Form-based Workflow

This guide covers setting up the new action, building the form with form_for, handling validation errors, and connecting it all to your model.

Introduction

While we've created articles from the console, users need a web interface to add content. This document covers creating HTML forms and backend processing to submit articles.

Creating the NEW Action

Route Configuration

The RESTful route resources :articles sets up /articles/new for creating articles.

Controller Setup

Add to app/controllers/articles_controller.rb:

def new
  @article = Article.new
end

View Template

Create app/views/articles/new.html.erb:

<h1>Create a New Article</h1>

Building the Form

Form Implementation

Add to new.html.erb:

<%= form_for(@article) do |f| %>
  <ul>
  <% @article.errors.full_messages.each do |error| %>
    <li><%= error %></li>
  <% end %>
  </ul>
  <p>
    <%= f.label :title %><br />
    <%= f.text_field :title %>
  </p>
  <p>
    <%= f.label :body %><br />
    <%= f.text_area :body %>
  </p>
  <p>
    <%= f.submit %>
  </p>
<% end %>

Form Components

form_for: Creates form for @article
f.label: Creates HTML label
f.text_field: Single-line text input
f.text_area: Multi-line text input
f.submit: Submit button

Processing Form Data

Create Action

Add to controller:

def create
  @article = Article.new(article_params)
  @article.save
  redirect_to article_path(@article)
end

Strong Parameters

Add private method for security:

private

def article_params
  params.require(:article).permit(:title, :body)
end

Deleting Articles

Delete Link

Add to show.html.erb:

<%= link_to "delete", article_path(@article), method: :delete, data: { confirm: "Really delete the article?" } %>

Destroy Action

Add to controller:

def destroy
  @article = Article.find(params[:id])
  @article.destroy
  redirect_to articles_path
end

Editing Articles

Edit Workflow

Similar to new/create pattern:

edit displays form
update processes changes

Edit Link

Add to show.html.erb:

<%= link_to "edit", edit_article_path(@article) %>

Edit Action

Add to controller:

def edit
  @article = Article.find(params[:id])
end

Edit Template

Create app/views/articles/edit.html.erb:

<h1>Edit an Article</h1>
<%= render partial: 'form' %>

Form Partial

Create app/views/articles/_form.html.erb with shared form code.

Update Action

Add to controller:

def update
  @article = Article.find(params[:id])
  @article.update(article_params)
  redirect_to article_path(@article)
end

Flash Messages

Adding Messages

Example for update action:

flash.notice = "Article '#{@article.title}' Updated!"

Displaying Messages

Add to app/views/layouts/application.html.erb:

<p class="flash"><%= flash.notice %></p>

Setting Root Route

In config/routes.rb:

root to: 'articles#index'

Git Workflow

Committing Changes

git add -A
git commit -m "form-based workflow feature completed"
git push

Resetting Changes

To roll back to first commit:

git log
git reset --hard [commit-hash]

Key Concepts

Form Helpers: Rails provides helpers like form_for to generate HTML forms
Strong Parameters: Security measure to whitelist form parameters
RESTful Routes: Standardized URL patterns for CRUD operations
DRY Views: Using partials to avoid code duplication
User Feedback: Flash messages for status updates

Form-based Workflow

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