ActiveRecord: Store Milliseconds (or Microseconds) in Timestamps/Datetimes with Rails / MySQL

add_milliseconds_to_mysql_and_activerecord_timestamps.md

ActiveRecord: Store Milliseconds (or Microseconds) in Timestamps with Rails / MySQL

Milliseconds in your Timestamps.

We got 'em, you want 'em.

Why

Shit needs to be PRECISE

LICENSE

MIT

milliseconds_migration.rb

class MillisecondsMigration < ActiveRecord::Migration
  # Include non default date stamps here
  # Key   :table_name
  # value [:column_names]
  # NOTE: only MySQL 5.6.4 and above supports DATETIME's with more precision than a second.
  TABLES_AND_COLUMNS =  {
    # Your :table_names here
  }
  
  STANDARD_ACTIVE_RECORD_COLUMNS = [:created_at, :updated_at]
  
  TABLE_AND_COLUMNS.each {|k,v| v.concat(STANDARD_ACTIVE_RECORD_COLUMNS)}
  
  def up
    TABLE_AND_COLUMNS.each do |table, columns|
      columns.each do |column|
        # MySQL supports time precision down to microseconds -- DATETIME(6)
        change_column table, column, :datetime, limit: 3
      end
    end
  end

  def down
    TABLE_AND_COLUMNS.each do |table, columns|
      columns.each do |column|
        echange_column table, column, :datetime
      end
    end
  end
end

time.rb

# Save this in config/initializers/WHATEVER.rb
class Time
  # Ruby will complain that it has already initialzed DATE_FORMATS because it has...
  DATE_FORMATS = {
    # Where 3N is the number of places after the decimal (.)
    # If you want microseconds change 3N to 6N
    :db => '%Y-%m-%d %H:%M:%S.%3N'
  }
end

6 is working fine but if i keep 3 I am getting this error

ActiveRecord::StatementInvalid: Mysql2::Error: Incorrect datetime value: '2025-02-16 18:11:59.751.751251' for column 'created_at' at row 1