尝试以红宝石形式使用下拉菜单

Question

First off, I'm pretty new to Ruby and Ruby on rails, so bear with me.

I'm attempting to have my categories section of my form utilize my category table in my db so that when the author wants to select on a category, they can just select the drop down menu and choose one. For now, I've hard coded them and this works

<%= form_for(@article) do |f| %>
  <% if @article.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@article.errors.count, "error") %> prohibited this article from being saved:</h2>


    <ul>
      <% @article.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :title %><br>
    <%= f.text_field :title %>
  </div>
  <div class="field">
    <%= f.label :content %><br>
    <%= f.text_area :content %>
  </div>
  <div class="field">
    <%= f.label :author_id %><br>
    <%= f.text_field :author_id %>
  </div>
  <div class="field">
    <%= f.label :category_id %><br>
    <%= f.select (:title), [['Finance'], ['Marketing'], ['Programming'], ['Leisure'], ['Management'], ['Food']] %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>

<% end %>

but, by switching the categories section to

<div class="field">
    <%= f.label :category_id %><br>
    <%= f.select :category_id, Category.all %>
  </div>

it will give me a drop down box containing each hash, and I'm not to sure why, but I can't do Category.all.name to get the names (I'm assuming it is because it's in a hash). Any help would be great appreciated.

Answer 1

Have you defined the Category model in your Controller? The form can/will only know what the controller knows. It cannot know any more. If this form is attached to the articles_controller then it will have access to @article, but it won't have access to @category.

So this leaves you with a couple options. Define category somewhere in your controller, OR alternatively (and this would be my suggestion) setup some type of association for your Articles model.

Does Article have many Categories? This is a great opportunity to setup that has_many association, and then you can access the category model via Article's associations methods.

This is my suspicion, but we really don't have enough information here. Can you post your controller, and your article model so we can see everything that is going on? Also, what error do you get specifically?

Answer 2

It looks like that you need to change you select use options_for_select tag:

<%= f.select :category_id, options_for_select(Category.all.collect {|c| [ c.name, c.id ] }), :include_blank => true %>

if you want to pre-populate category_id

<%= f.select :category_id, options_for_select(Category.all.collect {|c| [ c.name, c.id ]}, @article.category_id), :include_blank => true %>

For more information options_for_select