Allow precision option for MySQL datetimes

activerecord/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Allow precision option for MySQL datetimes.
+
+    *Ryuta Kamizono*
+
 *   Fix `reaping_frequency` option when the value is a string.
 
     This usually happens when it is configured using `DATABASE_URL`.

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -591,6 +591,13 @@ def type_to_sql(type, limit = nil, precision = nil, scale = nil)
           when 0x1000000..0xffffffff; 'longtext'
           else raise(ActiveRecordError, "No text type has character length #{limit}")
           end
+        when 'datetime'
+          return super unless precision
+
+          case precision
+            when 0..6; "datetime(#{precision})"
+            else raise(ActiveRecordError, "No datetime type has precision of #{precision}. The allowed range of precision is from 0 to 6")
+          end
         else
           super
         end
@@ -679,6 +686,11 @@ def initialize_type_map(m) # :nodoc:
         m.alias_type %r(year)i,          'integer'
         m.alias_type %r(bit)i,           'binary'
 
+        m.register_type(%r(datetime)i) do |sql_type|
+          precision = extract_precision(sql_type)
+          Type::DateTime.new(precision: precision)
+        end
+
         m.register_type(%r(enum)i) do |sql_type|
           limit = sql_type[/^enum\((.+)\)/i, 1]
             .split(',').map{|enum| enum.strip.length - 2}.max

activerecord/test/cases/adapters/mysql/datetime_test.rb

@@ -0,0 +1,70 @@
+require 'cases/helper'
+
+if mysql_56?
+  class DateTimeTest < ActiveRecord::TestCase
+
+    def test_default_datetime_precision
+      ActiveRecord::Base.connection.create_table(:foos, force: true)
+      ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime
+      ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime
+      assert_nil activerecord_column_option('foos', 'created_at', 'precision')
+    end
+
+    def test_datetime_data_type_with_precision
+      ActiveRecord::Base.connection.create_table(:foos, force: true)
+      ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime, precision: 1
+      ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime, precision: 5
+      assert_equal 1, activerecord_column_option('foos', 'created_at', 'precision')
+      assert_equal 5, activerecord_column_option('foos', 'updated_at', 'precision')
+    end
+
+    def test_timestamps_helper_with_custom_precision
+      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
+        t.timestamps null: true, precision: 4
+      end
+      assert_equal 4, activerecord_column_option('foos', 'created_at', 'precision')
+      assert_equal 4, activerecord_column_option('foos', 'updated_at', 'precision')
+    end
+
+    def test_passing_precision_to_datetime_does_not_set_limit
+      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
+        t.timestamps null: true, precision: 4
+      end
+      assert_nil activerecord_column_option('foos', 'created_at', 'limit')
+      assert_nil activerecord_column_option('foos', 'updated_at', 'limit')
+    end
+
+    def test_invalid_datetime_precision_raises_error
+      assert_raises ActiveRecord::ActiveRecordError do
+        ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
+          t.timestamps null: true, precision: 7
+        end
+      end
+    end
+
+    def test_mysql_agrees_with_activerecord_about_precision
+      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
+        t.timestamps null: true, precision: 4
+      end
+      assert_equal 4, mysql_datetime_precision('foos', 'created_at')
+      assert_equal 4, mysql_datetime_precision('foos', 'updated_at')
+    end
+
+    private
+
+    def mysql_datetime_precision(table_name, column_name)
+      results = ActiveRecord::Base.connection.exec_query("SELECT column_name, datetime_precision FROM information_schema.columns WHERE table_name ='#{table_name}'")
+      result = results.find do |result_hash|
+        result_hash["column_name"] == column_name
+      end
+      result && result["datetime_precision"]
+    end
+
+    def activerecord_column_option(tablename, column_name, option)
+      result = ActiveRecord::Base.connection.columns(tablename).find do |column|
+        column.name == column_name
+      end
+      result && result.send(option)
+    end
+  end
+end

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

@@ -0,0 +1,70 @@
+require 'cases/helper'
+
+if mysql_56?
+  class DateTimeTest < ActiveRecord::TestCase
+
+    def test_default_datetime_precision
+      ActiveRecord::Base.connection.create_table(:foos, force: true)
+      ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime
+      ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime
+      assert_nil activerecord_column_option('foos', 'created_at', 'precision')
+    end
+
+    def test_datetime_data_type_with_precision
+      ActiveRecord::Base.connection.create_table(:foos, force: true)
+      ActiveRecord::Base.connection.add_column :foos, :created_at, :datetime, precision: 1
+      ActiveRecord::Base.connection.add_column :foos, :updated_at, :datetime, precision: 5
+      assert_equal 1, activerecord_column_option('foos', 'created_at', 'precision')
+      assert_equal 5, activerecord_column_option('foos', 'updated_at', 'precision')
+    end
+
+    def test_timestamps_helper_with_custom_precision
+      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
+        t.timestamps null: true, precision: 4
+      end
+      assert_equal 4, activerecord_column_option('foos', 'created_at', 'precision')
+      assert_equal 4, activerecord_column_option('foos', 'updated_at', 'precision')
+    end
+
+    def test_passing_precision_to_datetime_does_not_set_limit
+      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
+        t.timestamps null: true, precision: 4
+      end
+      assert_nil activerecord_column_option('foos', 'created_at', 'limit')
+      assert_nil activerecord_column_option('foos', 'updated_at', 'limit')
+    end
+
+    def test_invalid_datetime_precision_raises_error
+      assert_raises ActiveRecord::ActiveRecordError do
+        ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
+          t.timestamps null: true, precision: 7
+        end
+      end
+    end
+
+    def test_mysql_agrees_with_activerecord_about_precision
+      ActiveRecord::Base.connection.create_table(:foos, force: true) do |t|
+        t.timestamps null: true, precision: 4
+      end
+      assert_equal 4, mysql_datetime_precision('foos', 'created_at')
+      assert_equal 4, mysql_datetime_precision('foos', 'updated_at')
+    end
+
+    private
+
+    def mysql_datetime_precision(table_name, column_name)
+      results = ActiveRecord::Base.connection.exec_query("SELECT column_name, datetime_precision FROM information_schema.columns WHERE table_name ='#{table_name}'")
+      result = results.find do |result_hash|
+        result_hash["column_name"] == column_name
+      end
+      result && result["datetime_precision"]
+    end
+
+    def activerecord_column_option(tablename, column_name, option)
+      result = ActiveRecord::Base.connection.columns(tablename).find do |column|
+        column.name == column_name
+      end
+      result && result.send(option)
+    end
+  end
+end

activerecord/test/cases/schema_dumper_test.rb

@@ -232,6 +232,13 @@ def test_schema_dumps_index_type
     end
   end
 
+  if mysql_56?
+    def test_schema_dump_includes_datetime_precision
+      output = standard_dump
+      assert_match %r{t.datetime\s+"written_on",\s+precision: 6$}, output
+    end
+  end
+
   def test_schema_dump_includes_decimal_options
     output = dump_all_table_schema([/^[^n]/])
     assert_match %r{precision: 3,[[:space:]]+scale: 2,[[:space:]]+default: 2.78}, output

activerecord/test/schema/schema.rb

@@ -726,7 +726,7 @@ def except(adapter_names_to_exclude)
     t.string   :author_name
     t.string   :author_email_address
     if mysql_56?
-      t.datetime :written_on, limit: 6
+      t.datetime :written_on, precision: 6
     else
       t.datetime :written_on
     end