Introduce `Ci::Stage`, right now this is artificial object that is build dynamically.

app/models/ci/pipeline.rb

@@ -100,32 +100,22 @@ module Ci
       where.not(duration: nil).sum(:duration)
     end
 
-    def stages_query
-      statuses.group('stage').select(:stage)
-        .order('max(stage_idx)')
+    def stages_count
+      statuses.select(:stage).distinct.count
     end
 
     def stages
-      self.stages_query.pluck(:stage)
-    end
-
-    def stages_with_statuses
       status_sql = statuses.latest.where('stage=sg.stage').status_sql
 
-      stages_with_statuses = CommitStatus.from(self.stages_query, :sg).
+      stages_query = statuses.group('stage').select(:stage)
+                       .order('max(stage_idx)')
+
+      stages_with_statuses = CommitStatus.from(stages_query, :sg).
         pluck('sg.stage', status_sql)
 
       stages_with_statuses.map do |stage|
-        OpenStruct.new(
-          name: stage.first,
-          status: stage.last,
-          pipeline: self
-        )
-      end
+        Ci::Stage.new(self, stage.first, status: stage.last)
       end
-
-    def stages_with_latest_statuses
-      statuses.latest.includes(project: :namespace).order(:stage_idx).group_by(&:stage)
     end
 
     def artifacts

app/models/ci/stage.rb

+module Ci
+  class Stage < ActiveRecord::Base
+    include ActiveModel::Model
+
+    attr_reader :pipeline, :name
+
+    def initialize(pipeline, name: name, status: status = nil)
+      @pipeline, @name, @status = pipeline, name, status
+    end
+
+    def status
+      @status ||= statuses.latest.status
+    end
+
+    def statuses
+      pipeline.statuses.where(stage: stage)
+    end
+
+    def builds
+      pipeline.builds.where(stage: stage)
+    end
+  end
+end

app/models/commit_status.rb

@@ -41,8 +41,8 @@ class CommitStatus < ActiveRecord::Base
       where("#{quoted_when} <> ? OR status <> ?", 'on_failure', 'skipped')
   end
 
-  scope :latest_ci_stages, -> { latest.ordered.includes(project: :namespace) }
-  scope :retried_ci_stages, -> { retried.ordered.includes(project: :namespace) }
+  scope :latest_ordered, -> { latest.ordered.includes(project: :namespace) }
+  scope :retried_ordered, -> { retried.ordered.includes(project: :namespace) }
 
   state_machine :status do
     event :enqueue do
@@ -117,11 +117,6 @@ class CommitStatus < ActiveRecord::Base
     name.gsub(/\d+[\s:\/\\]+\d+\s*/, '').strip
   end
 
-  def self.stages
-    # We group by stage name, but order stages by theirs' index
-    unscoped.from(all, :sg).group('stage').order('max(stage_idx)', 'stage').select('sg.stage')
-  end
-
   def failed_but_allowed?
     allow_failure? && (failed? || canceled?)
   end

app/views/notify/pipeline_success_email.html.haml

@@ -133,7 +133,7 @@
                         %tr.success-message
                           %td{style: "font-family:'Helvetica Neue',Helvetica,Arial,sans-serif;color:#333333;font-size:15px;font-weight:400;line-height:1.4;padding:15px 5px;text-align:center;"}
                             - build_count = @pipeline.statuses.latest.size
-                            - stage_count = @pipeline.stages.size
+                            - stage_count = @pipeline.stages_count
                             Pipeline
                             %a{href: pipeline_url(@pipeline), style: "color:#3777b0;text-decoration:none;"}
                               = "\##{@pipeline.id}"

app/views/notify/pipeline_success_email.text.erb

@@ -16,7 +16,7 @@ Commit Author: <%= commit.author_name %>
 <% end -%>
 
 <% build_count = @pipeline.statuses.latest.size -%>
-<% stage_count = @pipeline.stages.size -%>
+<% stage_count = @pipeline.stages_count -%>
 Pipeline #<%= @pipeline.id %> ( <%= pipeline_url(@pipeline) %> ) successfully completed <%= build_count %> <%= 'build'.pluralize(build_count) %> in <%= stage_count %> <%= 'stage'.pluralize(stage_count) %>.
 
