Form helpers (form_with) in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a form using form_with for a new @post object.

Ruby on Rails

<%= form_with model: [1] do |form| %>
  <%= form.text_field :title %>
  <%= form.submit %>
<% end %>

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

APost.new

Bpost

C@post

Dposts_path

Attempts:

3 left

💡 Hint

Common Mistakes

Using the class name instead of the instance variable.

Using the symbol or string instead of the model object.

The form_with helper uses the model object @post to build the form for that record.

2fill in blank

medium

Complete the code to create a form that submits to the posts_path URL with method POST.

Ruby on Rails

<%= form_with url: [1], method: :post do |form| %>
  <%= form.text_field :content %>
  <%= form.submit 'Create' %>
<% end %>

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

Aposts_path

Bnew_post_path

Cedit_post_path

Dpost_path

Attempts:

3 left

💡 Hint

Common Mistakes

Using singular path helpers which expect an ID.

Using the new or edit path helpers which are for GET requests.

The posts_path is the correct URL helper for creating a new post with POST method.

3fill in blank

hard

Fix the error in the form helper by completing the missing option to disable local submission (use AJAX).

Ruby on Rails

<%= form_with model: @comment, [1]: false do |form| %>
  <%= form.text_area :body %>
  <%= form.submit %>
<% end %>

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

Alocal

Bremote

Cajax

Dasync

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'remote' instead of 'local' option.

Using non-existent options like 'ajax' or 'async'.

The option local: false disables local submission and enables AJAX.

4fill in blank

hard

Fill both blanks to create a form with a text field for name and a submit button labeled 'Save'.

Ruby on Rails

<%= form_with model: @user do |form| %>
  <%= form.[1] :name %>
  <%= form.[2] 'Save' %>
<% end %>

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

Atext_field

Bsubmit

Ctext_area

Dbutton

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'text_area' instead of 'text_field' for single line input.

Using 'button' instead of 'submit' for the submit button.

Use text_field for the input and submit for the button with label.

5fill in blank

hard

Fill all three blanks to create a form that uses form_with with a model, disables local submission, and includes a password field.

Ruby on Rails

<%= form_with model: [1], [2]: false do |form| %>
  <%= form.[3] :password %>
  <%= form.submit 'Login' %>
<% end %>

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

A@user

Blocal

Cpassword_field

Dremote

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'remote' instead of 'local' for the option name.

Using 'text_field' instead of 'password_field' for password input.

Use the model instance @user, set local: false to enable AJAX, and use password_field for password input.

Practice

1. What is the main purpose of form_with in Rails?

easy

A. To create database tables automatically

B. To style buttons with CSS

C. To run JavaScript code on form submission

D. To create HTML forms that connect to models easily

Solution

1. Step 1: Understand what form_with does

   form_with is a helper in Rails that builds forms linked to models for easy data handling.

2. Step 2: Compare options

   Only To create HTML forms that connect to models easily describes creating forms connected to models. Others describe unrelated tasks.

3. Final Answer:

   To create HTML forms that connect to models easily -> Option D

4. Quick Check:

   form_with builds model forms = A [OK]

Hint: Remember: form_with builds forms linked to models [OK]

Common Mistakes:

• Thinking form_with styles buttons
• Confusing form_with with JavaScript functions
• Assuming form_with creates database tables

2. Which is the correct syntax to create a form for a @post model using form_with with local submission?

easy

A. form_with @post, remote: true do |form|

B. form_with model: @post, local: true do |form|

C. form_for @post, local: true do |form|

D. form_with model: @post, ajax: false do |form|

Solution

1. Step 1: Identify correct form_with syntax

   The correct syntax uses model: @post and local: true to disable AJAX.

2. Step 2: Check options for correctness

   form_with model: @post, local: true do |form| matches correct syntax. form_with @post, remote: true do |form| uses remote: true (AJAX enabled). form_for @post, local: true do |form| uses deprecated form_for. form_with model: @post, ajax: false do |form| uses invalid ajax option.

3. Final Answer:

   form_with model: @post, local: true do |form| -> Option B

4. Quick Check:

   Use model: and local: true for local form [OK]

Hint: Use model: and local: true for local forms [OK]

Common Mistakes:

• Using remote: true instead of local: true
• Using deprecated form_for helper
• Using invalid options like ajax: false

3. Given this code snippet:

form_with model: @user, local: true do |form|
  form.text_field :name
  form.submit 'Save'
end

What will happen when the user submits the form?

medium

A. The form submits data with a normal HTTP POST request

B. The form will not submit because of syntax error

C. The form sends data via AJAX without page reload

D. The form submits data but reloads the page with errors

Solution

1. Step 1: Analyze the local: true option

   Setting local: true disables AJAX, so the form submits with a normal HTTP request.

2. Step 2: Understand form submission behavior

   The form sends data via HTTP POST and reloads or redirects normally, no AJAX involved.

3. Final Answer:

   The form submits data with a normal HTTP POST request -> Option A

4. Quick Check:

   local: true means normal POST submission [OK]

Hint: local: true disables AJAX, so form submits normally [OK]

Common Mistakes:

• Assuming local: true enables AJAX
• Confusing syntax errors with correct code
• Thinking form reloads only on errors

4. Identify the error in this form_with usage:

form_with model: @article, local: true do |f|
  f.text_field :title
  f.submit
end

Why might this form not work as expected?

medium

A. The block variable f is invalid

B. Using local: true disables form submission

C. Missing = before form_with in ERB template

D. The form is missing a closing end keyword

Solution

1. Step 1: Check ERB syntax for form_with

   In ERB templates, form_with must be preceded by = to output the form HTML.

2. Step 2: Analyze other options

   Using local: true disables form submission is wrong because local: true enables normal submission. The block variable f is invalid is wrong; f is a valid block variable. The form is missing a closing end keyword is incorrect; the block is properly closed.

3. Final Answer:

   Missing = before form_with in ERB template -> Option C

4. Quick Check:

   Use <%= form_with ... %> to render form [OK]

Hint: Always use <%= form_with ... %> to render form in ERB [OK]

Common Mistakes:

• Omitting = in ERB for form_with
• Thinking local: true disables submission
• Confusing block variable names
• Forgetting to close the block

5. You want to create a form for a new @comment that submits without page reload using AJAX. Which is the correct way to write form_with?

hard

A. = form_with model: @comment do |form|

B. = form_with model: @comment, remote: true do |form|

C. = form_with @comment, local: false do |form|

D. = form_with model: @comment, local: true do |form|

Solution

1. Step 1: Understand AJAX behavior in form_with

   By default, form_with submits via AJAX unless local: true is set.

2. Step 2: Analyze options for AJAX submission

   = form_with model: @comment do |form| uses default AJAX submission. = form_with model: @comment, local: true do |form| disables AJAX with local: true. = form_with model: @comment, remote: true do |form| uses invalid remote: true (deprecated). = form_with @comment, local: false do |form| uses local: false which is not a valid option.

3. Final Answer:

   = form_with model: @comment do |form| -> Option A

4. Quick Check:

   Default form_with submits via AJAX unless local: true [OK]

Hint: Omit local: true for AJAX; default is AJAX submission [OK]

Common Mistakes:

• Using local: true disables AJAX
• Using deprecated remote: true option
• Setting invalid local: false option