In seeding, actually link to the corresponding objects

Previously, we would pass ids to the creation handler. However, this
does not pass validations whenever the association is non-optional (i.e.
belongs_to). With these changes, we pass the actual Rails objects
instead of just the ids, which does pass the validations and sets it
properly.

db/seeds.rb

@@ -63,6 +63,26 @@ sorted.each do |f, type|
                  # otherwise, no need to worry, just create it
                  [seed]
                 end
+
+        # Transform all _id relations into the actual rails objects to pass validations
+        seeds = seeds.map do |seed|
+          columns = type.column_names.select { |name| name.match(/^.*_id$/) }
+          new_seed = seed.deep_symbolize_keys
+          columns.each do |column|
+            begin
+              column_type_name = column.chomp('_id')
+              column_type = column_type_name.classify.constantize
+              new_seed = new_seed.except(column.to_sym)
+                                 .merge(column_type_name.to_sym => column_type.unscoped.find(seed[column.to_sym]))
+            rescue StandardError
+              # Either the type does not exist or the value specified as the id is not valid, ignore.
+              next
+            end
+          end
+          new_seed
+        end
+
+        # Actually create the objects and count successes
         objs = type.create seeds
         skipped += objs.select { |o| o.errors.any? }.size
         created += objs.select { |o| !o.errors.any? }.size