DRY map exporting with policy_scoping

app/controllers/maps_controller.rb

@@ -85,11 +85,24 @@ class MapsController < ApplicationController
                 respond_with(@allmappers, @allmappings, @allsynapses, @alltopics, @allmessages, @map)
             }
             format.json { render json: @map }
-            format.csv { send_data @map.to_csv }
-            format.xls
+            format.csv { redirect_to :export }
+            format.xls { redirect_to :export }
         end
     end
 
+    # GET maps/:id/export
+    def export
+      map = Map.find(params[:id])
+      authorize map
+      exporter = MapExportService(current_user, map)
+      respond_to do |format|
+        format.json { render json: exporter.json }
+        format.csv { send_data exporter.csv }
+        format.xls { @spreadsheet = exporter.xls }
+      end
+    end
+
+
     # GET maps/:id/contains
     def contains
         @map = Map.find(params[:id])

app/models/map.rb

@@ -84,50 +84,6 @@ class Map < ActiveRecord::Base
     json
   end
 
-  def to_spreadsheet
-    spreadsheet = []
-    spreadsheet << ["Topics"]
-    spreadsheet << ["Id", "Name", "Metacode", "X", "Y", "Description", "Link", "User", "Permission"]
-    self.topicmappings.each do |mapping|
-      topic = mapping.mappable
-      next if topic.nil?
-      spreadsheet << [
-        topic.id,
-        topic.name,
-        topic.metacode.name,
-        mapping.xloc,
-        mapping.yloc,
-        topic.desc,
-        topic.link,
-        topic.user.name,
-        topic.permission
-      ]
-    end
-    spreadsheet << []
-    spreadsheet << ["Synapses"]
-    spreadsheet << ["Id", "Description", "Category", "Topic1", "Topic2", "User", "Permission"]
-    self.synapses.each do |synapse|
-      spreadsheet << [
-        synapse.id,
-        synapse.desc,
-        synapse.category,
-        synapse.node1_id,
-        synapse.node2_id,
-        synapse.user.name,
-        synapse.permission
-      ]
-    end
-    spreadsheet
-  end
-
-  def to_csv(options = {})
-    CSV.generate(options) do |csv|
-      to_spreadsheet.each do |line|
-        csv << line
-      end
-    end
-  end
-
   def decode_base64(imgBase64)
     decoded_data = Base64.decode64(imgBase64)
 

app/services/map_export_service.rb

@@ -0,0 +1,84 @@
+class MapExportService < Struct.new(:user, :map)
+  def json
+    # marshal_dump turns OpenStruct into a Hash
+    {
+      topics: exportable_topics.map(:marshal_dump),
+      synapses: exportable_synapses.map(:marshal_dump)
+    }
+  end
+
+  def csv(options = {})
+    CSV.generate(options) do |csv|
+      to_spreadsheet.each do |line|
+        csv << line
+      end
+    end
+  end
+
+  def xls
+    to_spreadsheet
+  end
+
+  private
+
+  def topic_headings
+    [:id, :name, :metacode, :x, :y, :description, :link, :user, :permission]
+  end
+  def synapse_headings
+    [:topic1, :topic2, :category, :description, :user, :permission]
+  end
+
+  def exportable_topics
+    visible_topics ||= Pundit.policy_scope!(@user, @map.topics)
+    topic_mappings = Mapping.includes(mappable: [:metacode, :user])
+                            .where(mappable: visible_topics, map: @map)
+    topic_mappings.map do |mapping|
+      topic = mapping.mappable
+      OpenStruct.new(
+        id: topic.id,
+        name: topic.name,
+        metacode: topic.metacode.name,
+        x: mapping.xloc,
+        y: mapping.yloc,
+        description: topic.desc,
+        link: topic.link,
+        user: topic.user.name,
+        permission: topic.permission
+      )
+    end
+  end
+
+  def exportable_synapses
+    visible_synapses = Pundit.policy_scope!(@user, @map.synapses)
+    visible_synapses.map do |synapse|
+      OpenStruct.new(
+        topic1: synapse.node1_id,
+        topic2: synapse.node2_id,
+        category: synapse.category,
+        description: synapse.desc,
+        user: synapse.user.name,
+        permission: synapse.permission
+      )
+    end
+  end
+
+  def to_spreadsheet
+    spreadsheet = []
+    spreadsheet << ["Topics"]
+    spreadsheet << topic_headings.map(:capitalize)
+    exportable_topics.each do |topics|
+      # convert exportable_topics into an array of arrays
+      topic_headings.map do { |h| topics.send(h) }
+    end
+
+    spreadsheet << []
+    spreadsheet << ["Synapses"]
+    spreadsheet << synapse_headings.map(:capitalize)
+    exportable_synapses.each do |synapse|
+      # convert exportable_synapses into an array of arrays
+      synapse_headings.map do { |h| synapse.send(h) }
+    end
+
+    spreadsheet
+  end
+end

app/views/maps/export.xls.erb

@@ -1,5 +1,5 @@
 <table>
-  <% @map.to_spreadsheet.each do |line| %>
+  <% @spreadsheet.each do |line| %>
     <tr>
       <% line.each do |field| %>
         <td><%= field %></td>

config/routes.rb

@@ -36,6 +36,8 @@ Metamaps::Application.routes.draw do
   get 'topics/:id/relatives', to: 'topics#relatives', as: :relatives
   
   resources :maps, except: [:index, :new, :edit]
+  get 'maps/:id/export', to: 'maps#export'
+
   get 'explore/active', to: 'maps#activemaps'
   get 'explore/featured', to: 'maps#featuredmaps'
   get 'explore/mine', to: 'maps#mymaps'