Introduce database table for user highest roles

The table stores the highest role for each User they have in a Group
or a Project. If a User has an open invite or pending access request or
no membership the highest role will be set to nil.

app/models/user.rb

@@ -164,6 +164,7 @@ class User < ApplicationRecord
   has_one :status, class_name: 'UserStatus'
   has_one :user_preference
   has_one :user_detail
+  has_one :user_highest_role
 
   #
   # Validations

app/models/user_highest_role.rb

+# frozen_string_literal: true
+
+class UserHighestRole < ApplicationRecord
+  belongs_to :user, optional: false
+
+  validates :highest_access_level, allow_nil: true, inclusion: { in: Gitlab::Access.all_values }
+end

changelogs/unreleased/introduce_highest_role_per_user_database_table.yml

+---
+title: Introduce database table for user highest roles
+merge_request: 26987
+author:
+type: added

db/migrate/20200311093210_create_user_highest_roles.rb

+# frozen_string_literal: true
+
+class CreateUserHighestRoles < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    with_lock_retries do
+      create_table :user_highest_roles, id: false do |t|
+        t.datetime_with_timezone :updated_at, null: false
+        t.references :user, primary_key: true, default: nil, index: false, foreign_key: { on_delete: :cascade }
+        t.integer :highest_access_level
+
+        t.index [:user_id, :highest_access_level]
+      end
+    end
+  end
+
+  def down
+    with_lock_retries do
+      drop_table :user_highest_roles
+    end
+  end
+end

db/schema.rb

@@ -4251,6 +4251,12 @@ ActiveRecord::Schema.define(version: 2020_03_11_165635) do
     t.index ["user_id"], name: "index_user_details_on_user_id", unique: true
   end
 
+  create_table "user_highest_roles", primary_key: "user_id", id: :bigint, default: nil, force: :cascade do |t|
+    t.datetime_with_timezone "updated_at", null: false
+    t.integer "highest_access_level"
+    t.index ["user_id", "highest_access_level"], name: "index_user_highest_roles_on_user_id_and_highest_access_level"
+  end
+
   create_table "user_interacted_projects", id: false, force: :cascade do |t|
     t.integer "user_id", null: false
     t.integer "project_id", null: false
@@ -5135,6 +5141,7 @@ ActiveRecord::Schema.define(version: 2020_03_11_165635) do
   add_foreign_key "user_callouts", "users", on_delete: :cascade
   add_foreign_key "user_custom_attributes", "users", on_delete: :cascade
   add_foreign_key "user_details", "users", on_delete: :cascade
+  add_foreign_key "user_highest_roles", "users", on_delete: :cascade
   add_foreign_key "user_interacted_projects", "projects", name: "fk_722ceba4f7", on_delete: :cascade
   add_foreign_key "user_interacted_projects", "users", name: "fk_0894651f08", on_delete: :cascade
   add_foreign_key "user_preferences", "users", on_delete: :cascade

spec/factories/user_highest_roles.rb

+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :user_highest_role do
+    user
+  end
+end

spec/models/user_highest_role_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe UserHighestRole do
+  describe 'associations' do
+    it { is_expected.to belong_to(:user).required }
+  end
+
+  describe 'validations' do
+    it { is_expected.to validate_inclusion_of(:highest_access_level).in_array([nil, *Gitlab::Access.all_values]) }
+  end
+end

spec/models/user_spec.rb

@@ -30,6 +30,7 @@ describe User, :do_not_mock_admin_mode do
     it { is_expected.to have_one(:status) }
     it { is_expected.to have_one(:max_access_level_membership) }
     it { is_expected.to have_one(:user_detail) }
+    it { is_expected.to have_one(:user_highest_role) }
     it { is_expected.to have_many(:snippets).dependent(:destroy) }
     it { is_expected.to have_many(:members) }
     it { is_expected.to have_many(:project_members) }