Flask-WTF for form validation - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Flask-WTF used for in a Flask application?

Flask-WTF is used to simplify form creation and validation in Flask apps. It helps handle user input safely and easily.

beginner

How do you define a form field in Flask-WTF?

You define a form field by creating a class that inherits from FlaskForm and adding fields like StringField or PasswordField with validators.

beginner

What is the purpose of validators in Flask-WTF?

Validators check if the user input meets rules like required fields or correct email format before processing the form.

intermediate

How do you protect a Flask-WTF form from CSRF attacks?

Flask-WTF automatically adds a hidden CSRF token field to forms to protect against CSRF attacks, ensuring the form is submitted from your site.

beginner

What method do you call to check if a Flask-WTF form is valid after submission?

You call the form's validate_on_submit() method, which returns True if the form was submitted and all validations passed.

Which class should your form class inherit from when using Flask-WTF?

A Form

B FlaskForm

C BaseForm

D WTForm

Flask-WTF requires your form class to inherit from FlaskForm to get all the features like CSRF protection and validation.

What does the DataRequired validator do in Flask-WTF?

A Ensures the field is not empty

B Checks if input is a valid email

C Limits input length

D Validates password strength

DataRequired makes sure the user enters some data in the field; it cannot be left blank.

How do you access form data after validation in Flask-WTF?

A Using form.get_data()

B Using request.form['fieldname']

C Using form.fieldname.data

D Using form.input_value()

After validation, you get the cleaned data from form fields using form.fieldname.data.

Which method checks if the form was submitted and is valid in Flask-WTF?

A validate_on_submit()

B is_valid()

C check_form()

D submit_valid()

validate_on_submit() returns True if the form was submitted via POST and all validators pass.

What built-in feature does Flask-WTF provide to prevent CSRF attacks?

A Session timeout

B Password hashing

C Input sanitization

D CSRF token hidden field

Flask-WTF adds a hidden CSRF token field to forms to protect against cross-site request forgery.

Explain how to create and validate a simple login form using Flask-WTF.

Think about the steps from defining the form to checking if user input is valid.

Describe how Flask-WTF helps protect your web forms from security risks.

Focus on the security features built into Flask-WTF.