# Array to\_xml **URL:** \ **Category:** Rails\ **Created:** [October 7, 2008, 3:31am UTC](https://www.ruby-forum.com/t/array-to-xml/150299 "2008-10-07T03:31:00Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/5f9b8f/32.png) [@sam](https://www.ruby-forum.com/u/sam)\ **Post date:** [October 7, 2008, 3:31am UTC](https://www.ruby-forum.com/t/array-to-xml/150299/1 "2008-10-07T03:31:00Z")
Why is it that… {code} > > myarray = [“one”] > > =\> [“one”] > > > myarray.to\_xml > > RuntimeError: Not all elements respond to to\_xml > > from /foo/vendor/rails/activerecord/lib/…/…/activesupport/lib/ > > active\_support/core\_ext/array/conversions.rb:62:in `to\_xml’ > > from (irb):94 > > > {code} … however … {code} > > myarray2 = [{:one =\> “onevalue”}] > > =\> [{:one=\>“onevalue”}] > > > myarray2.to\_xml > > =\> "\\n\ **Author:** ![sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/5f9b8f/32.png) [@sam](https://www.ruby-forum.com/u/sam)\ **Post date:** [October 7, 2008, 3:58am UTC](https://www.ruby-forum.com/t/array-to-xml/150299/2 "2008-10-07T03:58:33Z") What do you want the resulting XML to look like? Usually XML has name/ value format. You can do this: class Symbol def to\_xml {self =\> self.to\_s}.to\_xml end end and then you can call :hello.to\_xml =\> hello That’s a little dangerous, though, and it may turn out that you should rethink the XML schema, and use hashes in general. ---
**Author:** ![sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/5f9b8f/32.png) [@sam](https://www.ruby-forum.com/u/sam)\ **Post date:** [October 7, 2008, 4:16am UTC](https://www.ruby-forum.com/t/array-to-xml/150299/3 "2008-10-07T04:16:41Z")
On 7 Oct 2008, at 02:30, Sam wrote: > from (irb):94 > “\>\n \n onevalue\n \n\n” > > > > In a nutshell, strings don’t have a to\_xml method, but hashes do. > {code} > > Is there a way I can convert an array to xml without having to wrap > each element in a hash??? What do you want the output to look like ? Fred ---
**Author:** ![sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/5f9b8f/32.png) [@sam](https://www.ruby-forum.com/u/sam)\ **Post date:** [October 7, 2008, 7:31am UTC](https://www.ruby-forum.com/t/array-to-xml/150299/4 "2008-10-07T07:31:33Z")
The standard thing to do is put classes in there instead of strings, so each error would be an instance of class Error, which would respond to to\_xml with foo or whatever. See, for example, Pat Maddox’s Blog: > **[eli.st](http://evang.eli.st/blog/2007/2/22/my-rails-gotcha-custom-to_xml-in-a-hash-or-array)** > > This domain may be for sale! If you are worried about reversibility, you can change active\_support \core\_ext\array\conversions so that the to\_xml method looks like this at the top: ``` options[:root] ||= all? { |e| e.is_a?(first.class) && ``` first.class.to\_s != “Hash” } ? first.class.to\_s.underscore.pluralize : “records” map!{|e| (e.class.name == “String”) ? {options[:root].to\_sym =\> e} : e} ``` raise "Not all elements respond to to_xml" unless all? { |e| ``` e.respond\_to? :to\_xml } ``` options[:children] ||= options[:root].singularize options[:indent] ||= 2 options[:builder] ||= Builder::XmlMarkup.new(:indent => ``` options[:indent]) The XML you get back isn’t pretty, but it doesn’t crash: \ foo bar Cleaning it up more than this might be a bit tricky. If this is something a lot of people would like, I’d look at it some more, but I think it’s pretty unusual, and it’s usually easier to use objects. -Michael ---
**Author:** ![sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/5f9b8f/32.png) [@sam](https://www.ruby-forum.com/u/sam)\ **Post date:** [October 7, 2008, 4:55am UTC](https://www.ruby-forum.com/t/array-to-xml/150299/5 "2008-10-07T04:55:16Z")
I’m wanting something like… foo bar I find it really interesting that a Rails controller will accept xml like… `one``two` … and transform it into a hash… { :process\_codes =\> { :code =\> [“one”, “two”] } } … but will not go back the other way when I want to convey errors… { :errors =\> { :error =\> [“foo”, “bar”] } } ---
**Author:** ![sam](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/5f9b8f/32.png) [@sam](https://www.ruby-forum.com/u/sam)\ **Post date:** [October 7, 2008, 7:55am UTC](https://www.ruby-forum.com/t/array-to-xml/150299/6 "2008-10-07T07:55:35Z")
Thanks Michael. I’ve taken the easy (and hacky) way out by using an ActiveRecord::Errors object which is transformed implements to\_xml quite nicely. The hacky bit is that I’m not always adding an error that coincides with an attribute of the model I’m exploiting … eg, errors.add( :code, “#{code} is not found” ) …when my model object doesn’t actually have a “code” attribute. Also… under some scenarios I may not have a model instance at all but need to create one in order to gain access to the to\_xml friendly Errors object by doing something like… errors = Player.new.errors … which is of course hacky, but more readily thrown together than implementing a custom errors class or modifying the conversions.rb The Errors object is also nice because it allows multiple errors with the same key… errors.add( :code, “#{code} is not found” ) errors.add( :code, “#{code} has already been processed” )