User#projects_limit remove DB default and added NOT NULL constraint

This change is required because otherwise if a user is created with a
value for `projects_limit` that matches the DB default, it gets
overwritten by `current_application_settings.default_projects_limit`. By
removing the default we once again can allow a user to be created with a
limit of 10 projects without the risk that it'll change to 10000

app/models/user.rb

@@ -794,10 +794,7 @@ class User < ActiveRecord::Base
     # `User.select(:id)` raises
     # `ActiveModel::MissingAttributeError: missing attribute: projects_limit`
     # without this safeguard!
-    return unless has_attribute?(:projects_limit)
-
-    connection_default_value_defined = new_record? && !projects_limit_changed?
-    return unless projects_limit.nil? || connection_default_value_defined
+    return unless has_attribute?(:projects_limit) && projects_limit.nil?
 
     self.projects_limit = current_application_settings.default_projects_limit
   end

changelogs/unreleased/31995-project-limit-default-fix.yml

+---
+title: User#projects_limit remove DB default and added NOT NULL constraint
+merge_request: 16165
+author: Mario de la Ossa
+type: fixed

db/migrate/20171229225929_change_user_project_limit_not_null_and_remove_default.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class ChangeUserProjectLimitNotNullAndRemoveDefault < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  # When a migration requires downtime you **must** uncomment the following
+  # constant and define a short and easy to understand explanation as to why the
+  # migration requires downtime.
+  # DOWNTIME_REASON = ''
+
+  # When using the methods "add_concurrent_index", "remove_concurrent_index" or
+  # "add_column_with_default" you must disable the use of transactions
+  # as these methods can not run in an existing transaction.
+  # When using "add_concurrent_index" or "remove_concurrent_index" methods make sure
+  # that either of them is the _only_ method called in the migration,
+  # any other changes should go in a separate migration.
+  # This ensures that upon failure _only_ the index creation or removing fails
+  # and can be retried or reverted easily.
+  #
+  # To disable transactions uncomment the following line and remove these
+  # comments:
+  # disable_ddl_transaction!
+
+  def up
+    # Set Users#projects_limit to NOT NULL and remove the default value
+    change_column_null :users, :projects_limit, false
+    change_column_default :users, :projects_limit, nil
+  end
+
+  def down
+    change_column_null :users, :projects_limit, true
+    change_column_default :users, :projects_limit, 10
+  end
+end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20171220191323) do
+ActiveRecord::Schema.define(version: 20171229225929) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -1805,7 +1805,7 @@ ActiveRecord::Schema.define(version: 20171220191323) do
     t.datetime "updated_at"
     t.string "name"
     t.boolean "admin", default: false, null: false
-    t.integer "projects_limit", default: 10
+    t.integer "projects_limit", null: false
     t.string "skype", default: "", null: false
     t.string "linkedin", default: "", null: false
     t.string "twitter", default: "", null: false

spec/models/user_spec.rb

@@ -134,6 +134,16 @@ describe User do
       end
     end
 
+    it 'has a DB-level NOT NULL constraint on projects_limit' do
+      user = create(:user)
+
+      expect(user.persisted?).to eq(true)
+
+      expect do
+        user.update_columns(projects_limit: nil)
+      end.to raise_error(ActiveRecord::StatementInvalid)
+    end
+
     it { is_expected.to validate_presence_of(:projects_limit) }
     it { is_expected.to validate_numericality_of(:projects_limit) }
     it { is_expected.to allow_value(0).for(:projects_limit) }
@@ -805,6 +815,13 @@ describe User do
         expect(user.can_create_group).to be_falsey
         expect(user.theme_id).to eq(1)
       end
+
+      it 'does not undo projects_limit setting if it matches old DB default of 10' do
+        # If the real default project limit is 10 then this test is worthless
+        expect(Gitlab.config.gitlab.default_projects_limit).not_to eq(10)
+        user = described_class.new(projects_limit: 10)
+        expect(user.projects_limit).to eq(10)
+      end
     end
 
     context 'when current_application_settings.user_default_external is true' do