Rails, AJAX, has_many, and me

[Tawnos]

If the topic didn't scare you away, thanks .

As part of a web app I'm writing, I'm creating a multiple choice test creation app.

The database is set up as such:

create table questions (
    id                  int             not null auto_increment,
    question            varchar(250)    not null,
    answer              varchar(100)    not null,
    wrong_answers_count int             default 0,
    primary key (id)
);

create table wrong_answers (
    id                  int             not null auto_increment,
    question_id         int             not null,
    answer              varchar(100)    not null,
    constraint fk_question foreign key (question_id) references questions(id),
    primary key (id)
);

The model for questions (question.rb) is like so:

class Question < ActiveRecord::Base
  has_and_belongs_to_many :tests
  has_many :wrong_answers, 
            :exclusively_dependent => true
  
  validates_presence_of :question, :answer
  
end

A Question must have at least one valid answer, which is the answer field from above.

The wrong answer (wrong_answer.rb) model:

class WrongAnswer < ActiveRecord::Base

  belongs_to :question, :counter_cache => true
  validates_presence_of :answer
  
end

I'd like the question creation to function so that there's two text input boxes, question and answer. They define the parent object's question and answer. Below those boxes is another, that allows the administrator to add a wrong answer. Adding the answer should be handled in memory, with no database update (as there is no question created until the answer is committed). Upon being added, the answer should appear in a text list above the edit box, with an "edit" and "delete" option. "Edit" turns the text into an edit box, allowing one to change the answer or delete it. "Delete" removes it from the in-memory database, or the real database if this is a question that has been opened for editing.

To this end, I have the following:
new.rhtml

<h1>New question</h1>

<%= start_form_tag :action => 'create' %>
  <%= render :partial => 'form' %>
  
<br />Wrong Answers:<br />
<div id="wrong_answer_list">
</div>

   <%= render(:partial => 'wrong_answer_editbox')  %>
  <br />
  <%= submit_tag "Create" %>
  
<%= end_form_tag %>

<%= link_to 'Back', :action => 'list' %>

_wrong_answer_editbox.rhtml

<!-- BEGIN _wrong_answer_editbox.rhtml -->
<%= form_remote_tag(:url => { :action => "add_wrong_answer" },
                    :position => :top) %>
                    
<%= text_field_tag('wrong_answer', '', :id => 'wrong_answer_body')  %>

<%= link_to_remote("Add",
                   :update => "wrong_answer_list",
                   :url => { :action => "add_wrong_answer" }) %>
                   
<%= end_form_tag %>

<!-- END _wrong_answer_editbox.rhtml -->

The text partial is similar to the edit box. The problem i'm having is this: how do I make the controller create an in memory WrongAnswer, associated with the uncreated question. Moreover, how do I transfer the lsit from memory to database?

I know this may be unclear. I'm sorry, please ask any needed questions for clarification and I'll do my best.

 

[doh]

I can't help you. I'm going to ask you a question though...

What are some good Ruby and Rails tutorials and involve projects from scratch that explain the "why" of why things are done? I'm also looking to buy some dead tree books, can you suggest any?

 

[Tawnos]

As you've probably seen elsewhere... Agile Web Development With Ruby on Rails. The first third is the "how". The next 2/3 is the "why".

Not perfect, but pretty damn close.

 

[doh]

As you've probably seen elsewhere... Agile Web Development With Ruby on Rails. The first third is the "how". The next 2/3 is the "why".

Not perfect, but pretty damn close.

That's what I had in mind. I can get that one and the updated Pragmatic Programmer for £37 delivered. Nice.