Rails - Jan 2006 - Creating multiple child objects from the same form

I''ve been digging into rails, but this one question has been a two day 
stumper. I''ve got a question/answer model that I''m trying to
work out.
Each question has multiple answers (they''re more like choices, it 
doesn''t matter whether they''re right or wrong), and
I''d like to have the
question creation form also have multiple fields in which to put the 
answer choices.  But with my code, I can only do one successful child 
creation.  The log only shows that one answer is being passed in.

Here''s the code as of right now:

############ models
class Answer < ActiveRecord::Base
  belongs_to :question
  validates_presence_of :answer, :question_id
end

class Question < ActiveRecord::Base
  validates_presence_of :question
  has_many :answers
end

############ question controller
  def create
    @question = Question.new(params[:question])

    if @question.save
      logger.debug(@question.inspect)
      params[:question_answer].each_value do |answer|
        @question.answers << Answer.new(:answer => answer)
      end

      flash[:notice] = ''Question was successfully created.''
      redirect_to :action => ''list''
    else
      render :action => ''new''
    end
  end

############# question''s _form
<%= error_messages_for ''question'' %>

<!--[form:question]-->
<p><label
for="question_question">Question</label><br/>
<%= text_area ''question'', ''question'',
{:cols=>"80", :rows=>"5"}  %></p>

<p><label
for="question_answer">Answer</label><br/>
<%= text_area "question_answer", ''answer[]'',
{:cols=>"80", :rows=>"5"}
%></p>

<p><label
for="question_answer">Answer</label><br/>
<%= text_area "question_answer", ''answer[]'',
{:cols=>"80", :rows=>"5"}
%></p>

<!--[eoform:question]-->

-- 
Posted via http://www.ruby-forum.com/.

The reason you''re only getting one answer field back on the post is
because
the names of the text areas are the same.  Change the second one to
name="question_answer_2" and you will see it in the params array.

--
Andrew Stone
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Andrew Stone wrote:
> The reason you''re only getting one answer field back on the post
is
> because
> the names of the text areas are the same.  Change the second one to
> name="question_answer_2" and you will see it in the params array.
Thanks for the tip, I''ve tried what you just offered and it still only 
put in the first answer, the second answer was not input.

################ New _form.rhtml

<%= error_messages_for ''question'' %>

<!--[form:question]-->
<p><label
for="question_question">Question</label><br/>
<%= text_area ''question'', ''question'',
{:cols=>"80", :rows=>"5"}  %></p>

<p><label
for="question_answer">Answer</label><br/>
<%= text_area "question_answer", ''answer[]'',
{:cols=>"80", :rows=>"5"}
%></p>

<p><label
for="question_answer">Answer</label><br/>
<%= text_area "question_answer_2", ''answer[]'',
{:cols=>"80", :rows=>"5"}
%></p>

<!--[eoform:question]-->

-- 
Posted via http://www.ruby-forum.com/.

You''re not going to be able to get the multiple values with:

params[:question_answer].each_value do |answer|

you''re going to need to explicitly get each question_answer:

e.g.
a1 = params[:question_answer_1]
a2 = params[:question_answer_2]


--
Andrew Stone
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Andrew Stone wrote:
> You''re not going to be able to get the multiple values with:
> 
> params[:question_answer].each_value do |answer|
> 
> you''re going to need to explicitly get each question_answer:
> 
> e.g.
> a1 = params[:question_answer_1]
> a2 = params[:question_answer_2]
Isn''t there a better way?  Because there will be an arbitrary number of
answers, so hard coding that in would not work.  There isn''t anyway to 
pass all the values into a hash from the form?

-- 
Posted via http://www.ruby-forum.com/.

you could do something like:

@params.each{|key,value|
  if key.downcase =~ /^question_answer/
    @question.answers << Answer.new(:answer => value)
  end
}


--
Andrew Stone
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If you name each field "question_answer[]", the value
params[:question_answer] will be an array of the values entered.

You should probably add the HTML option :name =>
"question_answer[]"
to each tag.  Let me know how that works for you.

Andrew''s solution of using regexes to parse all the params is also
workable, but I think storing them all into an array to begin with is
a little more elegant.

