Streamlining Rails Applications: Associating Devise Users with Posts

In the world of web development, one of the most powerful features of Rails is its seamless ability to manage user authentication through Devise. But what happens when you want to extend this functionality to allow users to create and manage their own resources, like posts? Let’s dive into how you can associate Devise users with posts in your Rails application to build richer, more interactive experiences.

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Step 1: Setting Up Your Models

To begin, we’ll create a Post model that includes a user_id field to link it to a specific user. This is achieved using Rails’ built-in references feature:

rails generate model Post title:string content:text user:references
rails db:migrate

This creates a user_id column in the posts table and establishes the groundwork for associating posts with users.

Next, define the relationships in the models:

User Model

class User < ApplicationRecord
  devise :database_authenticatable, :registerable, :recoverable, :rememberable, :validatable

  # Association with posts
  has_many :posts, dependent: :destroy
end

Post Model

class Post < ApplicationRecord
  belongs_to :user

  # Optional validations
  validates :title, :content, presence: true
end

Step 2: Configuring the Controller

Now, let’s set up a PostsController to manage post creation. Ensure that only authenticated users can create posts by using Devise’s authenticate_user! method.

Generate the Controller

rails generate controller Posts

Customize the Controller

Update the PostsController with the following logic:

class PostsController < ApplicationController
  before_action :authenticate_user!

  def new
    @post = Post.new
  end

  def create
    @post = current_user.posts.build(post_params) # Associate the post with the current user
    if @post.save
      redirect_to @post, notice: 'Post was successfully created.'
    else
      render :new
    end
  end

  def index
    @posts = Post.all
  end

  def show
    @post = Post.find(params[:id])
  end

  private

  def post_params
    params.require(:post).permit(:title, :content)
  end
end

The key line here is:

@post = current_user.posts.build(post_params)

This ensures that the post being created is automatically associated with the logged-in user.

Step 3: Updating Routes

In config/routes.rb, add routes for posts:

Rails.application.routes.draw do
  devise_for :users
  resources :posts
  root to: 'posts#index' # Set a default root route
end

Step 4: Building the Views

New Post Form

Create a form to allow users to submit posts in app/views/posts/new.html.erb:

<%= form_with model: @post, local: true do |form| %>
  <% if @post.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@post.errors.count, "error") %> prohibited this post from being saved:</h2>
      <ul>
        <% @post.errors.full_messages.each do |message| %>
          <li><%= message %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <div>
    <%= form.label :title %><br>
    <%= form.text_field :title %>
  </div>

  <div>
    <%= form.label :content %><br>
    <%= form.text_area :content %>
  </div>

  <div>
    <%= form.submit 'Create Post' %>
  </div>
<% end %>

Step 5: Testing the Association

To test this functionality:

1. Start the Rails server: rails server
2. Sign up a user at /users/sign_up.
3. Navigate to /posts/new to create a post.
4. Check that the post is saved with the user_id matching the logged-in user.

Step 6: Displaying User-Specific Posts

If you’d like to show posts created only by the logged-in user, update the index action:

def index
  @posts = current_user.posts
end

This restricts the displayed posts to those created by the authenticated user.

Conclusion

By associating Devise users with posts, you’ve unlocked a powerful feature for your Rails application. This foundation can be extended to more complex models and relationships, enabling users to interact with your app in meaningful ways. Whether you’re building a blog, a forum, or a social media platform, this pattern sets you on the path to success.

Happy coding! 🚀