Search field without gems

MISSION: field to search for post.title that contains characters #

posts_controller.rb

  def index
    if params[:title]
      @posts = Post.where('title ILIKE ?', "%#{params[:title]}%").order(created_at: :desc) #case-insensitive
    else
      @posts = Post.all.order(created_at: :desc)
    end
  end

any view (posts/index.html.haml or in a bootstrap navbar)

.form-inline.my-2.my-lg-0
  = form_tag(courses_path, method: :get) do
    .input-group
      = text_field_tag :title, params[:title], autocomplete: 'off', placeholder: "Find a course", class: 'form-control-sm'
      %span.input-group-append
        %button.btn.btn-primary.btn-sm{:type => "submit"}
          %span.fa.fa-search{"aria-hidden" => "true"}

.html.erb without bootstrap

<%= form_tag(posts_path, method: :get) do %>
  <%= text_field_tag :title, params[:title], autocomplete: 'off', placeholder: "post title" %>
  <%= submit_tag "Search" %>
<% end %>