Thank you! Your work is always appreciated!

another brilliant tutorial :) thanks Ryan

Nice. :)

Thanks Ryan. Very goog job!
Can I suggest another screencast related to this one?
I really appreciate something like this with MongoMapper?
The surveys sample fits very well with the concept of a document database.
Is it possible?
Thank you very much.

I've heard this can work somewhat for has many through, but I've not seen a concrete example. Is that what part 2 might be?

Thanks for this Ryan, looking forward to this series.

As it happens I am near completion of a survey website in which I am making use of nested model forms.

I came across a painful bug in the version of rails which I am using (2.3.4):
Check boxes used for data entry (e.g. a boolean value in my model) cause the hashes in params to be split for nested models when the user ticks them.

For example I have a form which includes a nested model called "CourseOffering".
When the user does not tick any check boxes the params hash includes a course_offerings_attributes hash which itself contains one hash for each course offering (as you would expect).
When they do tick a check box, that particular course offering gets split into two different hashes, this causes various problems depending on validation rules.

The only way I was able to overcome this problems was to use select boxes instead.

I hope I have explained this clearly enough - I think it's something to watch out for!

Great screencast, I look forward to the next episode!

Thanks for another quality screencast! Your effort is always appreciated!

We are looking forward to see part 2

Nested model forms are really helpful, I use them right now to add some generic attributes to different models with a has_one relationship. I am wonder how to add these javascript add / remove links though, it seemed not so easy last time I searched for a solution.

Thank you. I've learn a lot with your casts :)

Really happy to see updated screencasts for nested forms. Thanks for all your hard work.

Just luv nested model forms, great cast. Looking forward to see the next parts!

using latest nifty_generators, in the survey model i see the following, but it's not in the railscast:

attr_accessible :name

unless i comment this out, cannot edit questions/answers

Does accepts_nested_attributes_for work well with virtual attributes?

As always, excellent Ryan. I've been a heavy user of the complex forms method, this looks way smarter.

Thanks Ryan! Can't wait Part 2 ;) BTW what is the TextMate plugin you use for creating partials? I can't find one working. Same thing with the one putting links to TextMate when an error occurs, couldn't make it work (this is a Rails plugin, not a TM).

Awesome timing. I just had to do this in a project and wasn't 100% sure I was doing it properly. This just confirmed it for me!

Thanks!

Hello Ryan,

Thank you for yet another awesome cast!

BTW, how are you filling the forms with a touch/click? Which plugin/tool are you using for that?

Thank you!

Paddy

Great stuff Ryan!
Try looking into LowPro for Prototype to create a nested behavior JS class (andd/remove links). It makes your JS code very reusable (http://bit.ly/76dDzz) and there is a version of LowPro for jQuery. And if anyone cares, RightJS comes with most of the functionality built in ;)

Superb. You have raised the screencast quality bar to a new level.
I really love how your increasing mastery of the art is expressed by the emergence of a subtle humor: the finger snap, the answer to the universe... I follow your casts to learn, obviously, but beyond pure information I find them enjoyable because of the sense of being spoken to directly. I'm so impressed.

It's amazing how often these screencasts come out just as I'm trying to figure out how something works.

Specifically, the reject_if was something I was wondering how to implement for today. Thanks for saving me a few hours! :-)

lambda? what was that?

Would it be possible in a future show to also give an example of how to ask questions that are dependent on the answer. Like: if answer == 2
then ask these 4 questions, etc.?

Thanks.
Great Screencasts!!!!

-Luis.

You're a day late with this - I spent hours yesterday trying to figure this out! I really look forward to part two.

Something wrong with cancan? Your "Report as Spam" links don't work anymore and opening them in a new window gives me a "Not authorized to access this page." message.

If I may suggest a cast topic: could you do a cast on testing models with associations and sessions? I find this really troublesome. My app works, but a lot of tests fail, because some objects turn out to be nil. I have nailed this down to sessions not working so well. I have found a snippet of yours in some forum, but this doesn't help. Well, it did help, but sometimes it doesn't. Very strange...

