rails 3.2 searching action. how to pass results to another action

I should create a search page in which i have to save in an Array all the results of the searching. I had two problems:

1) I used the following statement:

Company.joins(:references).where(sql_string)

that returns an ActiveRecord:Relation and it's not good for me cause i have to display these results in the index action , in which i use an each statement. So , to overcame this problem i used the to_a. I checked the .class of my variable and with the to_a it passed from ActiveRecord:Relation to Array. So , it seems that this solve the problem.

Company.joins(:references).where(sql_string).to_a

2) Now, i have to pass this variable (Array) into my index action. I executed the search in the action called search:

def search
   ...
   @companies = Company.joins(:references).where(sql_string).to_a
end

Now, i want to pass this to index:

def index
  @companies ||= Company.all
end

I used @companies ||= Company.all cause i think that the @companies is and istance variable and it should be available in all the actions of the class. Isn't it? By the way, it doesn't workl. I mean , the results are not shared through the two methods. Also , in the search action i don't know how to call index action. I used the redirect_to but this bring me to another problem.

def search
   ...
   @companies = Company.joins(:references).where(sql_string).to_a
   redirect_to companies_index_path
end

The second time i call the search action it brings me into the index action.As i insered the searching value. At really he still had the past searching in memory, and i don't want this behavior. So , in other words, i want to:

1. passing @companies searching result to index action.

2. avoid the loop between search-index. So in every new request resets the old searching.

3. i want to know if it's correct the casting with the to_a to bring an ActiveRecord:Relation to Array.

Thank You.