Add check constraint for users.username (#12741)

db/migrate/20210219043102_add_check_constraint_for_username.rb

@@ -0,0 +1,12 @@
+class AddCheckConstraintForUsername < ActiveRecord::Migration[6.0]
+  def change
+    safety_assured do
+      execute(<<~SQL.squish)
+        ALTER TABLE "users"
+        ADD CONSTRAINT "users_username_not_null"
+        CHECK ("username" IS NOT NULL)
+        NOT VALID
+      SQL
+    end
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2021_02_16_023520) do
+ActiveRecord::Schema.define(version: 2021_02_19_043102) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "citext"