Class variable uninitialized error in ruby on rails

Question

Here's the code:

class MulticastController < ApplicationController
    @@groups=Array.new
    @@groups=[]

    @@group_name=Array.new
    @@group_name=[]

    def getResults
        @@groups
        @@group_name
        if request.post?

             if params[:creategroup] #makes a new group
                  @@groups << searchHash
                  @@group_name << params[:groupname]

                  if @@groups.size>5
                      @@groups[0].delete
                      @@group_name[0].delete
                  end

             end

            if params[:displaygroup] 
                @@group_name.each_with_index do |gr,i|
                if(gr==params[:inputgroupname])
                    @results=Person.where(@@groups[i]).to_a
                    render :new_results, :layout => false
                end
            end
    end

On the views portion I have-

        <div class="span6 service">
            <legend>Groups</legend>
            <% group_name.each do|grp|%>
                <%= grp %><br>
            <%end %><br><br>
            <input type="hidden" name="displaygroup" value="1">
            <div>
                <input type="text" name="inputgroupname" value="inputgroupname">
            </div>

I dont know what to do, its giving me an " uninitialized class variable @@group_name in ActionView::CompiledTemplates " error.

I want the variables group and group_name to be common to all the instances of multicast. stuck.

Answer 1

try

def getResults
        @@groups ||= []
        @@group_name ||= []

instead of

def getResults
        @@groups
        @@group_name

The operator ||= will initialize your variable, but only if it is not already initialized.

And please listen to the comments of Ivan Shamatov about code style and patterns.