I have two models :

class Project < ActiveRecord::Base
  has_many :ticket
  attr_accessible ....
end

class Ticket < ActiveRecord::Base
  belongs_to :project
  attr_accessible done_date, description, ....
end

In my ProjectsController I would like to create a two dimensional hash to get in one variable for one project all tickets that are done (with done_date as key and description as value).

For example i would like a hash like this :

What i'm looking for :
@tickets_of_project = ["done_date_1" => ["a", "b", "c"], "done_date_2" => ["d", "e"]]

And what i'm currently trying (in ProjectsController) ...

def show
    # Get current project
    @project = Project.find(params[:id])

    # Get all dones tickets for a project, order by done_date
    @tickets = Ticket.where(:project_id => params[:id]).where("done_date IS NOT NULL").order(:done_date)

    # Create a new hash
    @tickets_of_project = Hash.new {}

    # Make a loop on all tickets, and want to complete my hash
    @tickets.each do |ticket|
        # TO DO
        #HOW TO PUT ticket.value IN "tickets_of_project" WITH KEY = ticket.done_date ??**
    end
end

I don't know if i'm in a right way or not (maybe use .map instead of make a where query), but how can I complete and put values in hash by checking index if already exist or not ?

Thanx :)