-Will

On 1/17/06, Xavier Lange <cuxrl@eiu.edu> wrote:
> Andrew Stone wrote:
> > You''re not going to be able to get the multiple values with:
> >
> > params[:question_answer].each_value do |answer|
> >
> > you''re going to need to explicitly get each question_answer:
> >
> > e.g.
> > a1 = params[:question_answer_1]
> > a2 = params[:question_answer_2]
>
> Isn''t there a better way?  Because there will be an arbitrary
number of
> answers, so hard coding that in would not work.  There isn''t
anyway to
> pass all the values into a hash from the form?
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

Thanks Will, I did not know that. :)

--
Andrew Stone
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Andrew Stone wrote:
> you could do something like:
> 
> @params.each{|key,value|
>   if key.downcase =~ /^question_answer/
>     @question.answers << Answer.new(:answer => value)
>   end
> }
Wow, that''s a slick way of doing it!

Now it inserts all the values at the same time, only catch is that it 
includes the data type.  How can I tell what else is inside of the 
''value'' object?

 --- !ruby/hash:HashWithIndifferentAccess answer: W

-- 
Posted via http://www.ruby-forum.com/.

I used the regex in the past for my pages.  For instance, I may have
checkboxes for departments on a company division edit page.  I would append
the department_id to the name of the check box (department_1), then flip
through with the regex, split the key to get the id and add departments to
the division.

By using the array as you pointed out, I would have to query to find the
department by the name or description (or whatever) that was shown to the
user.

Or, am I missing something completely obvious.

--
Andrew Stone
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You could also do fields with names:

question_answer[answer1], question_answer[answer2], etc...

This makes params[:question_answer] a hash w/ "answer1" as the key and
the value in the "answer1" field as the value, "answer2" as
the key
and the value in "answer2" as the field value...  does that help at
all?

-Will

On 1/17/06, Andrew Stone <stonelists@gmail.com>
wrote:
> I used the regex in the past for my pages.  For instance, I may have
> checkboxes for departments on a company division edit page.  I would append
> the department_id to the name of the check box (department_1), then flip
> through with the regex, split the key to get the id and add departments to
> the division.
>
>  By using the array as you pointed out, I would have to query to find the
> department by the name or description (or whatever) that was shown to the
> user.
>
>  Or, am I missing something completely obvious.
>
> --
> Andrew Stone
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
>
>

Andrew Stone wrote:
> I used the regex in the past for my pages.  For instance, I may have
> checkboxes for departments on a company division edit page.  I would 
> append
> the department_id to the name of the check box (department_1), then flip
> through with the regex, split the key to get the id and add departments 
> to
> the division.
> 
> By using the array as you pointed out, I would have to query to find the
> department by the name or description (or whatever) that was shown to 
> the
> user.
> 
> Or, am I missing something completely obvious.
I had the idea that you could pass in values using a [] at the end of 
the variable name and it would then let you treat the variable as a 
hash.  Guess not.  Which is a shame, because that could be very handy!

-- 
Posted via http://www.ruby-forum.com/.

Yeah, that makes sense.  Not that I was having trouble with the regex, but I
always like to find cleaner implementations.  Especially since, compared to
JAVA, I''m really new to Ruby.

thanks again... :)
--
Andrew Stone
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Will Briggs wrote:
> You could also do fields with names:
> 
> question_answer[answer1], question_answer[answer2], etc...
> 
> This makes params[:question_answer] a hash w/ "answer1" as the
key and
> the value in the "answer1" field as the value,
"answer2" as the key
> and the value in "answer2" as the field value...  does that help
at
> all?
> 
> -Will
Yea, I had tried that and rails spit out that it wasn''t allowed as an 
instance name.  This is what I just tried now: <%= text_area 
"question_answer[1]", ''answer'',
{:cols=>"80", :rows=>"5"} %> and rails
said "`@question_answer[1]'' is not allowed as an instance variable
name".

-- 
Posted via http://www.ruby-forum.com/.

Any ideas on how to deal with "--- !ruby/hash:HashWithIndifferentAccess 
answer: WHAT" being inserted instead of just "WHAT"?

I tried @question.answers << Answer.new(:answer => value[answer]) which
threw an error about being the incorrect method. Then I tried 
"@question.answers << Answer.new(:answer => value.type)" so
it would put
into the table what kind of object it was, but then ruby said that it 
couldn''t dump anonymous class Class.

What''s a good way to see what the variables are and what they contain?


################### what''s in the controller
      @params.each{|key,value|
        if key.downcase =~ /^question_answer/
          @question.answers << Answer.new(:answer => value)
        end
      }

-- 
Posted via http://www.ruby-forum.com/.

