Validate dates, times and datetimes for Rails 2.x. Plays nicely with new Rails 2.1 features such as automatic timezone handling and dirty attributes. Allows you to add custom formats or remove defaults easily. This allows you to control what you think should be a valid date or time string.


  • Adds ActiveRecord validation for dates, times and datetimes

  • Add or remove date/time formats to customize validation

  • Create new formats using very simple date/time format tokens

  • Restores ability to see raw value entered for date/time attributes with _before_type_cast modifier, which was lost in Rails 2.1.

  • Supports Rails timezone handling

  • Supports Rails I18n for the error messages

  • Rspec matcher for testing model validation of dates and times


As plugin (from master)

./script/plugin install git://

As gem

sudo gem install validates_timeliness

# in environment.rb

config.gem 'validates_timeliness'


To validate a model with a date, time or datetime attribute you just use the validation method

class Person < ActiveRecord::Base
  validates_date :date_of_birth


The list of validation methods available are as follows:

validates_date     - validate value as date
validates_time     - validate value as time only i.e. '12:20pm'
validates_datetime - validate value as a full date and time

The validation methods take the usual options plus some specific ones to restrict the valid range of dates or times allowed

Temporal options (or restrictions):

:equal_to     - Attribute must be equal to value to be valid
:before       - Attribute must be before this value to be valid
:on_or_before - Attribute must be equal to or before this value to be valid
:after        - Attribute must be after this value to be valid
:on_or_after  - Attribute must be equal to or after this value to be valid
:between      - Attribute must be between the values to be valid. Takes an array of two values or a range

Regular validation options:

:allow_nil    - Allow a nil value to be valid
:allow_blank  - Allows a nil or empty string value to be valid
:if           - Execute validation when :if evaluates true
:unless       - Execute validation when :unless evaluates false

Special options:

:with_time    - Validate a date attribute value combined with a time value against any temporal restrictions
:with_date    - Validate a time attribute value combined with a date value against any temporal restrictions 
:ignore_usec  - Ignores microsecond value on datetime restrictions
:format       - Limit validation to a single format for special cases. Takes plugin format value.

Message options: - Use these to override the default error messages


The temporal restrictions, with_date and with_time can take 4 different value types:

  • String value

  • Date, Time, or DateTime object value

  • Proc or lambda object which may take an optional parameter being the record object

  • A symbol matching the method name in the model

When an attribute value is compared to temporal restrictions, they are compared as the same type as the validation method type. So using validates_date means all values are compared as dates. This is except in the case of with_time and with_date options which effectively force the value to validated as a datetime against the temporal options.


validates_date :date_of_birth :before => lambda { 18.years.ago },
                              :before_message => "must be at least 18 years old"

validates_time :breakfast_time, :on_or_after => '6:00am',
                                :on_or_after_message => 'must be after opening time',
                                :before => :second_breakfast_time,
                                :allow_nil => true

validates_datetime :appointment_date, :before => lambda { 1.week.from_now }

validates_date :entry_date, :with_time => '17:00', :on_or_before => :competition_closing


So what formats does the plugin allow. Well there are default formats which can be added to easily using the plugins format rules. Also formats can be easily removed without hacking the plugin at all.

Below are the default formats. If you think they are easy to read then you will be happy to know that is exactly the format you can use to define your own if you want. No complex regular expressions or duck punching (monkey patching) the plugin is needed.

Time formats:

h nn
h nn_ampm

NOTE: Any time format without a meridian token (the 'ampm' token) is considered in 24 hour time.

Date formats:

m/d/yy  OR  d/m/yy
m\d\yy  OR  d\m\yy
d mmm yy

NOTE: To use non-US date formats see US/EURO FORMATS section

Datetime formats:

m/d/yy h:nn:ss   OR  d/m/yy hh:nn:ss
m/d/yy h:nn      OR  d/m/yy h:nn
m/d/yy h:nn_ampm OR  d/m/yy h:nn_ampm
yyyy-mm-dd hh:nn:ss
yyyy-mm-dd h:nn
ddd mmm d hh:nn:ss zo yyyy # Ruby time string
yyyy-mm-ddThh:nn:ss(?:Z|zo) # ISO 8601

NOTE: To use non-US date formats see US/EURO FORMATS section

Here is what each format token means:

Format tokens:   
     y = year
     m = month
     d = day
     h = hour
     n = minute
     s = second
     u = micro-seconds
  ampm = meridian (am or pm) with or without dots (e.g. am, a.m, or a.m.)
     _ = optional space
    tz = Timezone abbreviation (e.g. UTC, GMT, PST, EST)
    zo = Timezone offset (e.g. +10:00, -08:00, +1000)

Repeating tokens:        
     x = 1 or 2 digits for unit (e.g. 'h' means an hour can be '9' or '09')
    xx = 2 digits exactly for unit (e.g. 'hh' means an hour can only be '09')

Special Cases:
    yy = 2 or 4 digit year
  yyyy = exactly 4 digit year
   mmm = month long name (e.g. 'Jul' or 'July')
   ddd = Day name of 3 to 9 letters (e.g. Wed or Wednesday)
     u = microseconds matches 1 to 3 digits

All other characters are considered literal. For the technically minded (well you are developers), these formats are compiled into regular expressions at runtime so don't add any extra overhead than using regular expressions directly. So, no, it won't make your app slow!

