View helpers in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What does this Rails view helper output?

Given the helper method below, what will be the rendered HTML output when called in a view?

module ApplicationHelper
  def greeting(name)
    content_tag(:p, "Hello, #{name}!")
  end
end

# Called in view as: <%= greeting('Alice') %>

Ruby on Rails

module ApplicationHelper
  def greeting(name)
    content_tag(:p, "Hello, #{name}!")
  end
end

A <p>greeting('Alice')</p>

B Hello, Alice!

C <div>Hello, Alice!</div>

D <p>Hello, Alice!</p>

💡 Hint

Remember that content_tag creates an HTML tag with content inside.

The content_tag helper wraps the string inside the specified HTML tag, here a paragraph

. So the output is a paragraph with the greeting text.

📝 Syntax

intermediate

Which option correctly defines a Rails helper method to format a date?

You want to create a helper method that formats a Date object as 'Month day, Year' (e.g., 'April 5, 2024'). Which of the following method definitions is correct?

A

def format_date(date)
  date.strftime('%B %d, %Y')
end

B

def format_date(date)
  date.to_s('%B %d, %Y')
end

C

def format_date(date)
  date.format('%B %d, %Y')
end

D

def format_date(date)
  date.strftime('%b %d %Y')
end

💡 Hint

Check the Ruby Date class methods for formatting dates.

The strftime method formats dates with the given pattern. '%B' is full month name, '%d' is day with leading zero, '%Y' is four-digit year.

🔧 Debug

advanced

Why does this helper method cause an error?

Consider this helper method:

def link_to_profile(user)
  link_to "Profile", user_path(user.id)
end

When called with link_to_profile(nil), it raises an error. Why?

Ruby on Rails

def link_to_profile(user)
  link_to "Profile", user_path(user.id)
end

A Because user_path cannot accept an integer argument

B Because user is nil, calling user.id raises NoMethodError

C Because link_to requires a block when user is nil

D Because the method link_to_profile is missing a return statement

💡 Hint

What happens if you call a method on nil in Ruby?

Calling user.id when user is nil causes NoMethodError since nil has no id method.

❓ state_output

advanced

What is the output of this helper with conditional logic?

Given this helper method:

def status_badge(active)
  if active
    content_tag(:span, "Active", class: "badge badge-success")
  else
    content_tag(:span, "Inactive", class: "badge badge-danger")
  end
end

# Called in view as: <%= status_badge(false) %>

Ruby on Rails

def status_badge(active)
  if active
    content_tag(:span, "Active", class: "badge badge-success")
  else
    content_tag(:span, "Inactive", class: "badge badge-danger")
  end
end

A <span class="badge badge-danger">Inactive</span>

B <span class="badge badge-success">Active</span>

C <span>Inactive</span>

D Active

💡 Hint

Check the condition and which content_tag is returned.

When active is false, the else branch runs, producing a span with class 'badge badge-danger' and text 'Inactive'.

🧠 Conceptual

expert

Which statement about Rails view helpers is true?

Choose the correct statement about Rails view helpers:

A Helpers can only be used in views and never in controllers or models

B Helpers are automatically available in views but must be explicitly included in controllers

C Helpers can be used to keep view templates clean by moving complex logic out of them

D Helpers must always return raw HTML strings without escaping

💡 Hint

Think about the purpose of helpers in MVC architecture.

Helpers are designed to keep views simple by moving formatting and presentation logic out of templates.