXTRA let the user type a lastname and query the database with that lastname
+      3. EXTRA let the user type a birthdate and query query the database with that birthdate
+      4. EXTRA let the user type an address and query the database with that address
+   3. Delete a person
+   4. EXTRA update a persons address with input from the user
+
+### EXTRA EXTRA Add another table
+
+Create another table, i.e Vehicles, Friends or Transactions. Make sure the content
+would have some relation to Persons defined in the other table, e.g. a vehicle is owned
+by a person or a transaction was done by a person.
+
+1. Add it to your menu
+2. Make it possible to add data to the second table
+3. Query the database with a join between Person table and your second table, so you can see the combined results.

lesson_11/LINKS_11.md

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+# Links
+
+## Sql
+
+- Python docs a lightweight disk-based database [sqlite3](https://docs.python.org/3/library/sqlite3.html)
+- SQLite extension for Visual Studio Code [vscode-sqlite](https://marketplace.visualstudio.com/items?itemName=alexcvzz.vscode-sqlite)
+- Sql [create db](https://www.w3schools.com/sql/sql_create_db.asp)
+- Sql [create table](https://www.w3schools.com/sql/sql_create_table.asp)
+- Sql [insert into](https://www.w3schools.com/sql/sql_insert.asp)
+- Sql [select](https://www.w3schools.com/sql/sql_select.asp)
+- Sql [delete](https://www.w3schools.com/sql/sql_delete.asp)
+
+## Sql Extra
+
+- Sql [update](https://www.w3schools.com/sql/sql_update.asp)
+- Sql [where](https://www.w3schools.com/sql/sql_where.asp)
+- Sql tables [join](https://www.w3schools.com/sql/sql_join.asp)
+
+## Python
+
+- Python docs about file format [csv](https://docs.python.org/3/library/csv.html)
+- Python docs about file format [json](https://docs.python.org/3/library/json.html)
+
+## Git
+
+- Git [cheat sheet](https://education.github.com/git-cheat-sheet-education.pdf)

lesson_11/examples/10_file.py

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+try:
+    with open("a_lost_file", "r") as f:
+        print(f)
+except FileNotFoundError:
+    print("File not found")

lesson_11/examples/11_extra_sql.py

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+import sqlite3
+from tabulate import tabulate
+
+try:
+    with sqlite3.connect(':memory:', isolation_level=None) as conn:
+        conn.execute(
+            """
+            CREATE TABLE customers (
+                id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
+                firstname TEXT,
+                lastname TEXT
+            )
+            """)
+
+        conn.execute(
+            """
+            CREATE TABLE orders (
+                id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
+                customer_id INTEGER NOT NULL,
+                status TEXT
+            )
+            """)
+
+        conn.executemany(
+            """
+            INSERT INTO customers (
+                firstname,
+                lastname
+            ) VALUES(?, ?)
+            """, (("Nils", "Smith"), ("Adam", "Williams"), ("Joe", "Clinton")))
+
+        conn.executemany(
+            """
+            INSERT INTO orders (
+                customer_id,
+                status
+            ) VALUES(?, ?)
+            """, ((1, "shipped"), (1, "prepared"), (2, "cancelled")))
+
+        customer_orders = conn.execute(
+            """
+            SELECT o.id as order_id, c.id as customer_id, c.firstname, c.lastname, o.status
+            FROM orders AS o
+            INNER JOIN customers AS c ON o.customer_id=c.id
+            """
+        )
+
+        description = tuple(map(lambda x: x[0], customer_orders.description))
+        print(tabulate(customer_orders.fetchall(), description))
+
+except Exception as e:
+    print(e)
+finally:
+    conn.close()

lesson_11/examples/1_generate_csv.py

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+import csv
+
+cars = [
+    {
+        "Manufacturer": "Tesla",
+        "Model": "Model 3",
+        "Year": "2019",
+        "Price": "523800"
+    },
+    {
+        "Manufacturer": "Volvo",
+        "Model": "XC60",
+        "Year": "2018",
+        "Price": "313000"
+    },
+    {
+        "Manufacturer": "Saab",
+        "Model": "900",
+        "Year": "1994",
+        "Price": "3000"
+    }
+]
+
+# https://docs.python.org/3/library/csv.html
+with open('lesson_11/examples/data/cars.csv', 'w') as f:
+    csv_writer = csv.DictWriter(f, fieldnames=cars[0].keys())
+    csv_writer.writeheader()
+    csv_writer.writerows(cars)

lesson_11/examples/2_generate_json.py

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+import json
+
+persons = {
+    "persons": [{
+        "firstname": "pelle",
+        "lastname": "svensson",
+        "year_of_birth": 1994
+    },
+        {
+        "firstname": "olle",
+            "lastname": "svensson",
+            "year_of_birth": 1943
+    },
+        {
+        "firstname": "nisse",
+            "lastname": "svensson",
+            "year_of_birth": 1967
+    }
+    ]
+
+}
+
+# https://docs.python.org/3/library/json.html
+with open('lesson_11/examples/data/persons.json', 'w') as f:
+    f.write(json.dumps(persons, indent=4))

lesson_11/examples/3_read_csv.py

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+import csv
+
+with open("lesson_11/examples/data/cars.csv") as f:
+    reader = csv.reader(f)
+    for row in reader:
+        print(row)

lesson_11/examples/4_read_json.py

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+import json
+
+with open("lesson_11/examples/data/persons.json") as f:
+    cars = json.load(f)
+    print(cars)