Mapping xml to active record objects

rubyonrails-talk
1

I’ve built a simple service that returns an xml feed like so:

blah blah 1 blah blah 2 etc..

What is a quick way to map this result to an array of user objects?

Thanks

Marlon

2

Just to answer my own question: Hpricot!

Very, very easy to do this now. Here’s an example.

doc = HJpricot(open(“http://locahost:3000/user/list”)) (doc/:user).each do |user| u = User.new u.id = (user/:login).innerHTML u.first_name = (user:/:first_name).innerHTML users.push(u) end

This has got to be the easiest thing I’ve ever done to consume XML.

3

Here's another option... If your xml elements match your User model's attribute names, you can just convert the xml to a hash and loop through its contents:

xml = <your xml> users = Hash.from_xml(xml)['users']['user'].each { |user_vals|   users << User.new(user_vals) }

b

Marlon Moyer wrote:

4

I've got an almost identical problem, except my data looks like:

<users>   <user id="1">     <first_name="blah"/>     <last_name="blah"/>   </user>   <user id="2">     <first_name="blah"/>     <last_name="blah"/>   </user> ... </users>

I'm really struggling with Hpricot - my brain just isn't working today (probably because of the aircon problems at work today...). If someone could show me how to map *this* to an array of User objects, I'd greatly appreciate it.

Thanks in advance

Dave M.

5

Sorry, I think the quick and easy stops once you start having attributes on your elements (or, have elements that don't match your user's fields).

Take a look at ReXML:

http://www.germane-software.com/software/rexml/docs/tutorial.html

Comes with standard with Ruby, IIRC.

b

David Mitchell wrote:

6

Yep, that's kind of what I suspected.

Thanks

Dave M.

7

Um, that's not even XML. But if it were XML (e.g. <first_name>blah</ first_name>) you could do something like this:

  # require 'rubygems' # if installed via Gems   require 'xml/libxml'   doc = XML::Document.file('users.xml')

  doc.find('//user').each do |user|     u = User.new     u.id = user.find_first('@id').content     u.first_name = user.find_first('first_name').content     u.last_name = user.find_first('last_name').content     users.push(u)   end

8

yep, that’s what I was thinking about the format, but given that feed, you could also do something ugly like this:

require ‘rubygems’ require ‘hpricot’

doc = Hpricot(’

' )

(doc/“user”).each do |user| puts “user id = #{user.attributes[‘id’]}” puts “first_name = #{user.children[0].to_s.scan(/first_name=”([^“]*)”/).to_s}"

end

9

actually, it is xml

the <tagname/> is shorthand for <tagname></tagname>