add context_id and context_type to wiki pages

and populate it; shouldn't do anything yet but
next release we can switch over to direct associations

refs #CNVS-38247

Change-Id: I23e0983d5be61d45db8087738f658b63dc0aeb48
Reviewed-on: https://gerrit.instructure.com/119253
Tested-by: Jenkins
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>

app/models/wiki_page.rb

@@ -55,6 +55,8 @@ class WikiPage < ActiveRecord::Base
     if: proc { self.context.try(:feature_enabled?, :conditional_release) }
   before_save :set_revised_at
   before_validation :ensure_unique_title
+
+  before_save :ensure_context
   after_save  :touch_wiki_context
   after_save  :update_assignment,
     if: proc { self.context.try(:feature_enabled?, :conditional_release) }
@@ -86,6 +88,13 @@ class WikiPage < ActiveRecord::Base
   TITLE_LENGTH = 255
   SIMPLY_VERSIONED_EXCLUDE_FIELDS = [:workflow_state, :editing_roles, :notify_of_update].freeze
 
+  def ensure_context
+    # TODO: get rid of once all existing wiki pages have their context populated and wiki page creation methods can be rewritten
+    # e.g. course.wiki.wiki_pages.create -> course.wiki_pages.create
+    self.context_type ||= self.context.class.base_class.name
+    self.context_id ||= self.context.id
+  end
+
   def touch_wiki_context
     self.wiki.touch_context if self.wiki && self.wiki.context
   end

db/migrate/20170714191148_add_context_to_wiki_pages.rb

@@ -0,0 +1,10 @@
+class AddContextToWikiPages < ActiveRecord::Migration[5.0]
+  disable_ddl_transaction!
+  tag :predeploy
+
+  def change
+    add_column :wiki_pages, :context_id, :integer, :limit => 8
+    add_column :wiki_pages, :context_type, :string
+    add_index :wiki_pages, [:context_id, :context_type], algorithm: :concurrently
+  end
+end

db/migrate/20170714192323_populate_context_on_wiki_pages.rb

@@ -0,0 +1,8 @@
+class PopulateContextOnWikiPages < ActiveRecord::Migration[5.0]
+  tag :postdeploy
+
+  def change
+    DataFixup::PopulateContextOnWikiPages.send_later_if_production_enqueue_args(:run,
+      :priority => Delayed::LOW_PRIORITY, :strand => "populate_wiki_page_context_#{Shard.current.database_server.id}")
+  end
+end

lib/data_fixup/populate_context_on_wiki_pages.rb

@@ -0,0 +1,8 @@
+module DataFixup::PopulateContextOnWikiPages
+  def self.run
+    WikiPage.find_ids_in_ranges do |min_id, max_id|
+      WikiPage.where(:id => min_id..max_id, :context_id => nil).joins(:wiki => :course).update_all("context_type='Course', context_id=courses.id")
+      WikiPage.where(:id => min_id..max_id, :context_id => nil).joins(:wiki => :group).update_all("context_type='Group', context_id=groups.id")
+    end
+  end
+end

spec/models/context_module_spec.rb

@@ -186,8 +186,8 @@ describe ContextModule do
     it "should not add invalid wiki pages" do
       course_module
       @course.wiki
-      @wiki = Wiki.create!(:title => "new wiki")
+      other_course = Account.default.courses.create!
-      @page = @wiki.wiki_pages.create!(:title => "new page")
+      @page = other_course.wiki.wiki_pages.create!(:title => "new page")
       @tag = @module.add_item({:id => @page.id, :type => 'wiki_page'})
       expect(@tag).to be_nil
     end