Order and limit in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to order users by their creation date in ascending order.

Ruby on Rails

User.[1](:created_at)

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

Alimit

Border

Cwhere

Dselect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'limit' instead of 'order' to sort records.

Using 'where' which filters records but does not sort.

The order method sorts records by the given column.

2fill in blank

medium

Complete the code to limit the number of posts returned to 5.

Ruby on Rails

Post.[1](5)

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

Aorder

Bgroup

Climit

Dselect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'order' which sorts but does not limit.

Using 'group' which groups records but does not limit.

The limit method restricts the number of records returned.

3fill in blank

hard

Fix the error in the code to order products by price descending.

Ruby on Rails

Product.order(price: :[1])

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

Aasc

Bup

Cdown

Ddesc

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'asc' which orders ascending.

Using 'down' or 'up' which are not valid symbols.

Use :desc to order descending in Rails.

4fill in blank

hard

Fill both blanks to order comments by updated_at descending and limit to 10.

Ruby on Rails

Comment.[1](updated_at: :[2]).limit(10)

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

Aorder

Bdesc

Casc

Dlimit

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'asc' instead of 'desc' for descending order.

Using 'limit' instead of 'order' for sorting.

Use order with :desc to sort descending, then limit to restrict count.

5fill in blank

hard

Fill all three blanks to order articles by published_at ascending, limit to 3, and select only title and author.

Ruby on Rails

Article.[1](published_at: :[2]).[3](3).select(:title, :author)

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

Aorder

Basc

Climit

Dwhere

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'where' instead of 'limit' to restrict records.

Using 'desc' instead of 'asc' for ascending order.

Use order with :asc for ascending order, then limit to restrict results.

Practice

1. What does the order method do in Rails ActiveRecord queries?

easy

A. Sorts the records by a specified column

B. Limits the number of records returned

C. Filters records based on conditions

D. Joins two tables together

Solution

1. Step 1: Understand the purpose of order

   The order method sorts records by the column you specify, like sorting a list alphabetically.

2. Step 2: Differentiate from other methods

   limit controls how many records you get, where filters records, and joins combines tables. Only order sorts.

3. Final Answer:

   Sorts the records by a specified column -> Option A

4. Quick Check:

   Order = Sort [OK]

Hint: Order sorts data by column, limit controls count [OK]

Common Mistakes:

• Confusing order with limit
• Thinking order filters records
• Mixing order with joins

2. Which of the following is the correct syntax to get the first 5 users ordered by their creation date in Rails?

easy

A. User.limit(5).order(created_at)

B. User.order(:created_at).limit(5)

C. User.order_by(:created_at).limit(5)

D. User.limit(5).sort(:created_at)

Solution

1. Step 1: Check method names and order

   The correct ActiveRecord methods are order and limit. The method order_by and sort do not exist in this context.

2. Step 2: Confirm chaining order

   You can chain order then limit or vice versa, but the common and recommended way is order(:created_at).limit(5).

3. Final Answer:

   User.order(:created_at).limit(5) -> Option B

4. Quick Check:

   Correct syntax = User.order(:created_at).limit(5) [OK]

Hint: Use order then limit with correct method names [OK]

Common Mistakes:

• Using non-existent methods like order_by or sort
• Swapping method names incorrectly
• Incorrect chaining order causing errors

3. Given the code Product.order(price: :desc).limit(3).pluck(:price), what will be the output if prices are [10, 50, 30, 20, 40]?

medium

A. [10, 20, 30]

B. [40, 30, 20]

C. [50, 40, 30]

D. [30, 20, 10]

Solution

1. Step 1: Understand ordering by price descending

   The prices sorted descending are [50, 40, 30, 20, 10].

2. Step 2: Apply limit and pluck

   Limiting to 3 means we take the first three prices: [50, 40, 30].

3. Final Answer:

   [50, 40, 30] -> Option C

4. Quick Check:

   Order desc + limit 3 = [50, 40, 30] [OK]

Hint: Order desc sorts highest first, limit picks top records [OK]

Common Mistakes:

• Forgetting descending order
• Mixing ascending with descending
• Ignoring limit count

4. What is wrong with this Rails query? User.limit(5).order('name')

medium

A. limit cannot be used with order

B. The order argument should be a symbol, not a string

C. The order method must come before limit

D. The query is valid and will work correctly

Solution

1. Step 1: Check method chaining order

   In Rails, chaining limit before or after order works fine; order does not have to come first.

2. Step 2: Check argument type for order

   Passing a string like 'name' to order is valid syntax in Rails.

3. Final Answer:

   The query is valid and will work correctly -> Option D

4. Quick Check:

   limit + order chaining is flexible = The query is valid and will work correctly [OK]

Hint: Order and limit can be chained in any order [OK]

Common Mistakes:

• Thinking order must come before limit
• Believing order needs symbol not string
• Assuming limit and order cannot combine

5. You want to get the 3 most recent posts but only those with status 'published'. Which Rails query correctly combines filtering, ordering by newest first, and limiting?

hard

A. Post.where(status: 'published').order(created_at: :desc).limit(3)

B. Post.limit(3).order(created_at: :asc).where(status: 'published')

C. Post.order(:created_at).where(status: 'published').limit(3)

D. Post.where(status: 'published').limit(3).order(created_at: :asc)

Solution

1. Step 1: Filter posts by status 'published'

   Use where(status: 'published') to get only published posts.

2. Step 2: Order posts by newest first

   Use order(created_at: :desc) to sort posts from newest to oldest.

3. Step 3: Limit to 3 records

   Use limit(3) to get only the top 3 posts after filtering and ordering.

4. Final Answer:

   Post.where(status: 'published').order(created_at: :desc).limit(3) -> Option A

5. Quick Check:

   Filter + order desc + limit = Post.where(status: 'published').order(created_at: :desc).limit(3) [OK]

Hint: Filter first, then order desc, then limit [OK]

Common Mistakes:

• Limiting before filtering causing wrong results
• Ordering ascending instead of descending
• Mixing method order causing unexpected output