I am trying to add a search functionality to my ruby on rails application. The search works fine but how can I add a validation so it displays when the search is empty?

I have tried adding `required: true` but that doesn't seem to do much. 

index.html.erb:

```
<%= form_tag topics_path, :method => 'get' do %>
  <%= text_field_tag :search, params[:search], required: true %>
  <%= submit_tag "Search" %>   
<% end %

```

topics\_controller:

```
def index
@topics = Topic.search(params[:search]).paginate(:page => params[:page], :per_page => 5)
end

```

topics.rb

```
def self.search(search)
        if search 
            where(["title LIKE ?","%#{search}%"])
        else
        all 
    end

```

I expect the output to be:
1. Search for particular topic
2. There is no topics within that field so a validation is displayed such as "no results found, please try again"