Object-level permissions concept in Django - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a user has permission for a specific object.

Django

if request.user.has_perm('[1]', obj):
    # Allow access
    pass

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

Aapp.delete_model

Bapp.change_model

Capp.view_model

Dapp.add_model

Attempts:

3 left

💡 Hint

Common Mistakes

Using a permission without the app label prefix.

Checking permissions without passing the object for object-level checks.

The has_perm method checks if the user has the specified permission for the given object. Here, app.view_model is the permission to view the object.

2fill in blank

medium

Complete the code to assign object-level permission to a user.

Django

from guardian.shortcuts import assign_perm
assign_perm('[1]', user, obj)

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

Aapp.change_model

Bapp.view_model

Capp.delete_model

Dapp.add_model

Attempts:

3 left

💡 Hint

Common Mistakes

Not importing assign_perm from django-guardian.

Assigning permissions without specifying the object.

The assign_perm function from django-guardian assigns a permission to a user for a specific object. Here, app.change_model grants change permission.

3fill in blank

hard

Fix the error in the code to check object-level permission correctly.

Django

if user.has_perm('[1]'):
    # Access granted
    pass

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

Aapp.view_model, obj

Bapp.view_model

Capp.change_model

Dapp.delete_model

Attempts:

3 left

💡 Hint

Common Mistakes

Calling has_perm without the object argument for object-level permissions.

Passing the object inside the permission string.

For object-level permission checks, has_perm requires the permission string and the object as the second argument. Passing only the permission string checks global permission.

4fill in blank

hard

Fill both blanks to filter objects a user has view permission for.

Django

from guardian.shortcuts import get_objects_for_user
objects = get_objects_for_user(user, '[1]', [2]=Model)

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

Aapp.view_model

BModel

Cklass

Dobj

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect keyword argument instead of klass.

Passing an object instance instead of the model class.

get_objects_for_user returns objects of a model for which the user has the specified permission. The permission string and the model class are required arguments.

5fill in blank

hard

Fill all three blanks to remove a user's object-level permission.

Django

from guardian.shortcuts import remove_perm
remove_perm('[1]', [2], [3])

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

Aapp.change_model

Buser

Cobj

Drequest.user

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the wrong user variable like request.user when user is expected.

Not passing the object instance as the third argument.

The remove_perm function removes a specific permission from a user for a given object. You need to provide the permission string, the user, and the object.

Practice

1. What is the main purpose of object-level permissions in Django?

easy

A. To speed up database queries

B. To manage user passwords securely

C. To create new database tables automatically

D. To control access to individual data items or objects

Solution

1. Step 1: Understand what object-level permissions mean

   Object-level permissions allow control over access to specific individual objects, not just general models.

2. Step 2: Compare with other options

   Options A, B, and D relate to security, performance, or database structure, not object-level access control.

3. Final Answer:

   To control access to individual data items or objects -> Option D

4. Quick Check:

   Object-level permissions = control individual objects [OK]

Hint: Object-level means per item, not general model access [OK]

Common Mistakes:

• Confusing object-level with model-level permissions
• Thinking it manages passwords or database structure
• Assuming it improves query speed

2. Which of the following is the correct way to check object-level permission for a user in Django using django-guardian?

easy

A. user.has_perm('app.view_model', obj)

B. user.has_perm('app.view_model')

C. user.check_perm('app.view_model', obj)

D. user.can_access('app.view_model', obj)

Solution

1. Step 1: Recall django-guardian permission check syntax

   django-guardian extends Django's has_perm method to accept an object as a second argument for object-level checks.

2. Step 2: Analyze options

   user.has_perm('app.view_model', obj) uses has_perm with object, which is correct. user.has_perm('app.view_model') lacks object, so it's model-level. Options C and D use incorrect method names.

3. Final Answer:

   user.has_perm('app.view_model', obj) -> Option A

4. Quick Check:

   has_perm with object = correct syntax [OK]

Hint: Use has_perm with object argument for object-level checks [OK]

Common Mistakes:

• Omitting the object argument in has_perm
• Using non-existent methods like check_perm or can_access
• Confusing model-level and object-level permission checks

3. Given the code snippet:

from guardian.shortcuts import assign_perm
assign_perm('change_article', user, article)

if user.has_perm('change_article', article):
    print('Can edit')
else:
    print('Cannot edit')

What will be printed if the permission was assigned correctly?

medium

A. Cannot edit

B. Can edit

C. PermissionError

D. No output

Solution

1. Step 1: Understand permission assignment

   The assign_perm function assigns the 'change_article' permission to the user for the specific article object.

2. Step 2: Check permission with has_perm

   The user.has_perm('change_article', article) call returns True because the permission was assigned.

3. Final Answer:

   Can edit -> Option B

4. Quick Check:

   Assigned permission means has_perm returns True [OK]

Hint: Assign permission then has_perm returns True for that object [OK]

Common Mistakes:

• Assuming has_perm returns False without model-level permission
• Expecting exceptions instead of boolean
• Confusing permission names or forgetting object argument

4. Identify the error in this code snippet for checking object-level permission:

if user.has_perm('delete_post'):
    print('Can delete')
else:
    print('Cannot delete')

Assuming you want to check permission on a specific post object.

medium

A. Missing the object argument in has_perm method

B. Using wrong permission name 'delete_post'

C. Should use user.check_perm instead of has_perm

D. No error, code is correct

Solution

1. Step 1: Understand object-level permission check

   To check permission on a specific object, has_perm must include the object as the second argument.

2. Step 2: Analyze the code

   The code calls has_perm without the object, so it checks model-level permission only, not object-level.

3. Final Answer:

   Missing the object argument in has_perm method -> Option A

4. Quick Check:

   Object-level check needs object argument [OK]

Hint: Always pass object to has_perm for object-level checks [OK]

Common Mistakes:

• Forgetting the object argument in has_perm
• Using incorrect method names
• Assuming model-level permission covers object-level

5. You want to allow users to edit only the articles they own. Which approach correctly applies object-level permissions in Django?

hard

A. Use Django's default group permissions without object checks

B. Grant all users the 'change_article' permission globally on the Article model

C. Assign 'change_article' permission to each user only for their own article objects using django-guardian

D. Override the Article model's save method to check user ownership

Solution

1. Step 1: Understand the requirement

   Users should edit only their own articles, so permission must be specific to each article object.

2. Step 2: Evaluate options

   Assign 'change_article' permission to each user only for their own article objects using django-guardian assigns permission per object, matching the requirement. Grant all users the 'change_article' permission globally on the Article model grants global permission, allowing edits on all articles. Use Django's default group permissions without object checks ignores object-level control. Override the Article model's save method to check user ownership is unrelated to permissions.

3. Final Answer:

   Assign 'change_article' permission to each user only for their own article objects using django-guardian -> Option C

4. Quick Check:

   Object-level permission per user per object = Assign 'change_article' permission to each user only for their own article objects using django-guardian [OK]

Hint: Assign permissions per object to enforce ownership editing [OK]

Common Mistakes:

• Granting global permissions instead of per-object
• Ignoring object-level permission packages like django-guardian
• Trying to enforce ownership via model save method