adds Budget::Group model to group headings

many refactors through budget related models

app/models/budget.rb

@@ -4,9 +4,11 @@ class Budget < ActiveRecord::Base
 
   validates :phase, inclusion: { in: VALID_PHASES }
 
-  has_many :investments
-  has_many :ballots
-  has_many :headings
+  has_many :investments, dependent: :destroy
+  has_many :ballots, dependent: :destroy
+  has_many :groups, dependent: :destroy
+  has_many :headings, through: :groups
+  has_many :investments, through: :headings
 
   def on_hold?
     phase == "on_hold"
@@ -29,7 +31,6 @@ class Budget < ActiveRecord::Base
   end
 
   def heading_price(heading)
-    return price unless heading.present?
     heading_ids.include?(heading.id) ? heading.price : -1
   end
 end

app/models/budget/ballot.rb

@@ -16,7 +16,7 @@ class Budget
     end
 
     def amount_available(heading)
-      budget.heading_price(heading) - amount_spent(heading.try(:id))
+      budget.heading_price(heading) - amount_spent(heading.id)
     end
   end
 end

app/models/budget/group.rb

@@ -0,0 +1,10 @@
+class Budget
+  class Group < ActiveRecord::Base
+    belongs_to :budget
+
+    has_many :headings, dependent: :destroy
+
+    validates :budget_id, presence: true
+    validates :name, presence: true
+  end
+end

app/models/budget/heading.rb

@@ -1,11 +1,11 @@
 class Budget
   class Heading < ActiveRecord::Base
-    belongs_to :budget
+    belongs_to :group
     belongs_to :geozone
 
     has_many :investments
 
-    validates :budget_id, presence: true
+    validates :group_id, presence: true
     validates :name, presence: true
     validates :price, presence: true
   end

app/models/budget/investment.rb

@@ -10,7 +10,6 @@ class Budget
     acts_as_paranoid column: :hidden_at
     include ActsAsParanoidAliases
 
-    belongs_to :budget
     belongs_to :author, -> { with_hidden }, class_name: 'User', foreign_key: 'author_id'
     belongs_to :heading
     belongs_to :administrator
@@ -43,7 +42,6 @@ class Budget
     scope :with_supports,          -> { where('cached_votes_up > 0') }
 
     scope :by_heading,  -> (heading_id)  { where(heading_id: heading_id) }
-    scope :by_budget,   -> (budget_id)   { where(budget_id: budget_id) }
     scope :by_admin,    -> (admin_id)    { where(administrator_id: admin_id) }
     scope :by_tag,      -> (tag_name)    { tagged_with(tag_name) }
     scope :by_valuator, -> (valuator_id) { where("budget_valuator_assignments.valuator_id = ?", valuator_id).joins(:valuator_assignments) }
@@ -61,8 +59,7 @@ class Budget
     end
 
     def self.scoped_filter(params, current_filter)
-      budget = Budget.find!(params[:budget_id])
-      results = self.by_budget(params[:budget_id])
+      results = budget.investments
       if params[:max_for_no_heading].present? || params[:max_per_heading].present?
         results = limit_results(results, budget, params[:max_per_heading].to_i, params[:max_for_no_heading].to_i)
       end
@@ -118,6 +115,10 @@ class Budget
       where(heading_id: heading == 'all' ? nil : heading.presence)
     end
 
+    def budget
+      heading.group.budget
+    end
+
     def undecided?
       feasibility == "undecided"
     end
@@ -139,7 +140,7 @@ class Budget
     end
 
     def code
-      "B#{budget_id}I#{id}"
+      "B#{budget.id}I#{id}"
     end
 
     def reason_for_not_being_selectable_by(user)