Ok try doing this:

<%= text_area "1", ''answer'', :prefix =>
''question_answer'', {:cols =>
"80", :rows => "5"} %>

-Will

On 1/17/06, Xavier Lange <cuxrl@eiu.edu> wrote:
> Will Briggs wrote:
> > You could also do fields with names:
> >
> > question_answer[answer1], question_answer[answer2], etc...
> >
> > This makes params[:question_answer] a hash w/ "answer1" as
the key and
> > the value in the "answer1" field as the value,
"answer2" as the key
> > and the value in "answer2" as the field value...  does that
help at
> > all?
> >
> > -Will
>
> Yea, I had tried that and rails spit out that it wasn''t allowed as
an
> instance name.  This is what I just tried now: <%= text_area
> "question_answer[1]", ''answer'',
{:cols=>"80", :rows=>"5"} %> and rails
> said "`@question_answer[1]'' is not allowed as an instance
variable
> name".
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

The value is from |key,value| is just going to be a string.

You can use

value.inspect
value.class
or just: value
in a log statement to see different attributes of the object.  of course,
inspect varies on the output depending on what type of object it is.

--
Andrew Stone
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Andrew Stone wrote:
> The value is from |key,value| is just going to be a string.
> 
> You can use
> 
> value.inspect
> value.class
> or just: value
> in a log statement to see different attributes of the object.  of 
> course,
> inspect varies on the output depending on what type of object it is.
Ah, so type wasn''t working but inspect does the trick!  Then I figured 
out that it needed the string "answer" as the key.  So with 
Answer.new(:answer => value["answer"]) my little question/answer
system
is in good shape!

-- 
Posted via http://www.ruby-forum.com/.

Sorry to barge into your thread :)

However one thing about this approach is that supposing one of your 
answers fail validation, you will only get a rather cryptic error 
message like "Answer is invalid", with no other explanatory text or
any
text fields highlighted (using the default scaffolds that is).

This will happen even if you did provide the appropriate error messages 
in your Answers class! Is there any way to sort of "bubble" the error 
messages from the child object up to the main form?

Thanks.

-- 
Posted via http://www.ruby-forum.com/.

Woei Shyang wrote:
> Sorry to barge into your thread :)
> 
> However one thing about this approach is that supposing one of your 
> answers fail validation, you will only get a rather cryptic error 
> message like "Answer is invalid", with no other explanatory text
or any
> text fields highlighted (using the default scaffolds that is).
> 
> This will happen even if you did provide the appropriate error messages 
> in your Answers class! Is there any way to sort of "bubble" the
error
> messages from the child object up to the main form?
> 
> Thanks.
This solution isn''t as elegant as I at first thought.  I''m
trying to get
the edit method to work, and it seems like it''s repeating what I did
for
the create method.  And I thought ruby was all about DRY :)

The model is pretty simple, but I don''t know how it will react when it 
fails validation.  There has to be a better way, right?

-- 
Posted via http://www.ruby-forum.com/.

Xavier Lange wrote:
> This solution isn''t as elegant as I at first thought. 
I''m trying to get
> the edit method to work, and it seems like it''s repeating what I
did for
> the create method.  And I thought ruby was all about DRY :)
> 
> The model is pretty simple, but I don''t know how it will react
when it
> fails validation.  There has to be a better way, right?

I hope there is a better way. :/

Surely there is someway to hack the _form partial into doing something 
useful for objects that has_many instances of a child subclass... right?

*crickets chirp*

-- 
Posted via http://www.ruby-forum.com/.

Woei Shyang wrote:
> I hope there is a better way. :/
> 
> Surely there is someway to hack the _form partial into doing something 
> useful for objects that has_many instances of a child subclass... right?
> 
> *crickets chirp*
Hey RoR people, we''re talking to you!  Haha.

Well, I think I''ll make the rest of this application and come back to 
this later.  Maybe I''ll have learned a bit more so it doesn''t
feel quite
as hacked together.  Thanks for the help everyone!

-- 
Posted via http://www.ruby-forum.com/.

Xavier Lange wrote:
> Hey RoR people, we''re talking to you!  Haha.
> 
> Well, I think I''ll make the rest of this application and come back
to
> this later.  Maybe I''ll have learned a bit more so it
doesn''t feel quite
> as hacked together.  Thanks for the help everyone!
A thought did pop into my head just now.. maybe we can shift the 
validation code into the controller, but it does seem like quite a waste 
considering the child class has its own validation as well.

Just a suggestion though :)

-- 
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