Railscasts - Validations in Rails 3

#211

Apr 26, 2010

Validations in Rails 3

Rails 3 offers several new additions to validations. Here learn how to make a custom error_messages partial, reflect on validations, and clean up complex validations in a model.

Tags: rails-3.0 forms active-record views

Download (14.4 MB, 9:53)

alternative download for iPod & Apple TV (14.3 MB, 9:53)

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gem install rails --pre
gem cleanup
rails store
cd store
rails g scaffold user name:string email:string
rake db:migrate

<!-- users/_form.html.erb -->
<%= form_for(@user) do |f| %>
  <%= render "shared/error_messages", :target => @user %>
  
  <div class="field">
    <%= f.label :name %><%= mark_required(@user, :name) %><br />
    <%= f.text_field :name %>
  </div>
  <div class="field">
    <%= f.label :email %><%= mark_required(@user, :email) %><br />
    <%= f.text_field :email %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

<!-- shared/_error_messages.html.erb -->
<% if target.errors.any? %>
<div id="errorExplanation">
  <h2><%= pluralize(target.errors.count, "error") %> prohibited this record from being saved:</h2>
  <ul>
  <% target.errors.full_messages.each do |msg| %>
    <li><%= msg %></li>
  <% end %>
  </ul>
</div>
<% end %>

# application_helper.rb
def mark_required(object, attribute)
  "*" if object.class.validators_on(attribute).map(&:class).include? ActiveModel::Validations::PresenceValidator
end

# models/user.rb
validates :email, :presence => true, :uniqueness => true, :email_format => true

# lib/email_format_validator.rb
class EmailFormatValidator < ActiveModel::EachValidator
  def validate_each(object, attribute, value)
    unless value =~ /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i
      object.errors[attribute] << (options[:message] || "is not formatted properly") 
    end
  end
end

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39 comments

1. Rya Apr 26, 2010 at 07:30

Awesome, always looking forward to the Mondays railscast, even if it was late today :)

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2. Ben Apr 26, 2010 at 07:42

Thanks, Awesome as allways :)

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3. Alan Maciel Apr 26, 2010 at 08:14

All new projects in ubernetics will be developed in Rails 3, all this rails 3 series railscasts help me to take this decision.. thanks Ryan!! Rails 3 here we go!!!!

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4. Jon Apr 26, 2010 at 08:57

Really appreciate the good work Ryan. Thanks!!

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5. ryeguy Apr 26, 2010 at 09:01

This video was really glitchy for me -- but all of the past videos have been fine. There were many parts where the frame wouldn't completely be painted when transitioning to a new screen. For example, when switching from the console to the browser, I would still see the console, but could see the cursor kind of "painting" the web browser in. Hard to explain. I think it's encoded poorly. Have you tried using xvid?

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6. ryeguy Apr 26, 2010 at 09:09

To ammend the above, this problem was only when using VLC player. But as I said before, I have never had this problem with any of your other videos.

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7. Ryan Bates Apr 26, 2010 at 09:20

@ryeguy, I'm experimenting with various video codec settings. Were you watching the full resolution or the iPod/AppleTV one?

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8. dpf Apr 26, 2010 at 09:21

same here on the glitchy video. Content is great - but for the first time - the video doesn't update when you've switched views (from textmate to safari for example) for 5 - 10 seconds and is pixelated too.

Thanks Ryan.

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9. Ryan Bates Apr 26, 2010 at 09:22

@dpf, are you using VLC player?

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10. Alan Apr 26, 2010 at 09:23

What would we do without you?

Over the last few episodes I have been convinced that I should be heading in the RoR 3 direction sooner rather than later.

A big 'thank you' Ryan.

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11. dpf Apr 26, 2010 at 09:25

@ryeguy is right - same experience here - the video is fine in totem - but messed up in VLC. Perhaps this isn't worth addressing given the small population of us it effects.

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12. Jamie Hill Apr 26, 2010 at 10:02

Thanks for the summary Ryan. I was the author of "Sexy Validations", you can see my original writeup here: http://thelucid.com/2010/01/08/sexy-validation-in-edge-rails-rails-3/

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13. ryeguy Apr 26, 2010 at 11:08

Ryan - the problem was with the full version of the video. Didn't try the iphone/pod version.

