adds counter cache for assignments

app/models/valuation_assignment.rb

@@ -1,4 +1,4 @@
 class ValuationAssignment < ActiveRecord::Base
   belongs_to :valuator
-  belongs_to :spending_proposal
+  belongs_to :spending_proposal, counter_cache: true
 end

db/migrate/20160225171916_add_assignments_counter_cache_to_spending_proposal.rb

@@ -0,0 +1,5 @@
+class AddAssignmentsCounterCacheToSpendingProposal < ActiveRecord::Migration
+  def change
+    add_column :spending_proposals, :valuation_assignments_count, :integer, default: 0
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160224123110) do
+ActiveRecord::Schema.define(version: 20160225171916) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -308,6 +308,7 @@ ActiveRecord::Schema.define(version: 20160224123110) do
     t.boolean  "valuation_finished",          default: false
     t.text     "explanations_log"
     t.integer  "administrator_id"
+    t.integer  "valuation_assignments_count", default: 0
   end
 
   add_index "spending_proposals", ["author_id"], name: "index_spending_proposals_on_author_id", using: :btree