 You're receiving this email because of your account on <%= Gitlab.config.gitlab.host %>.

app/views/projects/builds/_sidebar.html.haml

@@ -111,7 +111,7 @@
           %span.label.label-primary
             = tag
 
-    - if @build.pipeline.stages.many?
+    - if @build.pipeline.stages_count.many?
       .dropdown.build-dropdown
         .title Stage
         %button.dropdown-menu-toggle{type: 'button', 'data-toggle' => 'dropdown'}

app/views/projects/commit/_ci_stage.html.haml

-%tr
-  %th{colspan: 10}
-    %strong
-      %a{name: stage}
-      - status = statuses.latest.status
-      %span{class: "ci-status-link ci-status-icon-#{status}"}
-        = ci_icon_for_status(status)
-      - if stage
-         
-        = stage.titleize
-  = render statuses.latest_ci_stages, coverage: @project.build_coverage_enabled?, stage: false, ref: false, pipeline_link: false, allow_retry: true
-  = render statuses.retried_ci_stages, coverage: @project.build_coverage_enabled?, stage: false, ref: false, pipeline_link: false, retried: true
-%tr
-  %td{colspan: 10}
-     

app/views/projects/commit/_pipeline.html.haml

@@ -27,16 +27,15 @@
   .row-content-block.build-content.middle-block.pipeline-graph.hidden
     .pipeline-visualization
       %ul.stage-column-list
-        - stages = pipeline.stages_with_latest_statuses
-        - stages.each do |stage, statuses|
+        - pipeline.stages.each do |stage|
           %li.stage-column
             .stage-name
-              %a{name: stage}
-              - if stage
-                = stage.titleize
+              %a{name: stage.name}
+              - if stage.name
+                = stage.name.titleize
             .builds-container
               %ul
-                = render "projects/commit/pipeline_stage", statuses: statuses
+                = render "projects/commit/pipeline_stage", statuses: stage.statuses
 
 
 - if pipeline.yaml_errors.present?
@@ -62,5 +61,4 @@
         - if pipeline.project.build_coverage_enabled?
           %th Coverage
         %th
-    - pipeline.stages.each do |stage|
-      = render 'projects/commit/ci_stage', stage: stage, statuses: pipeline.statuses.relevant.where(stage: stage)
+      = render pipeline.stages

app/views/projects/pipelines/_with_tabs.html.haml

@@ -15,13 +15,12 @@
     .build-content.middle-block.pipeline-graph
       .pipeline-visualization
         %ul.stage-column-list
-          - stages = pipeline.stages_with_latest_statuses
-          - stages.each do |stage, statuses|
+          - pipeline.stages.each do |stage|
             %li.stage-column
               .stage-name
-                %a{name: stage}
-                - if stage
-                  = stage.titleize
+                %a{name: stage.name}
+                - if stage.name
+                  = stage.name.titleize
               .builds-container
                 %ul
                   = render "projects/commit/pipeline_stage", statuses: statuses
@@ -50,5 +49,4 @@
             - if pipeline.project.build_coverage_enabled?
               %th Coverage
             %th
-        - pipeline.statuses.relevant.stages.each do |stage|
-          = render 'projects/commit/ci_stage', stage: stage, statuses: pipeline.statuses.relevant.where(stage: stage)
+        = render pipeline.stages

app/views/projects/pipelines/index.html.haml

@@ -37,7 +37,6 @@
           %span CI Lint
 
   %div.content-list.pipelines
-    - stages = @pipelines.stages
     - if @pipelines.blank?
       %div
         .nothing-here-block No pipelines to show

app/views/projects/stage/_stage.html.haml

+%tr
+  %th{colspan: 10}
+    %strong
+      %a{name: subject.name}
+      %span{class: "ci-status-link ci-status-icon-#{subject.status}"}
+        = ci_icon_for_status(subject.status)
+      - if subject.name
+         
+        = subject.name.titleize
+  = render subject.statuses.latest_ordered, coverage: @project.build_coverage_enabled?, stage: false, ref: false, pipeline_link: false, allow_retry: true
+  = render subject.statuses.retried_ordered, coverage: @project.build_coverage_enabled?, stage: false, ref: false, pipeline_link: false, retried: true
+%tr
+  %td{colspan: 10}
+     

lib/gitlab/data_builder/pipeline.rb

@@ -22,7 +22,7 @@ module Gitlab
           sha: pipeline.sha,
           before_sha: pipeline.before_sha,
           status: pipeline.status,
-          stages: pipeline.stages,
+          stages: pipeline.stages.map(&:name),
           created_at: pipeline.created_at,
           finished_at: pipeline.finished_at,
           duration: pipeline.duration