forms

name	forms
description	Build Rails forms with Tailwind CSS, Turbo integration, and strong params validation
license	MIT

What I do

• Build forms using Rails form helpers (form_with, form_for)
• Style forms with Tailwind CSS and Flowbite components
• Handle form validation errors with Turbo/partial re-renders
• Configure strong params in controllers with params.expect

When to use me

• Creating new resource forms
• Modifying existing forms
• Adding form validation or error display
• Building nested forms

Project Conventions

Form Builder Pattern

<%= form_with model: [:organizer, @resource], class: "space-y-4" do |f| %>
  <% if @resource.errors.any? %>
    <div class="bg-red-100 border border-red-400 text-red-700 px-4 py-3 rounded">
      <ul>
        <% @resource.errors.full_messages.each do |message| %>
          <li><%= message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <div>
    <%= f.label :name, class: "block text-sm font-medium text-gray-700" %>
    <%= f.text_field :name, class: "mt-1 block w-full rounded-md border-gray-300 shadow-sm" %>
  </div>

  <div>
    <%= f.submit "Save", class: "bg-blue-700 text-white px-4 py-2 rounded-lg hover:bg-blue-800" %>
  </div>
<% end %>

Strong Params

• Rails 8: params.expect(model: [:field1, :field2])
• Array of permitted fields, not require+permit chain
• Example: params.expect(tournament: %i[name state start_time end_time])

Form Validation Flow

1. Controller: @resource.attributes = params → fails validation
2. Controller: render :edit, status: :unprocessable_entity
3. View: errors hash populated, form re-renders with error messages
4. Turbo: handles the 422 response, replaces the form partial

Field Types

• Text fields: f.text_field :name
• Text areas: f.text_area :description
• Date/time: f.datetime_field :start_time
• Selects: f.select :state, options_for_select(...)
• Checkboxes: f.check_box :accepted_terms
• File upload: f.file_field :cover (for ActiveStorage)
• Hidden: f.hidden_field :field

Turbo-Integrated Forms

• Forms in Turbo frames: form_with with data: { turbo_frame: "frame_id" }
• Turbo-preflighted submissions: automatic for Turbo-enabled forms
• Submit via Turbo method: data: { "turbo-method": :delete }
• Modal forms: wrapped in <turbo-frame id="modal"> with target: "_top"

Common Form Patterns

• Terms acceptance: f.check_box :accepted_terms + validation in model
• Cover photo upload: f.file_field :cover + has_one_attached :cover
• Nested attributes: For related records in a single form
• Organizer context: merge(event_organizer: current_organizer) in controller

Key Files

• app/views/registrations/new.html.erb — User registration form
• app/views/passwords/new.html.erb — Password reset form
• app/controllers/organizer/tournaments_controller.rb — Strong params with params.expect