User model with password in Flask - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the password hashing function.

Flask

from werkzeug.security import [1]

Drag options to blanks, or click blank then click option'

Agenerate_password_hash

Bhash_password

Ccheck_password_hash

Dpassword_hash

Attempts:

3 left

💡 Hint

Common Mistakes

Using check_password_hash instead of generate_password_hash

Trying to import a non-existent function like hash_password

The generate_password_hash function is used to create a hashed password for security.

2fill in blank

medium

Complete the code to define the password field in the User model.

Flask

password_hash = db.Column(db.[1](128), nullable=False)

Drag options to blanks, or click blank then click option'

AInteger

BString

CText

DBoolean

Attempts:

3 left

💡 Hint

Common Mistakes

Using Integer or Boolean types for password hash

Using Text which allows unlimited length but is less common here

The password hash is stored as a string with a max length, so String is the correct column type.

3fill in blank

hard

Fix the error in the method that sets the password hash.

Flask

def set_password(self, password):
    self.password_hash = [1](password)

Drag options to blanks, or click blank then click option'

Acheck_password_hash

Bhash_password

Cpassword_hash

Dgenerate_password_hash

Attempts:

3 left

💡 Hint

Common Mistakes

Using check_password_hash instead of generate_password_hash

Trying to assign the password string directly

The generate_password_hash function creates a secure hash from the password string.

4fill in blank

hard

Fill both blanks to complete the method that verifies a password.

Flask

def check_password(self, password):
    return [1](self.password_hash, [2])

Drag options to blanks, or click blank then click option'

Acheck_password_hash

Bpassword

Cgenerate_password_hash

Dself.password

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the order of arguments

Using generate_password_hash instead of check_password_hash

The check_password_hash function compares the stored hash with the given password string.

5fill in blank

hard

Fill all three blanks to complete the User model with password methods.

Flask

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(64), unique=True, nullable=False)
    password_hash = db.Column(db.String(128), nullable=False)

    def set_password(self, password):
        self.password_hash = [1](password)

    def check_password(self, password):
        return [2](self.password_hash, [3])

Drag options to blanks, or click blank then click option'

Agenerate_password_hash

Bpassword

Ccheck_password_hash

Dhash_password

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up generate_password_hash and check_password_hash

Passing the wrong argument to check_password_hash

The set_password method uses generate_password_hash to create the hash. The check_password method uses check_password_hash to verify the password against the stored hash.

Practice

1. What is the main purpose of the set_password method in a Flask user model?

easy

A. To delete the user's password from the database

B. To hash and store the user's password securely

C. To check if the password entered matches the stored password

D. To display the user's password in plain text

Solution

1. Step 1: Understand the role of set_password

   This method is used to convert a plain password into a secure hashed version before saving it.

2. Step 2: Differentiate from check_password

   check_password is for verifying passwords, not setting them.

3. Final Answer:

   To hash and store the user's password securely -> Option B

4. Quick Check:

   set_password hashes password [OK]

Hint: Remember: set_password hashes, check_password verifies [OK]

Common Mistakes:

• Confusing set_password with check_password
• Thinking set_password shows the password
• Assuming set_password deletes passwords

2. Which of the following is the correct way to define a password hashing method in a Flask user model using Werkzeug?

easy

A. def set_password(self, password): return check_password_hash(self.password_hash, password)

B. def set_password(self, password): self.password = password

C. def set_password(self, password): self.password_hash = password

D. def set_password(self, password): self.password_hash = generate_password_hash(password)

Solution

1. Step 1: Identify correct hashing usage

   The method must use generate_password_hash to hash the password before storing.

2. Step 2: Check assignment to password_hash

   The hashed password should be saved in self.password_hash, not plain password.

3. Final Answer:

   def set_password(self, password): self.password_hash = generate_password_hash(password) -> Option D

4. Quick Check:

   Use generate_password_hash to store hashed password [OK]

Hint: Use generate_password_hash to hash passwords [OK]

Common Mistakes:

• Storing plain password instead of hashed
• Using check_password_hash inside set_password
• Assigning password to wrong attribute

3. Given this Flask user model snippet, what will user.check_password('secret') return if the password was set with user.set_password('secret')?

from werkzeug.security import generate_password_hash, check_password_hash

class User:
    def __init__(self):
        self.password_hash = ''
    def set_password(self, password):
        self.password_hash = generate_password_hash(password)
    def check_password(self, password):
        return check_password_hash(self.password_hash, password)

user = User()
user.set_password('secret')

medium

A. None

B. False

C. True

D. Raises an error

Solution

1. Step 1: Understand password setting

   The password 'secret' is hashed and stored in password_hash.

2. Step 2: Check password verification

   check_password compares the hash with 'secret' and returns True if they match.

3. Final Answer:

   True -> Option C

4. Quick Check:

   Matching password returns True [OK]

Hint: check_password returns True if password matches hash [OK]

Common Mistakes:

• Expecting False for correct password
• Thinking check_password returns the hash
• Assuming error if password matches

4. Identify the error in this Flask user model code snippet:

from werkzeug.security import generate_password_hash, check_password_hash

class User:
    def __init__(self):
        self.password_hash = None
    def set_password(self, password):
        self.password_hash = generate_password_hash(password)
    def check_password(self, password):
        return check_password_hash(password, self.password_hash)

medium

A. The order of arguments in check_password_hash is reversed

B. password_hash should be initialized as an empty string, not None

C. set_password should return the hashed password

D. The class is missing a username attribute

Solution

1. Step 1: Review check_password_hash usage

   The correct order is check_password_hash(stored_hash, password).

2. Step 2: Identify argument mistake

   The code passes password first and self.password_hash second, which is wrong.

3. Final Answer:

   The order of arguments in check_password_hash is reversed -> Option A

4. Quick Check:

   check_password_hash needs (hash, password) order [OK]

Hint: check_password_hash(hash, password) order matters [OK]

Common Mistakes:

• Swapping arguments in check_password_hash
• Initializing password_hash as None causes no error but is not best
• Expecting set_password to return a value
• Confusing missing attributes with password errors

5. You want to add a method change_password to your Flask user model that updates the password only if the old password matches. Which implementation correctly applies this logic?

hard

A. def change_password(self, old_password, new_password):
if self.check_password(old_password):
self.set_password(new_password)
return True
return False

B. def change_password(self, old_password, new_password):
self.set_password(new_password)
return True

C. def change_password(self, old_password, new_password):
if old_password == new_password:
self.set_password(new_password)
return True
return False

D. def change_password(self, old_password, new_password):
if not self.check_password(new_password):
self.set_password(old_password)
return True
return False

Solution

1. Step 1: Verify old password before changing

   The method must check if the old password matches using check_password.

2. Step 2: Update password only if old password is correct

   If the check passes, call set_password with the new password and return True; else return False.

3. Final Answer:

   def change_password(self, old_password, new_password): if self.check_password(old_password): self.set_password(new_password) return True return False -> Option A

4. Quick Check:

   Change password only if old password matches [OK]

Hint: Always verify old password before setting new one [OK]

Common Mistakes:

• Changing password without verifying old password
• Comparing old and new passwords incorrectly
• Swapping old and new passwords in checks