Track member id and username in project user events

Added member id and member user name to properties of
requesting/approving project membership. This change enables us to
compute conversion rate between invited users and users that actually
join project.

Author: iref

lib/code_corps/analytics/segment_traits_builder.ex

@@ -78,10 +78,12 @@ defmodule CodeCorps.Analytics.SegmentTraitsBuilder do
     }
   end
   defp traits(%CodeCorps.ProjectUser{} = record) do
-    record = record |> Repo.preload(:project)
+    record = record |> Repo.preload([:project, :user])
     %{
       project: record.project.title,
-      project_id: record.project_id
+      project_id: record.project_id,
+      member_id: record.user.id,
+      member: record.user.username
     }
   end
   defp traits(%CodeCorps.StripeConnectAccount{} = account) do

test/lib/code_corps_web/controllers/project_user_controller_test.exs

@@ -54,7 +54,9 @@ defmodule CodeCorpsWeb.ProjectUserControllerTest do
 
       tracking_properties = %{
         project: project.title,
-        project_id: project.id
+        project_id: project.id,
+        member: user.username,
+        member_id: user.id
       }
 
       assert_received {:track, ^user_id, "Requested Project Membership", ^tracking_properties}
@@ -106,7 +108,9 @@ defmodule CodeCorpsWeb.ProjectUserControllerTest do
 
       tracking_properties = %{
         project: project.title,
-        project_id: project.id
+        project_id: project.id,
+        member: record.user.username,
+        member_id: record.user.id
       }
 
       assert_received {:track, ^user_id, "Approved Project Membership", ^tracking_properties}