Simple search

article.rb [ MODELO ]

class Article < ActiveRecord::Base

  belongs_to :user
  
  def self.search(search)
    where("title LIKE ?", "%#{search}%")
  end

end

article_controller.rb

  def index
    @articles = Articles.all

    if params[:search]
      @articles = Article.search(params[:search]).order("created_at DESC")
    else
      @articles = Article.all.order("created_at DESC")
    end

  end

index.html.erb

<%= form_tag(articles_path, :method => "get", id: "search-form") do %>
  <%= text_field_tag :search, params[:search], placeholder: "Buscar articulos", class: 'search' %>
  <%= submit_tag "Buscar", :title => nil, class: 'btn' %>
<% end %>