Add project_key attribute

Project_key will be used to identify projects when
user sends an email to service desk specific address.

changelogs/unreleased/sdesk-name-handler.yml

+---
+title: Added migration which adds project_key column to service_desk_settings.
+merge_request: 24063
+author:
+type: added

db/migrate/20200202100932_add_service_desk_project_key.rb

+# frozen_string_literal: true
+
+class AddServiceDeskProjectKey < ActiveRecord::Migration[5.2]
+  DOWNTIME = false
+
+  def change
+    add_column :service_desk_settings, :project_key, :string, limit: 255
+  end
+end

db/schema.rb

@@ -3797,6 +3797,7 @@ ActiveRecord::Schema.define(version: 2020_02_04_131054) do
   create_table "service_desk_settings", primary_key: "project_id", id: :bigint, default: nil, force: :cascade do |t|
     t.string "issue_template_key", limit: 255
     t.string "outgoing_name", limit: 255
+    t.string "project_key", limit: 255
   end
 
   create_table "services", id: :serial, force: :cascade do |t|

ee/app/models/ee/project.rb

@@ -196,6 +196,12 @@ module EE
         joins('LEFT JOIN services ON services.project_id = projects.id AND services.type = \'GitlabSlackApplicationService\' AND services.active IS true')
           .where('services.id IS NULL')
       end
+
+      def find_by_service_desk_project_key(key)
+        # project_key is not indexed for now
+        # see https://gitlab.com/gitlab-org/gitlab/-/merge_requests/24063#note_282435524 for details
+        joins(:service_desk_setting).find_by('service_desk_settings.project_key' => key)
+      end
     end
 
     def can_store_security_reports?

ee/app/models/service_desk_setting.rb

@@ -7,6 +7,8 @@ class ServiceDeskSetting < ApplicationRecord
   validates :project_id, presence: true
   validate :valid_issue_template
   validates :outgoing_name, length: { maximum: 255 }, allow_blank: true
+  validates :project_key, length: { maximum: 255 }, allow_blank: true, format: { with: /\A[a-z0-9_]+\z/ }
+  validates_uniqueness_of :project_key
 
   def issue_template_content
     strong_memoize(:issue_template_content) do

ee/spec/models/project_spec.rb

@@ -170,6 +170,20 @@ describe Project do
         expect(described_class.with_active_prometheus_service).not_to include(project_without_active_prometheus_service)
       end
     end
+
+    describe '.find_by_service_desk_project_key' do
+      it 'returns the correct project' do
+        project2 = create(:project)
+        create(:service_desk_setting, project: project, project_key: 'key1')
+        create(:service_desk_setting, project: project2, project_key: 'key2')
+
+        expect(Project.find_by_service_desk_project_key('key2')).to eq(project2)
+      end
+
+      it 'returns nil if there is no project with the key' do
+        expect(Project.find_by_service_desk_project_key('some_key')).to be_nil
+      end
+    end
   end
 
   describe 'validations' do

ee/spec/models/service_desk_setting_spec.rb

@@ -4,8 +4,15 @@ require 'spec_helper'
 
 describe ServiceDeskSetting do
   describe 'validations' do
+    subject(:service_desk_setting) { create(:service_desk_setting) }
+
     it { is_expected.to validate_presence_of(:project_id) }
     it { is_expected.to validate_length_of(:outgoing_name).is_at_most(255) }
+    it { is_expected.to validate_length_of(:project_key).is_at_most(255) }
+    it { is_expected.to validate_uniqueness_of(:project_key) }
+    it { is_expected.to allow_value('abc123_').for(:project_key) }
+    it { is_expected.not_to allow_value('abc 12').for(:project_key) }
+    it { is_expected.not_to allow_value('Big val').for(:project_key) }
 
     describe '.valid_issue_template' do
       let_it_be(:project) { create(:project, :custom_repo, files: { '.gitlab/issue_templates/service_desk.md' => 'template' }) }

spec/lib/gitlab/import_export/safe_model_attributes.yml

@@ -783,6 +783,7 @@ ZoomMeeting:
 ServiceDeskSetting:
 - project_id
 - issue_template_key
+- project_key
 ContainerExpirationPolicy:
 - created_at
 - updated_at