Last, but not least: Thanks for all those great screencasts. :-)

This is a great update to one of my most-referenced railscasts! So glad to see the multiple nesting and how much easier it has become in Rails 2.3!

Does anyone know if formtastic supports nested models?

Yes, formtastic supports nested models.

It's in the documentation.

http://github.com/justinfrench/formtastic

Interesting. I was unable to get this functionality working in formtastic.

I'll try again, mimicing Ryan's code.

Thanks!

Exactly what I needed, exactly when I needed it. Thanks, Ryan. Looking forward to Part Deux.

Will you do a railscast about the plugin you use for the snapping of the fingers? :)

P.S. This cast is my favourite! Can't wait until next week.

Thank you Ryan for another series of screencasts!

Hopefully this time you will cover long-awaited validation in deeply nested forms.

Thanks a MILLION,
Boris

You are amazing Ryan! I was just bashing my head in the other day wondering how to pull this off with my controllers spazzing out at one another. Not the best task for a newb.

It's trippy how you always seem to find what I need at the right time.

Thanks

I guess it's not _destroy but _delete. The _destroy was not working for me and I looked at railsbrain.com and it was actually _delete.

http://railsbrain.com/api/rails-2.3.2/doc/index.html?a=M002182&name=accepts_nested_attributes_for

really nice tutorial, looking forward for part two. Also interested in deleting and sorting elements using js

Thanks Ryan! Great tutorial, as I was struggling in a project with many nested models.

For some reason, I can't get this to work:

:reject_if => lambda { |a| a[:content].blank? }

It simply won't save the questions to the database. Anyone else having that issue?

If I remove it, the questions are saved but blank ones are saved as well - just as in the screencast prior to adding that line to Ryan's controller.

Ah, it seems to be an issue with passing in the content as a symbol. If I do it like this it works fine:

:reject_if => lambda { |a| a['content'].blank? }

Can anyone help me understand why?

@Chris Lerum you need to do give the nested_attribute free:
attr_accessible :questions_attributes

Great screencast, Ryan. I found myself using the Complex Form series quite a lot in my work. I am loving passing these as attributes so easily.

I did wonder about a TextMate-ism in your railscast. I noticed once you made your partial you were able to start at "builder." and select up to builder on multiple lines and then used a key combo to select only "builder" in order to change all instances to "f". Is that a custom item in a bundle or is it available and I just don't know about it?

I did notice some updates already with Rails 2.3.5.

1. _destroy has been changed to _delete
2. a[:content] is not recognizing the string representation of content, so it must be a['content']

I am loving the new changes and can't wait till Part 2!

Yet another fantastic railscast, I am looking forward to the follow up - thank you Ryan!

Ryan, when you work on the second part of this tutorial, add a belongs_to relationship to Survey. For example: author. In survey.rb add accepts_nested_attributes_for :author. Incorporate this into your form.

I mention this because nested forms doesn't handle belongs_to relationships properly. If you want to change the author for a single survey, it will do something like:

update authors set name = 'bar' where id = 1

Which affects all surveys that point to that author.

What it should do is:

insert into authors (id, name) values (2, 'bar')
update surveys set author_id = 2 where id = 5

Thank you very much for your work.
Is there a way to integrate accepts_nested_attributes_for and formtastic?

looing forward to see your part two

Thanks for the screencast, hoping part 2 will be has many through example of the nested forms.

this is one of my favorite and helpfull episodes.

anxiously watting the part 2.

I asked the same question Yinghai, someone claimed you could, but I've not yet see it work.

Ryan, I'm with Lyle. Is there any way you can get this on the opposite end of the relationship on the belongs_to? It should work is what I've seen on the internet but I keep getting errors.

Also, does it work with anything other than a has_many with belongs_to relationship?

_delete vs _destroy:

DEPRECATION WARNING: _delete is deprecated in nested attributes. Use _destroy instead.. (called from _delete at /usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/nested_attributes.rb:263)

Thanks!

StuFF mc, Ryan is using the Textmate "Ruby on Rails" bundle to create the partials. This is available with "control shift H" or from the bundle menu "Ruby on Rails > View Templates > Create partial from selection"

David, Ryan is using Textmate's column edit to quickly change the "builder." to "f." To use this push and hold the option button, your Textmate cursor changes to a cross, left click and drag the cross to select the column of text you want to change. Once you have a selection just type the new text you want.

Nice work Ryan - Thanks for picking up complex forms again.

Btw. is there a simple way to associate already created questions with a new survey?
Can a survey contain questions that are already part of other surveys?

Thanks
yanosz

@steve I had the same issue. I think Ryan's setup must have magic in it cause the api says to do it the way you did and not with :symbol.

Another great screencast and glad you're updating your Complex Forms series. That's been one of my favorites, but

@ryan, or anyone for that matter, do you think you'll ever address how to get the same model multiple times in the one form?

Great screen cast, just what I need right now!
I'm trying to understand the :reject_if => lambda { |a| a[:content].blank? }
I have forms with multiple inputs and checking for blank inputs wants all of them filled out. For example, if instead of "Question" as the input it had "First Name", "Middle Name" and "Last Name". How can you check that the first name is not blank but have it be optional whether to fill out the middle name? Which levels of the nesting attributes have to have no blanks to validate?

Thanks!

I love you and need part two immediately.

I didn't read all of the comments but I just ran into something on rails 2.3.2, when I use the

:reject_if => lambda{|a| a[:content].blank? }

it was rejecting everything, I needed to change it to

:reject_if => lambda{|a| a['content'].blank? }

Not sure if it was something silly I was doing or not but worth mentioning if it saves someone some time.

Looking forward to Parts 2 and 3!

Ryan - Another great episode!!! I greatly enjoy and appreciate your casts!

As always, thanks for the great cast.

I was wondering if there was a way to access the underlying model from within a form builder, to use data from the db to dynamically create things like the "labels" for the form.

So let's say you have the following form: http://pastie.org/780413

Is there some way that I can get data from the db for instance for the label. So that in stead of "Question", I can do something like question(:name) or question.name or question[name] or whatever it would be. I've tried a lot of different things.

I'd be using it in a different context, so that would explain why it may not make much sense in the current example.

I'd appreciate any help.

-A.

Wow, I was just about to start a project with nested forms and was looking around for sample code.

Great work.

Does anyone know how can we use this method with Paperclip plugin?
I mean, when we have Survey model and Photo model for example.
Every Survey has many Photos, i.e. Survey has multiple attachments.

Thanks in advance!

@Sergei

Look into polymorphic Paperclip attachments :)!

Thank you sooo much for this. Rescued me from a 3 hour head banging session

beautiful.

Sorry I can't get to everyone's question, but for those having trouble with the "a[:content.blank?" and "_destroy" behavior working, make sure you're using the latest version of Rails (2.3.5). This behavior has changed recently, and even some of the documentation is out of date.

Ryan - you are my savior -

needed a solution like this for some time now. But i still have a question

How can i build a survey with many questions and many answers but all user see the same questions and can have only one answer per question. Only the admin can see and edit multiple answers and questions. Your help is very much appreciated

What if I need in partial views/surveys/_answer_fields.html.erb access to some answer attribute, for example answer.id, just use there f.object.id ? Not very nice solution, anyone has better one ?

Thanks, DanS! I love it! I never even knew to try that! (Re: TextMate's column edit)

I'm implementing the Remove checkbox option. When the user checks the first of the nested records for removal and I perform a page.reload, the line is removed; however, the first checkbox of the remaining lines is checked. This only occurs in Firefox. It's fine in Safari and Chrome. Does anyone have any ideas on how to fix this problem?

can anybody help me. i always get
unknown attribute: _destroy when trying to delete a record.

Hi Ryan
    Thanks for this screencast. I am pointing out another general issue here. I am validating html at
http://validator.w3.org/check
   I just added validates_presence_of :name in survey model and without a name when i submit as usual i get the page with error list And when I validates its source I got some error That is exactly as

document type does not allow element "div" here; missing one of "object", "ins", "del", "map", "button" start-tag

    <div class="fieldWithErrors"><label for="survey_name">Name</label></div><b.....

  Why this happens?Is it any issue?

Thanks again
sijo

I can only get this to work with projects *created* using the latest version of Rails. The questions are never inserted into the database. It doesn't seem to matter that I have upgraded Rails. Does anyone know what I need to change in a project created with an older version to get this to work?

What if you always want to start with at least one question? Let's say a user submits a survey with no questions, but then wants to add a question when editing the survey?

I know this can be done via javascript (see part 2), but how would I do this without javascript?

I'm basically looking to get the edit view to populate with at least one question field even if that question doesn't exist, and when update_attributes is called to add the new question that was entered.

At the moment, I can do:

If @survey.questions.empty?
@survey.questions.build
end

In my edit method, but the update method is not saving the new question added when editing a survey.

Help!

Wow., Thank you very much

Thanks for the screencast Ryan :-). I also have validations set up, however, on error the child model errors are displayed first, instead of the parent's. Since the parent fields are the first to show up, those errors should be displayed first. any ideas on what I could be doing wrong? Thanks again.

Awesome! Thanks Ryan!

Very Good!
I am work in Windows + Rails 2.3.4,have some problems.
a. proc {|a| ..} replace lambda {|a|..}
b. <%= f.check_box :_delete %> replace <%= f.check_box :_destroy %>

this is an awesome tutorial. But when i try it out, i encounter some problem.

It simply won't save the questions and survey name to the database after i added field_for in my view. Anyone else having that issue?

If I remove it, survey name are saved

This is going to sound kind of dumb--I'm sure I just have a missing bracket or something--but when I follow along, I can't get anything at all to render after the fields_for call.
In the following example code, TEST 1 shows up, but TEST 2 and TEST 3 do not--and neither does the partial. The next thing is the submit button.
I would appreciate any help!
Here is my code:

  <p>
    <%= f.label :birthdate %><br />
    <%= f.date_select :birthdate %>
  </p>
  <p>
  TEST 1
    <% f.fields_for :roles do |builder| %>
    TEST 2
      <%= render "_role_fields", :f => builder %>
      TEST 3
    <% end %>
  </p>
  <p><%= f.submit 'Create Actor' %></p>
<% end %>

Okay, I figured it out, but it doesn't make any sense to me.

In my code, an actor has many roles, so I wrote <%= f.fields_for :roles do |builder| %> and that didn't work.

Changing it to <%= f.fields_for :role %> works. Maybe this is because at the beginning a New Actor has no roles? Is 0 singular?

It works, so I guess I don't care, but I'd sure like to know why, if anyone gets a minute. Thanks.

Yep. When I added the pre-building 3 roles to my New action, :roles worked. Sorry, I'm a newb! Thanks for the Railscasts, Ryan--they're a great tool.

Thank you, Nicolás Hock!

In Rails 2.3.4
builder.check_box :_destroy
should be
builder.check_box :_delete

This is a great screen-cast, but how do you display a nested attribute in the index view.

I keep getting nil?
error.

Hey Ryan, Thanks for the tutorial. It would be awesome if i can get it so work tho... Whenever i type questions for a new survey and hit 'submit' the questions never get to the database.. . I'm running rails 2.3.5 on windows xp64 and Ruby 1.8.7.

The surveys are getting through just not the questions.

Any ideas on why that might be?

Hi, was just going thru this tutorial. All is fine but when I try to render the nested forms for the questions or answers in the main form, I get an error saying unable to find template /surveys/_questions_form.rb

Logs dont tell much except it points to the line which is calling the render.

I am not sure of the resource.map and how it works but is there something else I need to do to render correctly?

I am running Rails 2.3.5

Does someone knows how to implement FCKeditor on a nested attribute?

Hey Ryan, great screencast! Didn't know it existed until just now :)

In the beginning of the screencast you say there isn't much documentation on creating the views, but there is in fact some in the fields_for docs: http://api.rubyonrails.org/classes/ActionView/Helpers/FormHelper.html#M001605

You might want to add that link to the list of links.

Cheers

Is this broken in Rails 3 for anyone?

Hay @Shai, I was following this tutorial in Rails 3 and it is broken indeed. I get a ActiveRecord::AssociationTypeMismatch with the message

User(#11741180) expected, got ActiveSupport::HashWithIndifferentAccess(#3929460)

Very dissapointing. I may be doing something wrong, but I have checked this from every possible angle and I guess it's Rails 3 fault. Actually, I removed the accepts_nested_attributes_for call from the model and submitted the form and I got exactly the same error.

Sorry, I posted my website url wrongly in the previous comment.

And to add something to the previous comment (and not being suspected as spammer) I may add that the only thing that's left for me to confirm this, is to test my code in Rails 2.3.x, but unfortunately the project I'm working on is already being mounted on Rails 3 and already absolutely dependant on it. I may extract the relevant parts and test it on Rails 2.3.x to see if it works.

I ran this episode's project both on rails 2.3.5 and rails 3.0.0.beta3 and it works great, so I guess it's me. I'm shocked :-O

newbie question: why ryan uses survey_id:integer and question_id:integer when generating models and not survey:references and question:references. what is the difference? thanks

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Ryan, excellent Railscast thank you.

How are you populating the form with sample questions simply using a keyboard shortcut?

I noticed a lot of people running into a problem where their nested records were not saving to the data base.

There seems to be an issue with what Rails version is being used. But if you are using 2.3.5 or higher your code should work just as Ryan says.

I made a stupid mistake that had me stumped for hours, so I thought I would make a note of it in case anyone else is having the same problem.

The mistake I made was a typo in the accepts_nested_attributes_for in my model. You should double check the symbol that you are checking if '.blank?' or not.

If you have a typo, then of course it will be 'blank?' and therefore will always be rejected and never saved.

Example below of typo:

accepts_nested_attributes_for :links,
:reject_if => lambda { |a| a[:typo].blank? },

:allow_destroy => true

I wish you would do a screencast about how to add multiple records of a single model with one form. I've done a ton of searching and can't seem to find a satisfactory answer that doesn't involve using a parent class.

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Suppose you have to assign a "correct" answer through a radio box beside each answer string.

For instance (_answer_fiels.html.erb):

<%= f_question.radio_button :answer_id, f.options[:child_index], :checked => false %>

<%= f.text_field :content %>

--
I can't get the id of the new answer ! Can anyone help me???

Thanks for another quality screencast! Your effort is always appreciated!

Your railscasts are great !

I still have a problem :
parent model, child model
How can I set automatically some values in child fields il
parent and child objects are new ?

@niber: same question.. I was trying f.options[:child_index]

Is there any way to define a callback method when for instance each answer is saved?

Thanks for share.

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I am near completion of a survey website in which I am making use of nested model forms.

HI,

I need to know if any nested attributes is blank then how it would work?
e.g -
In my case user have addresses & photos(nested attributes) but not mandatory while adding user if i haven't added photos & submit form then while editing that user it will not shown me photo upload field because photo object is not exist for that user

can you explain me how should it work?

Thanks for sharing your article. I really enjoyed it. I put a link to my site to here so other people can read it. My readers have about the same interets

I really appreciate something like this with MongoMapper?

There are certainly a lot of details like that to take into consideration. That is a great point to bring up. I offer the thoughts above as general inspiration but clearly there are questions like the one you bring up where the most important thing will be working in honest good faith

It looks nice and I am in need of this.