rails collection_select params

Question

So I am trying to filter some data based on a collection_select drop down box.

I can successfully use a text_field_tag to filter the data, so I assume my filter is working fine, but I can't get the collection_select to do the same?

If I type a 1 into the text_field_tag, I generate "search"=>"1" as a part of the parameters, but if I select from the collection_select I get... {"utf8"=>"✓", "search"=>{"search"=>"1"},...

index.html.erb

 <h1>Students#index</h1>
<p>Find me in app/views/students/index.html.erb</p>

<%= form_tag students_path, :method => 'get' do %>
  <%= collection_select :search ,  :search.to_s, Tutor.all, :id, :name, prompt: true %>
  <%= submit_tag "search" %>
<% end %>

<% @students.each do |n| %>
  <li>
    <%= link_to n.first_name, student_path(n) %>
    <%= n.surname %> ..tutor is...
    <%= n.tutor.name %>
  </li>
 <% end %>

<%= params.inspect %>

<%= form_tag(students_path, :method=> "get", id: "search-form") do %>
  <%= text_field_tag :search, params[:search], placeholder: "Search Students" %>
  <%= submit_tag "Search", :name => nil %>
<% end %>

student.rb

class Student < ActiveRecord::Base
  belongs_to :tutor

  def self.search(search)
    where("tutor_id LIKE ?","%#{search }%")
  end
end

students_controller.rb

class StudentsController < ApplicationController
  def index
    if params[:search]
      @students = Student.search(params[:search])
    else
      @students = Student.all
    end
  end

Answer 1

That is how collection_select work. The first parameter of collection_select is an object not a method, so your params look like that.

Changing params[:search] to params[:search][:search] should solve your problem.

class StudentsController < ApplicationController
  def index
    if params[:search][:search]
      @students = Student.search(params[:search][:search])
    else
      @students = Student.all
    end
  end
end