Lazy loading vs eager loading in Flask - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set lazy loading for a relationship in SQLAlchemy.

Flask

posts = db.relationship('Post', lazy=[1])

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

A'joined'

B'immediate'

C'select'

D'dynamic'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'joined' loads eagerly, not lazily.

Using 'dynamic' returns a query, not a list.

Using lazy='select' means the related items are loaded only when accessed, which is lazy loading.

2fill in blank

medium

Complete the code to eagerly load related posts using joined loading.

Flask

user = User.query.options(db.[1]('posts')).first()

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

Ajoinedload

Blazyload

Cselectinload

Dnoload

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'lazyload' does lazy loading, not eager.

Using 'noload' disables loading the relationship.

joinedload tells SQLAlchemy to load the related posts in the same query using a SQL JOIN, which is eager loading.

3fill in blank

hard

Fix the error in the code to eagerly load posts using selectin loading.

Flask

user = User.query.options(db.[1]('posts')).first()

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

Ajoinedload

Bselectinload

Clazyload

Dnoload

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'lazyload' causes lazy loading, not eager.

Using 'noload' skips loading the relationship.

selectinload is another eager loading strategy that loads related items in a separate query but efficiently.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that includes only posts with more than 10 likes.

Flask

popular_posts = {post.id: post for post in user.posts if post.[1] > [2]

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

Alikes

B10

Ccomments

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'comments' instead of 'likes'.

Using 5 instead of 10 for the threshold.

This comprehension filters posts where the likes attribute is greater than 10.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps post titles to their authors' usernames for posts with more than 100 views.

Flask

post_authors = {post.[1]: post.author.[2] for post in posts if post.[3] > 100}

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

Atitle

Busername

Cviews

Dlikes

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'likes' instead of 'views' for filtering.

Using 'author' instead of 'username' for the value.

This comprehension creates a dictionary where keys are post titles and values are the usernames of the authors, filtering posts with more than 100 views.