Handling Form Submissions and Error Handling in Ruby on Rails

One of the key features of any web application is the ability to handle form submissions and provide error handling for any potential issues that may arise. In Ruby on Rails, this process is made easy with the built-in functionality provided by the framework. In this article, we will explore how to handle form submissions and effectively manage errors in a Ruby on Rails application.

Form Submissions

Ruby on Rails provides a straightforward way of handling form submissions through the use of controllers and views. Let's take a look at the following example to understand how this works:

# app/controllers/articles_controller.rb

class ArticlesController < ApplicationController
  def new
    @article = Article.new
  end

  def create
    @article = Article.new(article_params)

    if @article.save
      redirect_to @article
    else
      render 'new'
    end
  end

  private

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

In the above example, we have a new action that initializes a new instance of the Article model. The corresponding view (new.html.erb) then renders a form for creating a new article.

When the form is submitted, the create action is triggered. First, we create a new Article object with the parameters provided by the user. If the article is successfully saved to the database, we redirect the user to the newly created article's page. Otherwise, we re-render the new view, allowing the user to correct any errors.

Error Handling

Error handling is an essential part of any form submission process. In Ruby on Rails, error handling can be easily achieved with the help of the Rails validation framework and the use of flash messages.

Let's enhance the previous example by adding some validations to the Article model:

# app/models/article.rb

class Article < ApplicationRecord
  validates :title, presence: true
  validates :content, presence: true
end

With these validations in place, any submitted form that does not fulfill the validation criteria will result in an error.

Next, we can modify the new view to display these errors:

<!-- app/views/articles/new.html.erb -->

<% if @article.errors.any? %>
  <div id="error_explanation">
    <h2><%= pluralize(@article.errors.count, "error") %> prohibited this article from being saved:</h2>
    <ul>
      <% @article.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
    </ul>
  </div>
<% end %>

<%= form_with model: @article, url: articles_path do |form| %>
  <!-- form fields and submit button -->
<% end %>

In the above code snippet, we check if there are any errors associated with the @article object. If there are, we display an error message with a list of the specific validation errors.

Finally, when an error occurs, we can provide the user with helpful flash messages in the controller:

# app/controllers/articles_controller.rb

# ...

def create
  @article = Article.new(article_params)

  if @article.save
    redirect_to @article, notice: 'Article was successfully created.'
  else
    flash.now[:alert] = 'There was an error while creating the article.'
    render 'new'
  end
end

# ...

In the example above, we use the notice key to display a success flash message after a successful creation. On the other hand, we use the alert key to display an error message when there is an issue with creating the article.

By leveraging Rails' built-in features, we have seen how easy it is to handle form submissions and error handling in a Ruby on Rails application. This allows us to create robust and user-friendly web applications while ensuring data integrity and providing clear feedback to the users.