Rails42

lib/strong_migrations.rb

@@ -8,11 +8,12 @@
 
 module StrongMigrations
   class << self
-    attr_accessor :auto_analyze, :start_after, :checks, :error_messages
+    attr_accessor :auto_analyze, :start_after, :checks, :error_messages, :ignored
   end
   self.auto_analyze = false
   self.start_after = 0
   self.checks = []
+  self.ignored = []
   self.error_messages = {
     add_column_default:
 "Adding a column with a non-null default causes the entire table to be rewritten.
@@ -39,6 +40,15 @@ def change
   end
 end",
 
+    add_column_default_null:
+      "Adding a column with a null default causes the entire table to be rewritten.
+Instead, add the column without a default value.
+class %{migration_name} < ActiveRecord::Migration%{migration_suffix}
+  def change
+    %{command}
+  end
+end",
+
     add_column_json:
 "There's no equality operator for the json column type, which
 causes issues for SELECT DISTINCT queries. Use jsonb instead.",

lib/strong_migrations/migration.rb

@@ -14,7 +14,7 @@ def migrate(direction)
     end
 
     def method_missing(method, *args, &block)
-      unless @safe || ENV["SAFETY_ASSURED"] || is_a?(ActiveRecord::Schema) || @direction == :down || version_safe?
+      unless @safe || ENV["SAFETY_ASSURED"] || is_a?(ActiveRecord::Schema) || @direction == :down || version_safe? || name_safe?
         ar5 = ActiveRecord::VERSION::MAJOR >= 5
 
         case method
@@ -64,7 +64,10 @@ def method_missing(method, *args, &block)
           options ||= {}
           default = options[:default]
 
-          if !default.nil? && !(postgresql? && postgresql_version >= 110000)
+          if options.key?(:default) && default.nil? && postgresql?
+            raise_error :add_column_default_null,
+              command: command_str("add_column", [table, column, type, options.except(:default)])
+          elsif default && postgresql?
             raise_error :add_column_default,
               add_command: command_str("add_column", [table, column, type, options.except(:default)]),
               change_command: command_str("change_column_default", [table, column, default]),
@@ -149,6 +152,10 @@ def version_safe?
       version && version <= StrongMigrations.start_after
     end
 
+    def name_safe?
+      version.nil? && name && StrongMigrations.ignored.include?(name)
+    end
+
     def raise_error(message_key, header: nil, **vars)
       message = StrongMigrations.error_messages[message_key] || "Missing message"
 

test/strong_migrations_test.rb

@@ -46,6 +46,12 @@ def change
   end
 end
 
+class AddColumnDefaultNull < TestMigration
+  def change
+    add_column :users, :nice, :boolean, default: nil
+  end
+end
+
 class AddColumnDefaultSafe < TestMigration
   def change
     add_column :users, :nice, :boolean
@@ -251,6 +257,10 @@ def test_add_column_default
     assert_unsafe AddColumnDefault
   end
 
+  def test_add_column_default_null
+    assert_unsafe AddColumnDefaultNull
+  end
+
   def test_add_column_default_safe
     assert_safe AddColumnDefaultSafe
   end