Why views present data in Ruby on Rails - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to display the user's name in the view.

Ruby on Rails

<h1>Welcome, [1]!</h1>

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

A{{ user.name }}

[e-mail]

C<%= @user.name %>

Duser.name

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to use <%= %> to output data

Using JavaScript or other syntax instead of Ruby in views

In Rails views, you use <%= %> to embed Ruby code that outputs data. Here, @user.name is displayed with <%= %>.

2fill in blank

medium

Complete the code to loop through all posts and show their titles in the view.

Ruby on Rails

<ul>
  <% @posts.each do |[1]| %>
    <li><%= [1].title %></li>
  <% end %>
</ul>

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

Apost

Bposts

Citem

Dp

Attempts:

3 left

💡 Hint

Common Mistakes

Using plural variable names inside the block

Not matching the block variable with the collection items

The block variable inside each do |...| should be singular to represent each item. Here, post is correct.

3fill in blank

hard

Fix the error in the code to correctly display the user's email.

Ruby on Rails

<p>Email: [1]</p>

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

[e-mail]

B<%= user.email %>

Cuser.email

D<%= @user.email %>

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting <%= %> so the code doesn't output anything

Using local variables instead of instance variables

To display data in a Rails view, use <%= %> with the instance variable @user.email.

4fill in blank

hard

Fill both blanks to create a link to the user's profile with the user's name as link text.

Ruby on Rails

<%= link_to [1], [2] %>

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

[e-mail]

Buser_path(@user)

Cprofile_path

D:user

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the order of arguments

Using symbols instead of path helpers

link_to takes the link text first, then the path. Here, @user.name is the text, and user_path(@user) is the URL.

5fill in blank

hard

Fill all three blanks to display a list of product names with prices formatted as currency.

Ruby on Rails

<ul>
  <% @products.each do |[1]| %>
    <li><%= [2] %> - <%= number_to_currency([3]) %></li>
  <% end %>
</ul>

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

Aproduct

Bproduct.name

Cproduct.price

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names

Not formatting price as currency

The block variable is product. Use product.name for the name and product.price for the price formatted with number_to_currency.

Practice

1. Why do views in Rails present data to users?

easy

A. To store data in the database

B. To turn raw data into readable web pages

C. To handle user login and authentication

D. To manage server configuration settings

Solution

1. Step 1: Understand the role of views in MVC

   Views are responsible for showing data to users in a readable format, usually as HTML pages.

2. Step 2: Differentiate views from other parts

   Controllers prepare data, models handle data storage, but views present data clearly to users.

3. Final Answer:

   To turn raw data into readable web pages -> Option B

4. Quick Check:

   Views present data = To turn raw data into readable web pages [OK]

Hint: Views display data as pages, not store or process it [OK]

Common Mistakes:

• Confusing views with controllers or models
• Thinking views handle data storage
• Assuming views manage server settings

2. Which of the following is the correct way to insert Ruby data into a Rails view using ERB syntax?

easy

A. <% @user.name %>

B. [[ @user.name ]]

C. {{ @user.name }}

D. <%= @user.name %>

Solution

1. Step 1: Identify ERB syntax for output

   In Rails views, <%= %> outputs Ruby code result into HTML.

2. Step 2: Compare options

   <% %> runs Ruby code but does not output it; {{ }} and [[ ]] are not Rails ERB syntax.

3. Final Answer:

   <%= @user.name %> -> Option D

4. Quick Check:

   ERB output tag = <%= @user.name %> [OK]

Hint: Use <%= %> to show Ruby data in views [OK]

Common Mistakes:

• Using <% %> which does not output data
• Confusing with other template syntaxes like {{ }}
• Forgetting to use equals sign for output

3. Given the controller sets @items = ['apple', 'banana', 'cherry'], what will this view code output?

<ul>
  <% @items.each do |item| %>
    <li><%= item.upcase %></li>
  <% end %>
</ul>

medium

A. APPLEBANANACHERRY

B. applebananacherry

C. ItemItemItem

D. Syntax error due to missing output tag

Solution

1. Step 1: Understand the loop and method

   The code loops over @items and outputs each item in uppercase inside <li> tags.

2. Step 2: Check output tags and method

   <%= item.upcase %> outputs the uppercase string; the loop is correct.

3. Final Answer:

   <ul><li>APPLE</li><li>BANANA</li><li>CHERRY</li></ul> -> Option A

4. Quick Check:

   Loop with upcase output =
   • APPLE
   • BANANA
   • CHERRY
   [OK]

Hint: Look for <%= %> to output transformed data inside loop [OK]

Common Mistakes:

• Confusing <% %> with <%= %> causing no output
• Ignoring the upcase method effect
• Assuming original lowercase output

4. Identify the error in this Rails view snippet:

<ul>
  <% @products.each do |product| %>
    <li><%= product.name %></li>
  <% end %>
</ul>

medium

A. No error, code is correct

B. Using <%= inside <% block without closing properly

C. Incorrect ERB output tag syntax

D. Missing closing tag for <li>

Solution

1. Step 1: Inspect ERB tags inside the loop

   The code uses proper ERB syntax: <% %> for the loop, <%= product.name %> for output, and HTML tags correctly placed.

2. Step 2: Verify no syntax issues

   All tags are properly opened and closed; no mixing of ERB and HTML incorrectly.

3. Final Answer:

   No error, code is correct -> Option A

4. Quick Check:

   Valid Rails ERB view code = No error, code is correct [OK]

Hint: Ensure ERB tags <%= %> wrap only Ruby code, not HTML [OK]

Common Mistakes:

• Placing HTML closing bracket inside ERB tag
• Confusing <% and <%= tags
• Assuming no syntax error when mixing tags

5. You want to display a list of users with their email only if the email is present. Which view code correctly presents this conditional data?

<ul>
  <% @users.each do |user| %>
    <li>
      <%= user.name %>
      <% if user.email.present? %>
        (<%= user.email %>)
      <% end %>
    </li>
  <% end %>
</ul>

hard

A. Syntax error due to missing output tags

B. Always shows email even if empty

C. Correctly shows name and email only if email exists

D. Does not loop through users properly

Solution

1. Step 1: Analyze the loop and conditional

   The code loops over @users and shows user.name always.

2. Step 2: Check conditional email display

   The if condition checks if email is present, then outputs it inside parentheses.

3. Step 3: Verify ERB syntax correctness

   Output tags <%= %> are used properly for name and email; control flow tags <% %> for condition.

4. Final Answer:

   Correctly shows name and email only if email exists -> Option C

5. Quick Check:

   Conditional display with correct ERB = Correctly shows name and email only if email exists [OK]

Hint: Use <% if %> for conditions, <%= %> to output data [OK]

Common Mistakes:

• Using <%= for if without closing properly
• Outputting email without checking presence
• Forgetting to close loop or condition tags