Change sqlite3 boolean serialization to use 1 and 0

Abstract boolean serialization has been using 't' and 'f', with MySQL
overriding that to use 1 and 0.

This has the advantage that SQLite natively recognizes 1 and 0 as true
and false, but does not natively recognize 't' and 'f'.

This change in serialization requires a migration of stored boolean data
for SQLite databases, so it's implemented behind a configuration flag
whose default false value is deprecated. The flag itself can be
deprecated in a future version of Rails.  While loaded models will give
the correct result for boolean columns without migrating old data,
where() clauses will interact incorrectly with old data.

While working in this area, also change the abstract adapter to use
`"TRUE"` and `"FALSE"` as quoted values and `true` and `false` for
unquoted.  These are supported by PostreSQL, and MySQL remains
overriden.

3 files changed, 36 insertions, 0 deletions

diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index d403c4fa7c..4797223380 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -86,6 +86,10 @@ module Rails
 
           if respond_to?(:active_record)
             active_record.cache_versioning = true
+            # Remove the temporary load hook from SQLite3Adapter when this is removed
+            ActiveSupport.on_load(:active_record_sqlite3adapter) do
+              ActiveRecord::ConnectionAdapters::SQLite3Adapter.represent_boolean_as_integer = true
+            end
           end
 
           if respond_to?(:action_dispatch)
diff --git a/railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults_5_2.rb.tt b/railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults_5_2.rb.tt
index 900e18251c..f2df0d1e9f 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults_5_2.rb.tt
+++ b/railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults_5_2.rb.tt
@@ -21,3 +21,7 @@
 # Add default protection from forgery to ActionController::Base instead of in
 # ApplicationController.
 # Rails.application.config.action_controller.default_protect_from_forgery = true
+
+# Store boolean values are in sqlite3 databases as 1 and 0 instead of 't' and
+# 'f' after migrating old data.
+# ActiveRecord::ConnectionAdapters::SQLite3Adapter.represent_boolean_as_integer = true
diff --git a/railties/test/application/configuration_test.rb b/railties/test/application/configuration_test.rb
index 6c0c087331..b8a19379e0 100644
--- a/railties/test/application/configuration_test.rb
+++ b/railties/test/application/configuration_test.rb
@@ -1585,6 +1585,34 @@ module ApplicationTests
       assert_equal({}, Rails.application.config.my_custom_config)
     end
 
+    test "default SQLite3Adapter.represent_boolean_as_integer for 5.1 is false" do
+      remove_from_config '.*config\.load_defaults.*\n'
+      add_to_top_of_config <<-RUBY
+        config.load_defaults 5.1
+      RUBY
+      app_file "app/models/post.rb", <<-RUBY
+        class Post < ActiveRecord::Base
+        end
+      RUBY
+
+      app "development"
+      Post.object_id # force lazy load hooks to run
+
+      assert_not ActiveRecord::ConnectionAdapters::SQLite3Adapter.represent_boolean_as_integer
+    end
+
+    test "default SQLite3Adapter.represent_boolean_as_integer for new installs is true" do
+      app_file "app/models/post.rb", <<-RUBY
+        class Post < ActiveRecord::Base
+        end
+      RUBY
+
+      app "development"
+      Post.object_id # force lazy load hooks to run
+
+      assert ActiveRecord::ConnectionAdapters::SQLite3Adapter.represent_boolean_as_integer
+    end
+
     test "config_for containing ERB tags should evaluate" do
       app_file "config/custom.yml", <<-RUBY
       development: