generating XML in rails

Question

I created a controller having an action:

def gen_books_xml
  @books = Book.find(:all, :conditions => {:owner_id => 1})
  respond_to do |format|
    format.xml { render :xml => @books.to_xml(:root => "Books", :skip_types=>true) }
  end
end

How could I implement the to_xml method in the Book model sa that it can generate the following format?

<?xml version="1.0" encoding="UTF-8"?>
<Books>
  <Owner>1</Owner>
  <Book><title>some title</title></Book>
  <Book><title>some title</title></Book>
  <Book><title>some title</title></Book>
  ...
</Books>

where there is only 1 Owner element and many Book elements

I can only output the Book elements but cannot output the one Owner in the same level of Books. Please HELP!!!

Answer 1

not solution, but hack

@books.to_xml(...).sub("<Books>","<Books><Owner>1</Owner>")

Answer 2

You should build it with Rails XML Builder, but be careful with the naming convention. PS, the examples are not tested, there might be some errors, use at your own judgement. Change your controller like so:

def gen_books_xml
  @owner_id = 1
  @books = Book.find(:all, :conditions => {:owner_id => @owner_id})
  respond_to do |format|
    format.xml
  end
end

Now, you have @owner_id and @books accessible from your views. Then create the builder file in views/controller_name/gen_books_xml.xml.builder:

xml.instruct!              # for the <?xml version="1.0" encoding="UTF-8"?> line
xml.books do               # xml.foo creates foo element
  xml.owner @owner_id      # you're inside a block so xml.bar will create <foo><bar/></foo> elements
  @books.each do |book|
    xml.book do
      xml.title book.title
    end
  end
end

You can modify this builder to make the XML look however you like.