PostgreSQL, register custom domains. Closes #14305.

This patch registers custom domains in our OID-type_map.
They will behave exactly as the type specified by `pg_type.typbasetype`.

/cc @matthewd

1 files changed, 53 insertions, 0 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/domain_test.rb b/activerecord/test/cases/adapters/postgresql/domain_test.rb
new file mode 100644
index 0000000000..fdf5ce974d
--- /dev/null
+++ b/activerecord/test/cases/adapters/postgresql/domain_test.rb
@@ -0,0 +1,53 @@
+# -*- coding: utf-8 -*-
+require "cases/helper"
+require 'active_record/base'
+require 'active_record/connection_adapters/postgresql_adapter'
+
+class PostgresqlDomainTest < ActiveRecord::TestCase
+  class PostgresqlDomain < ActiveRecord::Base
+    self.table_name = "postgresql_domains"
+  end
+
+  def setup
+    # reset connection to bust all cached statement plans
+    connection_spec = ActiveRecord::Base.remove_connection
+    ActiveRecord::Base.establish_connection(connection_spec)
+
+    @connection = ActiveRecord::Base.connection
+    @connection.transaction do
+      @connection.execute "CREATE DOMAIN custom_money as numeric(8,2)"
+      @connection.create_table('postgresql_domains') do |t|
+        t.column :price, :custom_money
+      end
+    end
+
+    # reload type map after creating the enum type
+    @connection.send(:reload_type_map)
+  end
+
+  teardown do
+    @connection.execute 'DROP TABLE IF EXISTS postgresql_domains'
+    @connection.execute 'DROP DOMAIN IF EXISTS custom_money'
+  end
+
+  def test_column
+    column = PostgresqlDomain.columns_hash["price"]
+    assert_equal :decimal, column.type
+    assert_equal "custom_money", column.sql_type
+    assert column.number?
+    assert_not column.text?
+    assert_not column.binary?
+    assert_not column.array
+  end
+
+  def test_domain_acts_like_basetype
+    PostgresqlDomain.create price: ""
+    record = PostgresqlDomain.first
+    assert_nil record.price
+
+    record.price = "34.15"
+    record.save!
+
+    assert_equal BigDecimal.new("34.15"), record.reload.price
+  end
+end