Detect in-place changes on point types

3 files changed, 31 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/cast.rb b/activerecord/lib/active_record/connection_adapters/postgresql/cast.rb
index acc4cdc9e8..a865c5c310 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/cast.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/cast.rb
@@ -3,7 +3,11 @@ module ActiveRecord
     module PostgreSQL
       module Cast # :nodoc:
         def point_to_string(point) # :nodoc:
-          "(#{point[0]},#{point[1]})"
+          "(#{number_for_point(point[0])},#{number_for_point(point[1])})"
+        end
+
+        def number_for_point(number)
+          number.to_s.gsub(/\.0$/, '')
         end
 
         def hstore_to_string(object, array_member = false) # :nodoc:
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/point.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/point.rb
index 9007bfb178..86277c5542 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/point.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/point.rb
@@ -3,20 +3,33 @@ module ActiveRecord
     module PostgreSQL
       module OID # :nodoc:
         class Point < Type::Value
+          include Type::Mutable
+
           def type
             :point
           end
 
           def type_cast(value)
-            if ::String === value
+            case value
+            when ::String
               if value[0] == '(' && value[-1] == ')'
                 value = value[1...-1]
               end
-              value.split(',').map{ |v| Float(v) }
+              type_cast(value.split(','))
+            when ::Array
+              value.map { |v| Float(v) }
             else
               value
             end
           end
+
+          def type_cast_for_database(value)
+            if value.is_a?(::Array)
+              PostgreSQLColumn.point_to_string(value)
+            else
+              super
+            end
+          end
         end
       end
     end
diff --git a/activerecord/test/cases/adapters/postgresql/geometric_test.rb b/activerecord/test/cases/adapters/postgresql/geometric_test.rb
index 2f106ee664..aa737617c4 100644
--- a/activerecord/test/cases/adapters/postgresql/geometric_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/geometric_test.rb
@@ -61,4 +61,15 @@ class PostgresqlPointTest < ActiveRecord::TestCase
     assert record.reload
     assert_equal [1.1, 2.2], record.x
   end
+
+  def test_mutation
+    p = PostgresqlPoint.create! x: [10, 20]
+
+    p.x[1] = 25
+    p.save!
+    p.reload
+
+    assert_equal [10.0, 25.0], p.x
+    assert_not p.changed?
+  end
 end