Form_with helper in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

Ruby on Rails

<%= form_with model: [1] do |form| %>
  <!-- form fields here -->
<% end %>

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

Apost

B@post

CPost.new

Dposts

Attempts:

3 left

💡 Hint

Common Mistakes

Using the class name instead of the instance variable.

Using a symbol or string instead of the object.

The form_with helper uses the model: option with an instance variable like @post to build the form for that object.

2fill in blank

medium

Complete the code to create a text field for the :title attribute inside the form builder.

Ruby on Rails

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

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

Ainput

Btext_area

Clabel

Dtext_field

Attempts:

3 left

💡 Hint

Common Mistakes

Using input which is not a form builder method.

Using text_area which creates a multi-line box.

Using label which only creates a label.

The text_field method creates a single-line text input for the specified attribute.

3fill in blank

hard

Fix the error in the form_with call to submit the form with a custom URL '/posts/create'.

Ruby on Rails

<%= form_with url: [1] do |form| %>
  <%= form.submit 'Save' %>
<% end %>

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

A:posts_create

Bposts_create_path

C'/posts/create'

D/posts/create

Attempts:

3 left

💡 Hint

Common Mistakes

Using a symbol instead of a string.

Using a path helper without calling it.

Not quoting the string path.

The URL must be a string wrapped in quotes to be valid Ruby syntax.

4fill in blank

hard

Fill both blanks to create a form that submits with method PATCH to update @article.

Ruby on Rails

<%= form_with model: [1], method: [2] do |form| %>
  <%= form.submit %>
<% end %>

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

A@article

Bpatch

C:patch

Dupdate

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string instead of a symbol for method.

Using the class name instead of the instance variable.

The model: option uses the instance variable @article. The method: option requires a symbol :patch to specify the HTTP method.

5fill in blank

hard

Fill all three blanks to create a form with a text field for :name, a label, and a submit button with text 'Send'.

Ruby on Rails

<%= form_with model: @user do |form| %>
  <%= form.[1] :name %>
  <%= form.[2] :name %>
  <%= form.[3] 'Send' %>
<% end %>

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

Atext_field

Blabel

Csubmit

Dbutton

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up label and text_field methods.

Using button instead of submit for the submit button.

Omitting the label.

The text_field creates the input box, label creates the label for the input, and submit creates the submit button with the given text.

Practice

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

easy

A. To create HTML forms linked to models with automatic URL and method handling

B. To style forms using CSS classes automatically

C. To validate form inputs on the client side

D. To generate JavaScript code for form animations

Solution

1. Step 1: Understand the role of form_with

   The form_with helper builds forms in Rails and connects them to models.

2. Step 2: Identify what it automates

   It automatically sets the form's URL and HTTP method based on the model's state.

3. Final Answer:

   To create HTML forms linked to models with automatic URL and method handling -> Option A

4. Quick Check:

   form_with purpose = create linked forms [OK]

Hint: Remember: form_with links forms to models automatically [OK]

Common Mistakes:

• Thinking form_with styles forms
• Confusing form_with with client-side validation
• Assuming form_with generates JavaScript animations

2. Which of the following is the correct syntax to create a form using form_with for a model instance @post with normal (non-AJAX) submission?

easy

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

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

C. form_with model: @post, remote: true do |form|

D. form_with url: posts_path, method: :get do |form|

Solution

1. Step 1: Identify how to disable AJAX

   Using local: true disables AJAX and makes the form submit normally.

2. Step 2: Check the correct syntax for model binding

   The correct syntax is form_with model: @post, local: true do |form|.

3. Final Answer:

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

4. Quick Check:

   local: true disables AJAX [OK]

Hint: Use local: true for normal form submission [OK]

Common Mistakes:

• Omitting local: true for non-AJAX forms
• Using remote: true which enables AJAX
• Using method :get for form submission instead of post

3. Given the following code snippet, what will be the HTTP method used when submitting the form?

form_with model: @article do |form|
  # form fields here
end

medium

A. DELETE if @article is persisted, POST if new

B. GET always

C. POST if @article is a new record, PATCH if it is persisted

D. PUT always

Solution

1. Step 1: Understand form_with method behavior

   When linked to a model, form_with uses POST for new records and PATCH for existing records.

2. Step 2: Apply to @article

   If @article is new, method is POST; if persisted, method is PATCH.

3. Final Answer:

   POST if @article is a new record, PATCH if it is persisted -> Option C

4. Quick Check:

   form_with method depends on record state [OK]

Hint: New record = POST, existing record = PATCH [OK]

Common Mistakes:

• Assuming GET is used for form submission
• Confusing PUT with PATCH
• Thinking DELETE is used automatically

4. Identify the error in this form_with usage:

form_with model: @user, local: true do
  text_field :name
end

medium

A. Missing block variable for form builder

B. local: true is invalid option

C. text_field should be text_field_tag

D. model: @user should be url: user_path(@user)

Solution

1. Step 1: Check block syntax

   The block must accept a form builder variable, e.g., do |form|.

2. Step 2: Check usage of form builder methods

   Inside the block, form builder methods like form.text_field :name must be called.

3. Final Answer:

   Missing block variable for form builder -> Option A

4. Quick Check:

   Block needs form variable for fields [OK]

Hint: Always use |form| block variable with form_with [OK]

Common Mistakes:

• Omitting the block variable
• Calling form builder methods without prefix
• Confusing text_field with text_field_tag

5. You want to create a form for a new @comment that submits normally (no AJAX), includes a text area for content, and a submit button labeled 'Post Comment'. Which of the following is the correct complete form_with usage?

hard

A. form_with @comment do |form|
form.text_field :content
form.submit
end

B. form_with model: @comment, remote: true do |form|
form.text_area :content
form.submit 'Post Comment'
end

C. form_with url: comments_path, method: :post do |form|
form.text_area :content
form.submit 'Post Comment'
end

D. form_with model: @comment, local: true do |form|
form.text_area :content
form.submit 'Post Comment'
end

Solution

1. Step 1: Ensure normal submission

   Use local: true to disable AJAX and submit normally.

2. Step 2: Use correct form builder methods

   Use form.text_area :content for the text area and form.submit 'Post Comment' for the button label.

3. Final Answer:

   form_with model: @comment, local: true do |form| form.text_area :content form.submit 'Post Comment' end -> Option D

4. Quick Check:

   local: true + text_area + submit label [OK]

Hint: Use local: true and form builder methods for fields [OK]

Common Mistakes:

• Using remote: true which enables AJAX
• Using text_field instead of text_area for content
• Omitting the submit button label