Calculate vote share in multi-member districts better #19

app.rb

@@ -259,6 +259,15 @@ get '/bodies/:body/elections/:date/:districts_name/:district' do
   @districts_in_this_election = @election.candidacies.districts
   @poll =         Poll.get(@district.id, @election.id)
 
+  if @total_seats == 1
+    @share_denominator = @total_votes
+  elsif @poll.valid_ballot_papers
+    @share_denominator = @poll.valid_ballot_papers
+  else
+    @share_denominator = @total_votes / @total_seats
+    @share_message = "The vote share calculations have been estimated as we do not have data for the number of valid ballot papers in this poll."
+  end
+
   # Postgres: All the columns selected when using GROUP BY must either be aggregate functions or appear in the GROUP BY clause
   @results_by_party = repository(:default).adapter.select("
     SELECT 
@@ -292,7 +301,7 @@ get '/bodies/:body/elections/:date/:districts_name/:district' do
           c.candidate.short_name,
           party_name(c.labcoop, c.party.name),
           commify(c.votes),
-          format_percent(c.votes.to_f / @total_votes * 100),
+          format_percent(c.votes.to_f / @share_denominator * 100),
           c.seats == 1 ? 'Elected' : ''
         ]
     end

models.rb

@@ -18,10 +18,18 @@ class Poll
   end
 
   def total_rejected_ballots
-    @rejected_no_official_mark + \
-    @rejected_too_many_candidates + \
-    @rejected_identifiable_voter + \
-    @rejected_blank_or_uncertain
+    if @rejected_no_official_mark
+      @rejected_no_official_mark + \
+      @rejected_too_many_candidates + \
+      @rejected_identifiable_voter + \
+      @rejected_blank_or_uncertain
+    else
+      nil
+    end
+  end
+
+  def valid_ballot_papers
+    self.total_rejected_ballots ? @ballot_papers_issued - self.total_rejected_ballots : nil
   end
 
   belongs_to :election

views/resultsdistrict.haml

@@ -64,7 +64,7 @@
         = party_name(candidacy.labcoop, candidacy.party.name)
       - if @election_held
         %td.right= commify(candidacy.votes)
-        %td.right= format_percent(candidacy.votes.to_f / @total_votes * 100)
+        %td.right= format_percent(candidacy.votes.to_f / @share_denominator * 100)
           
         - if candidacy.seats == 1
           %td.elected="Elected"
@@ -84,6 +84,10 @@
     %td  
     %td  
 
+- if @share_message
+  .warning
+    = @share_message
+
 %p
   %a{ :href => "?wiki=dokuwiki" }
     DokuWiki