Handy Patriawan’s Blog

Update 5/31/2008: Use ActiveSupport::CoreExtensions::Date::Conversions::DATE_FORMATS

I have invested some time to get Rails date validation to work (whoo hoo!).

Without further ado, here are the step by step instructions:
1. Download Rails Date Kit from my site. Note that I got the original kit from http://www.methods.co.nz/rails_date_kit/rails_date_kit.html.
Extract the files in rails_date_kit_1.2.0.tar.gz to <your application>/vendor/plugins/rails_date_kit.

2. Get the Validates Date Time plugin by running the following command in your application directory:

script/plugin install http://svn.viney.net.nz/things/rails/plugins/validates_date_time

You should have a new directory in your <your application>/vendor/plugins/validates_date_time

3. Put the necessary files in the right places.

Copy vendor/plugins/rails_date_kit/calendar.js to public/javascripts
Copy vendor/plugins/rails_date_kit/calendar.css to public/stylesheets
Copy vendor/plugins/rails_date_kit/calendar_prev.png to public/images
Copy vendor/plugins/rails_date_kit/calendar_next.png to public/images
Copy vendor/plugins/rails_date_kit/date_helper.rb to app/helpers

4. Include the css and javascript files for the calendar in your page header (e.g. view/layout/tasks.html.erb):

<%= stylesheet_link_tag ‘calendar.css’ %>
<%= javascript_include_tag ‘calendar’ %>

My application uses application.rhtml, thus I just added the lines there.

5. Create a new file called date_formats.rb in config/initializers. All you need to add is:

ActiveSupport::CoreExtensions::Date::Conversions::DATE_FORMATS.merge!(:default_date => ‘%m/%d/%Y’)

Note the capital Y in ‘%m/%d/%Y’. Obviously, you can add more date formats as needed.
Update: Adjust the date format accordingly to your locale. For example, use ‘%d/%m/%Y’ for displaying date/month/year.

6. Use the following code to add the date field in your input form (e.g. view/tasks/new.html.erb):

<%= date_field :task, :due_date, :format => ActiveSupport::CoreExtensions::Date::Conversions::DATE_FORMATS[:default_date], :value => @task.due_date %>

You can also wrap the whole ‘ActiveSupport::CoreExtensions::Date::Conversions::DATE_FORMATS[:default_date]‘ into a function in app/helpers/application_helper.rb.

6. Tell your model to use en-us date format by adding the following line:

ValidatesDateTime.us_date_format = true #use mm/dd/yyyy format

Update: Set ValidatesDateTime.us_date_format to ‘false’ if your date format is not month/date/year.

7. Validate away!
Here’s an example of my model validation:

Class Task < ActiveRecord::Base
.
.
validates_date :due_date, :allow_nil => true
.
.
End

Enjoy!

Post any questions in the comment.

I had so many junk/test records in my Rails project and thought “hey… rake DB:migrate is a quick way to wipe those records.”

I ran ‘rake db:migrate VERSION=0′ and MySQL was not too happy with me.

Here is the error:

rake aborted!
Mysql::Error: Error on rename of ‘./<database name>/#sql-bb3b_3′ to ‘./<database name>/contexts’ (errno: 150): ALTER TABLE `contexts` DROP `user_id`

Again… Google is my best friend to find these kind of errors.

The problem is caused by database foreign key.

If your migration has the following line:

class MigrationName < ActiveRecord::Migration
def self.up
  .
  .
  execute “alter table <table name> add constraint <foreign key name> foreign key (<column name>) references …”
end

The solution is to drop the foreign key first before removing the column:

def self.down
  execute “alter table <table name> drop foreign key <foreign key name>”
  remove_column …
end