如何让 Rails select() 工作？

Question

I'm running Rails 2.3.5 on a hosted server, and cannot upgrade to 3.

I have one database, and it has a list of cartoons with id , date , and title . I can navigate through them using text links, and I also want to be able to navigate using a dropdown select , but I can't get the select tag working. This isn't a form to create a new element. Whereas the form shows up (being empty), the select tag does not show up, not even an empty select tag.

Here's what I have:

*comics_controller.rb*

class ComicsController < ApplicationController
  before_filter :get_all_comics

  def get_all_comics
    @comics=Comic.find(:all, :order => "date DESC")
  end

  def view
    if params[:id].nil?
    @comic=@comics.first
    @prev=@comics[1]
    else
        @comic=Comic.find(params[:id])
        @prev=Comic.find(:first, :conditions => ["date < ?", @comic.date],
                             :order => "date DESC")
        @next=Comic.find(:first, :conditions => ["date > ?", @comic.date],
                                 :order => "date ASC")
    end
  end

end

comics/view.html.erb

<% form_for :comics, :url => { :action => "view" } do |f|
    f.select(:id,Comic.all,:prompt => true)
end %>
<img src="directory/<%= @comic.filename %>" />
<p class="title"><%= @comic.title %></p>
<p class="date"><%= @comic.date %></p>
<% unless @prev.nil? %>
    <a href="<%= @prev.id %>">Previous</a>
<% end
   unless @next.nil? %>
    <a href="<%= @next.id %>">Next</a>
<% end %>

Answer 1

The basic problem here is that the block tags you are using.

Rails uses two types of template tags: the <%= ones are used for anything which should be evaluated and returned to the client, whereas the <% would be used for control statements which do not return anything to the client.

Note also that anything in Rails 2 which is output with <%= is not safely escaped, and you should probably be using <%= h @comic.title %> (h for html escaping). However, if you use the plain <%= syntax in Rails 3, it will handle the escaping for you.

You would probably do better to move to Rails 3 if you are learning the framework from scratch.

Answer 2

<% form_for ... do |f| %>
<%= f.select(...) %>
<% end %>

Edit: I suggest you also add <%= submit_tag %> somewhere

Answer 3

I think the collection you are using needs a bit of formatting

f.select :id, Comic.all, :prompt => true

try

f.select :id, Comic.all.map { |c| [c.title, c.id] }, :prompt => true

# collection should resemble this format
[
  ["Batman", 1],
  ["Superman", 2],
  ...
]