Extra Details

Let's make a small addition and improvement to the store.

user like count

Below the like button, can you display the number of users who liked the product?

Guideline: You already declared that each product has_many likes, so can you use this relationship to display a number?

<p><%= @product.likes.size %> users like this.</p>

errors and bugs

What happens when someone who isn't logged in visits /my_page? Try it out:

Rails provides a helpful error page so you can see what went wrong.

undefined method `liked_products' for nil:NilClass

"undefined method" means your code called a method on something that didn't have that method defined anywhere. In this case, it tried calling liked_products on nil, but nil doesn't have such a method. Rails shows you where the code was called, so you can identify the issue quickly:

 <%= render current_user.liked_products %>

current_user was a devise method to return the signed-in user, and you could then call any of User's methods, such as liked_products. However, if the visitor isn't signed-in, current_user will return nil and cause the above problem.

To fix this error, we'll want to prevent visitors who aren't signed in from visiting this page. Is there a Devise method that can help us with this?

Fortunately, Devise provides the method :authenticate_user! and shows how to use it.

Add the following code to your UsersController:

before_action :authenticate_user!

Now try visiting the page again. This time, you'll be prompted to sign in. After signing in, you'll be redirected to /my_page.