Solution Code to the previous section

todoapp/app.py

from flask import Flask, render_template
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgres://udacitystudios@localhost:5432/todoapp'
db = SQLAlchemy(app)

class Todo(db.Model):
  __tablename__ = 'todos'
  id = db.Column(db.Integer, primary_key=True)
  description = db.Column(db.String(), nullable=False)

  def __repr__(self):
    return f'<Todo {self.id} {self.description}>'

db.create_all()

@app.route('/')
def index():
  return render_template('index.html', data=Todo.query.all())

todoapp/templates/index.html

<html>
  <head>
    <title>Todo App</title>
  </head>
  <body>
    <ul>
      {% for d in data %}
      <li>{{ d.description }}</li>
      {% endfor %}
    </ul>
  </body>
</html>

terminal commands executed

$ create todoapp
$ FLASK_APP=app.py FLASK_DEBUG=true flask run

psql todoapp
>>> \dt
>>> \d todos
>>> INSERT INTO todos (description) VALUES ('Do a thing 1');
>>> INSERT INTO todos (description) VALUES ('Do a thing 2');
>>> INSERT INTO todos (description) VALUES ('Do a thing 3');
>>> INSERT INTO todos (description) VALUES ('Do a thing 4');
>>> select * from todos;

Model View Controller (MVC) Heading

Model View Controller (MVC)

ND004 C01 L05 04 Model View Controller (MVC)

Takeaways

MVC stands for Model-View-Controller, a common pattern for architecting web applications
Describes the 3 layers of the application we are developing

Layers

Models manage data and business logic for us. What happens inside models and database, capturing logical relationships and properties across the web app objects
Views handles display and representation logic . What the user sees (HTML, CSS, JS from the user's perspective)
Controllers : routes commands to the models and views, containing control logic . Control how commands are sent to models and views, and how models and views wound up interacting with each other.

MVC Quiz

QUIZ QUESTION: :

See if you can match each MVC layer with its description.

ANSWER CHOICES:

Description	MVC layer
The Models layer
The Views layer
The Controllers layer

SOLUTION:

Description	MVC layer
The Models layer
The Views layer
The Controllers layer

Model View Controller (MVC) Quiz

SOLUTION:

Models

Layers Quiz

QUIZ QUESTION: :

For each piece of code, match them to what application layer they correspond to

ANSWER CHOICES:

Code	Layer
Controllers
Views
Models
Data

SOLUTION:

Code	Layer
Controllers
Views
Models