Applikationsutveckling för webben

Instuderingsfrågor

• What is URL mapping in Flask?
  URL mapping in Flask is the process of linking URLs to the functions that should handle those URLs. This is done using the @app.route decorator.
• How do you define a route in Flask?
  A route in Flask is defined using the @app.route decorator. For example:
  @app.route('/')
  def home():
  return 'Hello, World!'
• How can you create a route that accepts both GET and POST methods?
  You can specify the methods in the methods parameter of the @app.route decorator. For example:
  @app.route('/submit', methods=['GET', 'POST'])
• What is the purpose of the url_for function in Flask?
  The url_for function is used to generate URLs for the routes defined in the Flask application. It is useful for creating links and redirecting users to different parts of the application. For example:
  url_for('home')
• How do you define a route with a dynamic variable in Flask?
  You define a route with a dynamic variable by including it in the URL string within angle brackets.
• What is the purpose of using dynamic variables in routes?
  Dynamic variables allow you to create flexible and dynamic URLs that can capture and process different types of user input, making your application more interactive and capable of handling a variety of requests.
• What is a template in Flask?
  A template in Flask is an HTML file that contains placeholders for dynamic content. Templates are used to generate HTML dynamically by combining static HTML with data passed from the Flask application.
• How do you render a template in Flask?
  You render a template in Flask using the render_template function. For example:
  @app.route('/hello')
  def hello():
  return render_template('hello.html')
• What is Jinja2 in Flask
  Jinja2 is the default templating engine for Flask. It allows you to use Python-like expressions inside your HTML templates to dynamically generate content.
• What is a Blueprint in Flask?
  A Blueprint in Flask is a way to organize and structure your application into smaller, reusable components. Blueprints allow you to define routes, templates, static files, and other application components separately and then register them with the main application.
• How do you create a Blueprint in Flask?
  You create a Blueprint by instantiating the Blueprint class and defining routes on it. For example:
  from flask import Blueprint
  bp = Blueprint('bp', __name__)
  @bp.route('/hello')
  def hello():
  return 'Hello from the blueprint!'
• How do you register a Blueprint with the main Flask application?
  You register a Blueprint with the main Flask application using the app.register_blueprint method. For example:
  from flask import Flask
  from my_blueprint import bp
  app = Flask(__name__)
  app.register_blueprint(bp, url_prefix='/blueprint')
• What is a session in Flask?
  A session in Flask is a way to store information about a user across multiple requests. It is a dictionary that can hold data specific to a user.
• How do you set up a session in Flask?
  To set up a session in Flask, you need to configure a secret key for the application. For example:
  app = Flask(__name__)
  app.config['SECRET_KEY'] = 'your_secret_key'
• How do you store data in a session in Flask?
  from flask import session
  @app.route('/set_session')
  def set_session():
  session['username'] = 'JohnDoe'
  return 'Session data set'
• How do you retrieve data from a session in Flask?
  @app.route('/get_session')
  def get_session():
  username = session.get('username', 'Guest')
  return f'Hello, {username}!'

Instuderingsfrågor

• How do you handle form submission in Flask?
  You handle form submission by creating a route that listens for POST requests. For example:
  @app.route('/submit', methods=['POST'])
  def submit():
  name = request.form['name']
• What library can you use for form validation in Flask?
  You can use the WTForms library for form validation in Flask.
• How do you create a form class using WTForms?
  You create a form class by inheriting from FlaskForm and defining form fields as class attributes. For example:
  from flask_wtf import FlaskForm from wtforms import StringField
  from wtforms.validators import DataRequired
  class MyForm(FlaskForm):
  name = StringField('Name', validators=[DataRequired()])
• How do you render a WTForms form in a Flask template?
  You render a WTForms form using Jinja2 syntax in the template html form, for example: {{ form.hidden_tag() }} {{ form.name.label }} {{ form.name(size=20) }}
• What is CSRF protection and why is it important?
  CSRF (Cross-Site Request Forgery) protection prevents unauthorized commands from being transmitted from a user that the web application trusts. It is important to prevent malicious exploits and secure user data.
• How do you include CSRF tokens in your forms?
  WTForms automatically includes CSRF tokens in your forms when using form.hidden_tag(). Ensure your form class inherits from FlaskForm.
• How do you display form validation errors in a Flask template?
  You display form validation errors by iterating over the form.errors dictionary in your template. For example:
  {% for field, errors in form.errors.items() %}
  {% for error in errors %}
  {{ error }}
  {% endfor %}
  {% endfor %}

Instuderingsfrågor

• How do you connect to an SQLite database using the sqlite3 library in Flask?
  You connect to an SQLite database using the sqlite3.connect() method. For example:
  import sqlite3
  conn = sqlite3.connect('database.db')
• How do you create a table in an SQLite database using sqlite3?
  You create a table by executing a SQL CREATE TABLE statement. For example:
  conn.execute('CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT, email TEXT)')
  conn.commit()
• How do you insert data into an SQLite table using sqlite3?
  You insert data by executing an INSERT INTO statement. For example:
  conn.execute('INSERT INTO users (name, email) VALUES (?, ?)', ('John Doe', 'john@example.com'))
  conn.commit()
• How do you retrieve data from an SQLite table using sqlite3?
  You retrieve data by executing a SELECT statement and fetching the results. For example:
  cursor = conn.execute('SELECT * FROM users')
  for row in cursor:
  print(row)
• How do you update data in an SQLite table using sqlite3?
  You delete data by executing a DELETE statement. For example:
  conn.execute('DELETE FROM users WHERE name = ?', ('John Doe',))
  conn.commit()
• How do you close a database connection in sqlite3?
  You close a database connection using the close() method.
• What is SQLAlchemy?
  SQLAlchemy is a SQL toolkit and Object-Relational Mapping (ORM) library for Python.

Instuderingsfrågor