Merge pull request rails#46110 from sambostock/virtual-datetime-column-precision

Fix erroneous nil default precision on virtual datetime columns

Author: rafaelfranca

activerecord/CHANGELOG.md

@@ -1,3 +1,17 @@
+*   Fix erroneous nil default precision on virtual datetime columns.
+
+    Prior to this change, virtual datetime columns did not have the same
+    default precision as regular datetime columns, resulting in the following
+    being erroneously equivalent:
+
+        t.virtual :name, type: datetime,                 as: "expression"
+        t.virtual :name, type: datetime, precision: nil, as: "expression"
+
+    This change fixes the default precision lookup, so virtual and regular
+    datetime column default precisions match.
+
+    *Sam Bostock*
+
 *   Use connection from `#with_raw_connection` in `#quote_string`.
 
     This ensures that the string quoting is wrapped in the reconnect and retry logic

activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb

@@ -475,12 +475,6 @@ def column(name, type, index: nil, **options)
           end
         end
 
-        if @conn.supports_datetime_with_precision?
-          if type == :datetime && !options.key?(:precision)
-            options[:precision] = 6
-          end
-        end
-
         @columns_hash[name] = new_column_definition(name, type, **options)
 
         if index
@@ -547,6 +541,13 @@ def new_column_definition(name, type, **options) # :nodoc:
           type = integer_like_primary_key_type(type, options)
         end
         type = aliased_types(type.to_s, type)
+
+        if @conn.supports_datetime_with_precision?
+          if type == :datetime && !options.key?(:precision)
+            options[:precision] = 6
+          end
+        end
+
         options[:primary_key] ||= type == :primary_key
         options[:null] = false if options[:primary_key]
         create_column_definition(name, type, options)

activerecord/test/cases/adapters/mysql2/virtual_column_test.rb

@@ -15,12 +15,14 @@ class VirtualColumn < ActiveRecord::Base
     def setup
       @connection = ActiveRecord::Base.connection
       @connection.create_table :virtual_columns, force: true do |t|
-        t.string  :name
-        t.virtual :upper_name,  type: :string,  as: "UPPER(`name`)"
-        t.virtual :name_length, type: :integer, as: "LENGTH(`name`)", stored: true
-        t.virtual :name_octet_length, type: :integer, as: "OCTET_LENGTH(`name`)", stored: true
-        t.json    :profile
-        t.virtual :profile_email, type: :string, as: "json_extract(`profile`,_utf8mb4'$.email')", stored: true
+        t.string   :name
+        t.virtual  :upper_name,  type: :string,  as: "UPPER(`name`)"
+        t.virtual  :name_length, type: :integer, as: "LENGTH(`name`)", stored: true
+        t.virtual  :name_octet_length, type: :integer, as: "OCTET_LENGTH(`name`)", stored: true
+        t.json     :profile
+        t.virtual  :profile_email, type: :string, as: "json_extract(`profile`,_utf8mb4'$.email')", stored: true
+        t.datetime :time
+        t.virtual  :time_mirror, type: :datetime, as: "`time`"
       end
       VirtualColumn.create(name: "Rails")
     end
@@ -61,6 +63,7 @@ def test_schema_dumping
       assert_match(/t\.virtual\s+"name_length",\s+type: :integer,\s+as: "(?:octet_length|length)\(`name`\)",\s+stored: true$/i, output)
       assert_match(/t\.virtual\s+"name_octet_length",\s+type: :integer,\s+as: "(?:octet_length|length)\(`name`\)",\s+stored: true$/i, output)
       assert_match(/t\.virtual\s+"profile_email",\s+type: :string,\s+as: "json_extract\(`profile`,\w*?'\$\.email'\)", stored: true$/i, output)
+      assert_match(/t\.virtual\s+"time_mirror",\s+type: :datetime,\s+as: "`time`"$/i, output[/^.*time_mirror.*$/])
     end
   end
 end

activerecord/test/cases/migration/change_schema_test.rb

@@ -286,7 +286,7 @@ def test_add_column_with_timestamp_type
         elsif current_adapter?(:OracleAdapter)
           assert_equal "TIMESTAMP(6)", column.sql_type
         else
-          assert_equal connection.type_to_sql("datetime"), column.sql_type
+          assert_equal connection.type_to_sql("datetime(6)"), column.sql_type
         end
       end