Make DataOutputAgent use events_order for ordering events in the ou…

…tput

CHANGES.md

@@ -1,5 +1,6 @@
 # Changes
 
+* Jul 22, 2015   - DataOutputAgent can configure the order of events in the output via `events_order`.
 * Jul 20, 2015   - Control Links (used by the SchedularAgent) are correctly exported in Scenarios.
 * Jul 20, 2015   - keep\_events\_for was moved from days to seconds; Scenarios have a schema verison.
 * Jul 1, 2015    - DeDuplicationAgent properly handles destruction of memory.

app/models/agents/data_output_agent.rb

@@ -40,11 +40,15 @@ class DataOutputAgent < Agent
               "_contents": "tag contents (can be an object for nesting)"
             }
 
+        # Ordering events in the output
+
+        #{description_events_order('events in the output')}
+
         # Liquid Templating
 
         In Liquid templating, the following variable is available:
 
-        * `events`: An array of events being output, sorted in descending order up to `events_to_show` in number.  For example, if source events contain a site title in the `site_title` key, you can refer to it in `template.title` by putting `{{events.first.site_title}}`.
+        * `events`: An array of events being output, sorted in the given order, up to `events_to_show` in number.  For example, if source events contain a site title in the `site_title` key, you can refer to it in `template.title` by putting `{{events.first.site_title}}`.
 
       MD
     end
@@ -134,7 +138,7 @@ def receive_web_request(params, method, format)
         end
       end
 
-      source_events = received_events.order(id: :desc).limit(events_to_show).to_a
+      source_events = sort_events(received_events.order(id: :desc).limit(events_to_show).to_a)
 
       interpolation_context.stack do
         interpolation_context['events'] = source_events

spec/models/agents/data_output_agent_spec.rb

@@ -209,6 +209,22 @@
         })
       end
 
+      describe 'ordering' do
+        before do
+          agent.options['events_order'] = ['{{title}}']
+        end
+
+        it 'can reorder the events_to_show last events based on a Liquid expression' do
+          asc_content, _status, _content_type = agent.receive_web_request({ 'secret' => 'secret2' }, 'get', 'application/json')
+          expect(asc_content['items'].map {|i| i["title"] }).to eq(["Evolving", "Evolving again", "Evolving yet again with a past date"])
+
+          agent.options['events_order'] = [['{{title}}', 'string', true]]
+
+          desc_content, _status, _content_type = agent.receive_web_request({ 'secret' => 'secret2' }, 'get', 'application/json')
+          expect(desc_content['items']).to eq(asc_content['items'].reverse)
+        end
+      end
+
       describe "interpolating \"events\"" do
         before do
           agent.options['template']['title'] = "XKCD comics as a feed{% if events.first.site_title %} ({{events.first.site_title}}){% endif %}"