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Rails: display unique records in each cycle

I have a product display page that displays all of the products on a website. Here I want to filter products according to their owner. First, I show the usernames on the page using each loop:

<% @products.each do |p| %>
   <%= link_to p.user.profile.first_name, store_index_path %>
<% end %>

But since the owner has multiple products, his name appears multiple times. How do I show the name only once?

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3 answers


In a simple way, you can do the following:



<% @products.map(&:user).uniq.each do |u| %>
  <%= link_to u.profile.first_name, store_index_path %>
<% end %>
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You can use group_by to create a User => [Products] hash. You then iterate through a unique set of users, display information about that owner, and then show each product to that user.



<% products_by_owner = @product.group_by(&:user) %>
<% products_by_owner.keys.each do |user| %>
  <%= link_to p.user.profile.first_name, store_index_path %>
  <% products_by_owner[user].each do |product| %>
    <%= link_to product.name, store_index_path %>
  <% end %>
<% end %>
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You can use group_by

to create a hash with users as keys and product arrays as values:

# Eager loading of users will prevent multiple database hits.
# Using find:
@products = Product.find(:all, :include => :user).group_by(&:user)

# using relations:
@products = Product.where(:some_condition => 'etc').includes(:user).group_by(&:user)

In view:

<% @products.each do |user, user_products| %>
  <%= link_to p.user.profile.first_name, store_index_path %>
  <% user_products.each do |product| %>
     ...
  <% end %>
<% end %>
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