Don't trim excess whitespace in pg #columns_for_distinct

Fixes #16623 introduced by https://github.com/rails/rails/commit/3d5a2019bcccc6fb01bee4811ca669f4383edb51

2 files changed, 10 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 7042817672..6d5270cfc6 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -549,7 +549,8 @@ module ActiveRecord
               # Convert Arel node to string
               s = s.to_sql unless s.is_a?(String)
               # Remove any ASC/DESC modifiers
-              s.gsub(/\s+(?:ASC|DESC)?\s*(?:NULLS\s+(?:FIRST|LAST)\s*)?/i, '')
+              s.gsub(/\s+(?:ASC|DESC)\s*/i, '')
+               .gsub(/\s*NULLS\s+(?:FIRST|LAST)?\s*/i, '')
             }.reject(&:blank?).map.with_index { |column, i| "#{column} AS alias_#{i}" }
 
           [super, *order_columns].join(', ')
diff --git a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
index cfff1f980b..01b3f350b5 100644
--- a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
@@ -334,6 +334,14 @@ module ActiveRecord
           @connection.columns_for_distinct("posts.id", ["posts.created_at desc", "posts.position asc"])
       end
 
+      def test_columns_for_distinct_with_case
+        assert_equal(
+          'posts.id, CASE WHEN author.is_active THEN UPPER(author.name) ELSE UPPER(author.email) END AS alias_0',
+          @connection.columns_for_distinct('posts.id',
+            ["CASE WHEN author.is_active THEN UPPER(author.name) ELSE UPPER(author.email) END"])
+        )
+      end
+
       def test_columns_for_distinct_blank_not_nil_orders
         assert_equal "posts.id, posts.created_at AS alias_0",
           @connection.columns_for_distinct("posts.id", ["posts.created_at desc", "", "   "])