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14. Stefan Huska Apr 26, 2010 at 11:33

Here is my simple RoR plugin for custom error template:

http://github.com/kelso/render_errors

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15. Wlodek Bzyl Apr 26, 2010 at 12:42

If mail is not formatted properly, then the asterisks '*' is rendered between two div's.

Is there a simple way to move '*' into the first div?

<div class="fieldWithErrors"><label for="user_email">Email</label></div>*<br />
<div class="fieldWithErrors"><input id="user_email" name="user[email]" size="30" type="text" value="x" /></div>

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16. KAMiKZ Apr 26, 2010 at 16:00

Great Ep as always Ryan Thanks!

I am on Win7 64bit, VLC does have a problem rendering. Media Player Classic has no problem. And since WMP uses the same codec as does MPC, it plays it fine, as well. Just VLC then.

Regards

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17. At Ryan Bates Apr 26, 2010 at 16:11

Hey rbates, thank you for your useful and awesome casts! Ryan, PLEASE, can you "Build an entire application over a series of screencasts" with Rails 3, where you can cover all other sub-topics like this validation and other devise and etc. Please, do not neglect this comment and make me and people who want to see you build entire apps happy. I would even pay to watch those. Thanks!

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18. Sterling Apr 26, 2010 at 21:15

FYI Ryan: I too have the same issue with the full version using VLC

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19. mario Apr 26, 2010 at 22:58

Video works fine for me on VLC 10.6, Snow Leopard 10.6.3 (as well as in QuickTime)

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20. mario Apr 26, 2010 at 22:58

er, i meant VLC 10.5

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21. Marius Apr 27, 2010 at 04:14

Works under OSX 10.5 with movist.
Works under linux with kaffeine qt4, it doesn't work with smplayer or mplayer.

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22. Bijan Apr 27, 2010 at 06:59

Hey Ryan,

thanks a lot for this episode.
Some time ago I searched for a clever solution and ended up with formtastic in combination with validation reflection. Would you prefer formtastic over this more barebone approach with less abstraction?
For me it is important to get going fast and to have maintainable code I can adjust if I need to.

Kind regards
Bijan

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23. Gang Apr 27, 2010 at 07:10

It's very nice and clean.
Thanks.

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24. Paolo Apr 27, 2010 at 23:40

Thanks again for the new episode.
Ruby-3 seems really wonderful

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25. vladimir prieto Apr 28, 2010 at 06:04

this is the first time video file doesn't play nice. i mean, there were freezed frames all over the cast.

don't know if it is my linux machine (ubuntu 9.10) or the player (vlc).

so, i want to know if you (Ryan) made it in a different way (different kind of codec may be). that way, i could see other alternatives.

thanks.

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26. At Pauolo Apr 28, 2010 at 08:50

@Pauolo

You mean Rails 3?

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27. tobago May 03, 2010 at 09:25

Aaaaawesome!
Having classes of validations is really a step forward.

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28. harris May 05, 2010 at 01:30

i want to know if you (Ryan) made it in a different way (different kind of codec may be). that way, i could see other alternatives.
thanks.<a href="http://www.cissplearn.com">cissp training</a>

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29. SingleSally May 25, 2010 at 07:11

Great stuff, I shall add it to my favourites.

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30. Michaël Rigart May 26, 2010 at 12:51

Nice cast. But one thing that struck me. How do you translate the those validation messages when you use the self made partial as shown in this cast?

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David Heinemeier Hansson

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38. helmerj Jul 27, 2010 at 00:54

The custom validator used here to validate an email address does not work in the just released rc of rails3:

Unknown validator: 'email_format'

So stuff in RAILS_ROOT/lib does nto get loaded I suppose...

Anybody know how to solve this?

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38. helmerj Jul 27, 2010 at 00:59

Well should have done my research properly...

The custom validators have to go here:

app/validators

Cheers J

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40. Ivan Aug 06, 2010 at 08:05

Good post.

But
<%= render :partial => 'shared/error_messages', :target => @user %> does not work for me.
I have "undefined local variable or method `target'" error

So I use
<%= render :partial => 'shared/error_messages', :locals => {:target => @user} %>

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