Make `_before_type_cast` actually be before type cast

- The following is now true for all types, all the time
  - `model.attribute_before_type_cast == given_value`
  - `model.attribute == model.save_and_reload.attribute`
  - `model.attribute == model.dup.attribute`
  - `model.attribute == YAML.load(YAML.dump(model)).attribute`
- Removes the remaining types implementing `type_cast_for_write`
- Simplifies the implementation of time zone aware attributes
- Brings tz aware attributes closer to being implemented as an attribute
  decorator
- Adds additional point of control for custom types

3 files changed, 7 insertions, 1 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/composite_test.rb b/activerecord/test/cases/adapters/postgresql/composite_test.rb
index a925263098..0b48fe9af8 100644
--- a/activerecord/test/cases/adapters/postgresql/composite_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/composite_test.rb
@@ -90,7 +90,11 @@ class PostgresqlCompositeWithCustomOIDTest < ActiveRecord::TestCase
       end
     end
 
-    def type_cast_for_write(value)
+    def type_cast_from_user(value)
+      value
+    end
+
+    def type_cast_for_database(value)
       return if value.nil?
       "(#{value.city},#{value.street})"
     end
diff --git a/activerecord/test/cases/adapters/postgresql/hstore_test.rb b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
index a6482786c7..0b8c9fc052 100644
--- a/activerecord/test/cases/adapters/postgresql/hstore_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
@@ -106,6 +106,7 @@ class PostgresqlHstoreTest < ActiveRecord::TestCase
 
     def test_cast_value_on_write
       x = Hstore.new tags: {"bool" => true, "number" => 5}
+      assert_equal({"bool" => true, "number" => 5}, x.tags_before_type_cast)
       assert_equal({"bool" => "true", "number" => "5"}, x.tags)
       x.save
       assert_equal({"bool" => "true", "number" => "5"}, x.reload.tags)
diff --git a/activerecord/test/cases/adapters/postgresql/json_test.rb b/activerecord/test/cases/adapters/postgresql/json_test.rb
index 61d4e2b8ae..eab6049956 100644
--- a/activerecord/test/cases/adapters/postgresql/json_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/json_test.rb
@@ -68,6 +68,7 @@ class PostgresqlJSONTest < ActiveRecord::TestCase
 
   def test_cast_value_on_write
     x = JsonDataType.new payload: {"string" => "foo", :symbol => :bar}
+    assert_equal({"string" => "foo", :symbol => :bar}, x.payload_before_type_cast)
     assert_equal({"string" => "foo", "symbol" => "bar"}, x.payload)
     x.save
     assert_equal({"string" => "foo", "symbol" => "bar"}, x.reload.payload)