Question

I have implemented a simple search functionality for my rails 3 blog application. I want to validate it, in such a way, that with non-matching keywords, or when the search text field is blank, & when user clicks search button, it should display a message saying “your search criteria is invalid. Please try using valid keywords”

My Code is as follows :

In Post Model,

class Post < ActiveRecord::Base
attr_accessible :title, :body
validates_presence_of :search
validates :title, :presence => true, :uniqueness => true
validates :body, :presence => true, :uniqueness => true
  def self.search(search)
    if search
      where("title LIKE ? OR body LIKE ?","%#{search.strip}%","%#{search.strip}%")
    else
      scoped
    end
  end
end

In Post Controller,

 class PostsController < ApplicationController
  def index    
   @posts=Post.includes(:comments).search(params[:search])
   .paginate(per_page:2,page:params[:page]).order("created_at DESC")
  end
end

In Posts/index.html.erb (Views)

<div class = "search">
 <span>
  <%= form_tag(posts_path, :method => :get, :validate => true) do %>
    <p>
    <%= text_field_tag (:search), params[:search] %>
    <%= submit_tag 'Search' %>
  </br>
    <% if params[:search].blank? %>
    <%= flash[:error] = "Sorry... Your Search criteria didnt match. 
     Please try using  different keyword." %>
    <% else %>
    </p>
  <% end %>  
  </p>
  <% end %>
 </span>
</div>

Answer 1

Use ActiveModel for a tableless model with validations – maybe a model like PostSearch, on which you could add validations like you would for any other model.

the model:

class PostSearch
  include ActiveModel::Validations
  include ActiveModel::Conversion
  extend ActiveModel::Naming

  attr_accessor :input

  validates_presence_of :input
  validates_length_of :input, :maximum => 500

end

and your form:

<%= form_for PostSearch.new(), :url=>posts_path, :method=>:get, :validate=>true do |f| %>
  <p>
    <%= f.label :input %><br />
    <%= f.text_field :input %>
  </p>
  <p><%= f.submit "Search" %></p>
<% end %>

Pair it with client side validations gem a good user experience.

Info on ActiveModel:

http://railscasts.com/episodes/219-active-model

Railscast source code:

https://github.com/ryanb/railscasts-episodes/tree/master/episode-219/