To see all defined formats look in lib/validates_timeliness/formats.rb.


The perenial problem for non-US developers or applications not primarily for the US, is the US date format of m/d/yy. This is ambiguous with the European format of d/m/yy. By default the plugin uses the US formats as this is the Ruby default when it does date interpretation, and is in keeping PoLS (principle of least surprise).

To switch to using the European (or Rest of The World) formats put this in an initializer or environment.rb


Now '01/02/2000' will be parsed as 1st February 2000, instead of 2nd January 2000.


I hear you say “Thats greats but I don't want X format to be valid”. Well to remove a format stick this in an initializer file

ValidatesTimeliness::Formats.remove_formats(:date, 'm\d\yy')

Done! That format is no longer considered valid. Easy!

Ok, now I hear you say “Well I have format that I want to use but you don't have it”. Ahh, then add it yourself. Again stick this in an initializer file

ValidatesTimeliness::Formats.add_formats(:time, "d o'clock")

Now “10 o'clock” will be a valid value. So easy, no more whingeing!

You can embed regular expressions in the format but no gurantees that it will remain intact. If you avoid the use of any token characters and regexp dots or backslashes as special characters in the regexp, it may well work as expected. For special characters use POSIX character classes for safety. See the ISO 8601 datetime for an example of an embedded regular expression.

Because formats are evaluated in order, adding a format which may be ambiguous with an existing format, will mean your format is ignored. If you need to make your new format higher precedence than an existing format, you can include the before option like so

ValidatesTimeliness::Formats.add_formats(:time, 'ss:nn:hh', :before => 'hh:nn:ss')

Now a time of '59:30:23' will be interpreted as 11:30:59 pm. This option saves you adding a new one and deleting an old one to get it to work.


When dealing with 2 digit year values, by default a year is interpreted as being in the last century at or above 30. You can customize this however

ValidatesTimeliness::Formats.ambiguous_year_threshold = 20

Now you get:

year of 19 is considered 2019
year of 20 is considered 1920


Given that Ruby has no support for a time-only type, all time type columns are evaluated as a regular Time class objects with a dummy date value set. Rails defines the dummy date as 2000-01-01. So a time of '12:30' is evaluated as a Time value of '2000-01-01 12:30'. If you need to customize this for some reason you can do so as follows

ValidatesTimeliness::Formats.dummy_date_for_time_type = [2009, 1, 1]

The value should be an array of 3 values being year, month and day in that order.


When using the validation temporal restrictions there are times when the restriction value itself may be invalid. Normally this will add an error to the model such as 'restriction :before value was invalid'. These can be annoying if you are using procs or methods as restrictions and don't care if they don't evaluate properly and you want the validation to complete. In these situations you turn them off.

To turn them off:

ValidatesTimeliness::Validator.ignore_restriction_errors = true

A word of warning though, as this may hide issues with the model and make those corner cases a little harder to test. In general if you are using procs or model methods and you only care when they return a value, then they should return nil in all other situations. Restrictions are skipped if they are nil.


The plugin has some extensions to ActionView and ActiveRecord by allowing invalid date and time values to be redisplayed to the user as feedback, instead of a blank field which happens by default in Rails. Though the date helpers make this a pretty rare occurence, given the select dropdowns for each date/time component, but it may be something of interest.

To activate it, put this in an initializer:



The error messages for each temporal restrictions can also be globally overridden by updating the default AR error messages like so

For Rails 2.0/2.1:

  :invalid_date     => "is not a valid date",
  :invalid_time     => "is not a valid time",
  :invalid_datetime => "is not a valid datetime",
  :before           => "must be before %s",
  :on_or_before     => "must be on or before %s",
  :after            => "must be after %s",
  :on_or_after      => "must be on or after %s",
  :between          => "must be between %s and %s"

Where %s is the interpolation value for the restriction.

Rails 2.2+ using the I18n system to define new defaults:

        on_or_before: "must be equal to or before {{restriction}}"
        on_or_after:  "must be equal to or after {{restriction}}"
        between: "must be between {{earliest}} and {{latest}}"

The {restriction} signifies where the interpolation value for the restriction will be inserted.

And for something a little more specific you can override the format of the interpolation values inserted in the error messages for temporal restrictions like so

For Rails 2.0/2.1:

  :time     => '%H:%M:%S',
  :date     => '%Y-%m-%d',
  :datetime => '%Y-%m-%d %H:%M:%S'

Rails 2.2+ using the I18n system to define new defaults:

    date: '%Y-%m-%d'
    time: '%H:%M:%S'
    datetime: '%Y-%m-%d %H:%M:%S'

Those are Ruby strftime formats not the plugin formats.


To sweeten the deal that little bit more, you have an Rspec matcher available for you model specs. Now you can easily test the validations you have just written with the plugin or better yet before you write them! You just use the validation options you want as you would with the validation method. Those options are then verified and reported if they fail.

First require it in your spec_helper.rb

require 'validates_timeliness/matcher'

Use it like so:

@person.should validate_date(:birth_date, :before =>, :before_message => 'should be before today')

The matcher names are just the singular of the validation methods.



Copyright © 2008 Adam Meehan, released under the MIT license