Sinatra and Datamapper - inserting data to a one to many relationship table - ruby

Question

I have the following. Each article has a title and a body and also up to three urls. I would want to store the urls in a different table. Therefore in my form, i've a field for the urls. However they are not working, only the article fields get entered into the database. how should i specify them? Could any kind soul help me out with this?
class Article
include DataMapper::Resource
property :id, Serial
property :title, String
property :body, Text
has n, :urls, through => Resource
end
class Url
include DataMapper::Resource
property :id, Serial
property :url_01, String
property :url_02, String
property :url_03, String
belongs_to :article
end
post '/create' do
#article = Article.new(params[:article])
if #article.save
redirect "/articles"
else
redirect "/articles/new"
end
end
--------------------------------------
<form action="/create" method="post">
<p>
<label>Article Title</label>
<input type="text" name="article[title]">
</p>
<p>
<label>Article Body</label>
<input type="text" name="article[body]">
</p>
<p>
<label>Url</label>
<input type="text" name="article[url_01]">
</p>
<p>
<input type="submit">
</p>

Answer 1

I believe that
, through => Resource
is only needed if you are doing a many-to-many relationship. A one-to-many, which I think is what you want, does not require that. Check out the post and comment relationship shown on the associations page.
EDIT for comment:
If I were you, I would name my form fields normally and construct the database object manually, for example:
<form action="/create" method="post">
<p>
<label>Article Title</label>
<input type="text" name="title">
</p>
<p>
<label>Article Body</label>
<input type="text" name="body">
</p>
<p>
<label>Url</label>
<input type="text" name="url">
</p>
<p>
<input type="submit">
</p>
and then:
post '/create' do
#article = Article.new(
:title => params[:title],
:body => params[:body]
)
#url = url.new(
url_01 => params[:url]
)
#article.url = #url
if #article.save
redirect "/articles"
else
redirect "/articles/new"
end
end