Rails - Mar 2006 - Newbie question: How to represent parent-child denormalization

I am building a relatively trivial application to try to learn my way
around Rails.  I am having difficulty understanding how to navigate a
heavily denormalized hierarchy.  Could someone direct me to a bare-bones
explanation of using rails to navigate database hierarchies?

I am an experienced developer.  Most of my work has been desktop client
server, high performance, or server to server interprocess work in large
scale systems (8K plus users).

However, I am new to Ruby and the rails environment.  Furthermore, I
have never been comfortable with html development.  My idea of a perfect
screen is plain white that is sparsely populated with black text with a
single font and no effects.  The default stylesheets that rails
generates are quite a bit more elaborate than I would choose to
build :o)

I am trying to build a flash-card application that contains quizzes,
questions, possible answers, and presentations, plus historical records
of users''s answers over time (quiz_instances, question_instances,
response_instances).

I have been working from Thomas and Hansson (Agile Web Development With
Rails), but I appear to be missing something in the move from the famous
"depot" example into real life.  I cannot for the life of me figure
out
how to navigate from parent objects (such as a quiz) to child objects.
I find a lot of what I generally consider "fluff" - adding pictures
and
fonts, and tweaking positions on the screen, but I am not finding how to
build controls to navigate a hierarchy.

I could either be having issues with some web development fundamental,
or my own misunderstanding of how Rails is supposed to work.

What I have now is a skeleton that allows me to create, edit, and
destroy quizzes.

I have created the question controller, model, and views.  However, I
can''t seem to be able to redirect to the list of questions from the
quiz
controller.  I think I understand how to nest lists once I understand
how to navigate a hierarchy.

Since questions have no content of their own, I will also need to
navigate to the presentation level to get the actual text for the
question.  This is a simple hierarchical structure, with the only twist
being that a presentation (text, audio, and graphic) may be owned by
either a quiz (preamble and postamble), a question (preamble, body,
postamble), or a possible answer (body).

This chart may make it more clear (or not):

(quiz) 1..n (question) 1..n (possible answer) 1..n (presentation)
            (question.preamble) 1..1 (presentation)
            (question.body) 1..1 (presentation)
            (question.postamble) 1..1 (presentation)
(quiz.preamble) 1..1 (presentation)
(quiz.postamble) 1..1 (presentation)

At present, I have defined quiz and question.  I believe that once I
have these under control I will be able to move forward.

Thanks in advance.
David Johnson

Hi David, you may want to look into the acts_as_tree structure

On 3/8/06, David Johnson <johnson_d@cox.net>
wrote:
>
> I am building a relatively trivial application to try to learn my way
> around Rails.  I am having difficulty understanding how to navigate a
> heavily denormalized hierarchy.  Could someone direct me to a bare-bones
> explanation of using rails to navigate database hierarchies?
>
> I am an experienced developer.  Most of my work has been desktop client
> server, high performance, or server to server interprocess work in large
> scale systems (8K plus users).
>
> However, I am new to Ruby and the rails environment.  Furthermore, I
> have never been comfortable with html development.  My idea of a perfect
> screen is plain white that is sparsely populated with black text with a
> single font and no effects.  The default stylesheets that rails
> generates are quite a bit more elaborate than I would choose to
> build :o)
>
> I am trying to build a flash-card application that contains quizzes,
> questions, possible answers, and presentations, plus historical records
> of users''s answers over time (quiz_instances, question_instances,
> response_instances).
>
> I have been working from Thomas and Hansson (Agile Web Development With
> Rails), but I appear to be missing something in the move from the famous
> "depot" example into real life.  I cannot for the life of me
figure out
> how to navigate from parent objects (such as a quiz) to child objects.
> I find a lot of what I generally consider "fluff" - adding
pictures and
> fonts, and tweaking positions on the screen, but I am not finding how to
> build controls to navigate a hierarchy.
>
> I could either be having issues with some web development fundamental,
> or my own misunderstanding of how Rails is supposed to work.
>
> What I have now is a skeleton that allows me to create, edit, and
> destroy quizzes.
>
> I have created the question controller, model, and views.  However, I
> can''t seem to be able to redirect to the list of questions from
the quiz
> controller.  I think I understand how to nest lists once I understand
> how to navigate a hierarchy.
>
> Since questions have no content of their own, I will also need to
> navigate to the presentation level to get the actual text for the
> question.  This is a simple hierarchical structure, with the only twist
> being that a presentation (text, audio, and graphic) may be owned by
> either a quiz (preamble and postamble), a question (preamble, body,
> postamble), or a possible answer (body).
>
> This chart may make it more clear (or not):
>
> (quiz) 1..n (question) 1..n (possible answer) 1..n (presentation)
>             (question.preamble) 1..1 (presentation)
>             (question.body) 1..1 (presentation)
>             (question.postamble) 1..1 (presentation)
> (quiz.preamble) 1..1 (presentation)
> (quiz.postamble) 1..1 (presentation)
>
> At present, I have defined quiz and question.  I believe that once I
> have these under control I will be able to move forward.
>
> Thanks in advance.
> David Johnson
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>


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I am Mark Daggett and I approve this message.
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I will try that as soon as I can.

Thanks!

On Thu, 2006-03-09 at 09:31 -0800, M Daggett wrote:
> Hi David, you may want to look into the acts_as_tree structure 
>