Why caching improves response times in Ruby on Rails - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to cache the result of a method call in Rails.

Ruby on Rails

Rails.cache.[1]('user_1') { User.find(1) }

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

Afetch

Bstore

Cread

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'read' only reads without storing new data.

Using 'store' requires a value, not a block.

The fetch method tries to read from cache and runs the block if the cache is empty, storing the result.

2fill in blank

medium

Complete the code to expire a cached fragment in Rails.

Ruby on Rails

expire_fragment([1])

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Acache_key_for_users

BUser.all

C:all_users

D'all_users'

Attempts:

3 left

💡 Hint

Common Mistakes

Passing an ActiveRecord relation instead of a cache key string.

Using a symbol instead of a string key.

The expire_fragment method takes the cache key string to remove the cached fragment.

3fill in blank

hard

Fix the error in the caching code to properly cache a view fragment.

Ruby on Rails

<% cache [1] do %>
  <p>Cached content here</p>
<% end %>

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AUser.all

B'user_list'

C:user_list

Duser_list

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a variable without quotes causing undefined variable error.

Using a symbol instead of a string key.

The cache helper expects a string or cache key to identify the fragment. Quotes are needed for a string key.

4fill in blank

hard

Fill both blanks to create a cache key with a timestamp to expire cache after update.

Ruby on Rails

cache_key = "users/[1]-#{User.maximum(:[2])}"

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Alist

Bupdated_at

Ccreated_at

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'created_at' which doesn't change on updates.

Using 'count' which doesn't reflect update time.

The cache key includes 'list' and the 'updated_at' timestamp to expire cache when users update.

5fill in blank

hard

Fill all three blanks to write a method that caches a user's profile with expiration.

Ruby on Rails

def cached_profile(user)
  Rails.cache.[1]("profile_#{user.[2]", expires_in: [3]) do
    user.profile_data
  end
end

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Afetch

Bid

C5.minutes

Dstore

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'store' which requires a value, not a block.

Using 'name' instead of 'id' for cache key.

Not setting expiration time.

The method uses fetch to get or store the cache, uses the user's id in the key, and sets expiration to 5 minutes.