building xml

[MikeShank]

I'm having trouble trying to build up an xml file.

basically I'm looping thru an array and I want to append items to a node based on a value.

so if i have an array like:

 my_array = [["sam", "string 1"], ["sam", "string 2"], ["joe", "string 1"]] 

I want to end up with xml like:

<people>
<person ="sam">
<dialog>string 1</dialog>
<dialog>string 2</dialog>
</person>
<person ="joe">
<dialog>string 1</dialog>
</person>
</people>

Here's my attempt:

  people_listing_xml ="<people>\n"
  people_xml = Builder::XmlMarkup.new(:target => people_listing_xml, :indent => 1)
  
  //inside the loop
          people_xml.chat "person"=>person do
              people_xml.dialog dialog
          end
  
  people_listing_xml << "</people>\n" 

thanks for any help

[MikeShank]

I guess my question really is how do I append values to any existing node?

So, in my example if I wanted to add some more entries for "sam" I would need to select the person with the id of sam and add an entry.
I know this is probably simple stuff but I'm stumped

[Fenrir2]

I think this function is helpful:

people = [["sam", "a"], ["sam", "b"], ["joe", "c"]] 

def group(ary)
  res = {}
  for ele in ary
    res[ele[0]] = (res[ele[0]] || []) + [ele[1]]
  end and res
end

group(people) # => {"joe"=>["c"], "sam"=>["a", "b"]}

[MikeShank]

Hey Fenrir, thanks for that.
I'm not sure how it applies to my problem though.
Is it really as hard as I think it is to append to an xml node?

[Fenrir2]

Yes. I don't know how builder works exactly, but it seems to be nearly impossible to append to an existing node.

That's why I wrote that function ;-). If you look closely, you see that the function transforms the original array to a hash that's structured like your XML. You should insert a new loop *inside* people_xml.chat "person"=>person do ... end, and add a node for every element in the array of the hash.

Please tell me if this isn't clear.

[MikeShank]

Hi,
Yes, your method is clear. Just suprised you can not simply append to a node
Thanks

[Fenrir2]

Actually it's not strange at all, because builder doesn't create an object model of the xml, but it just creates a string. If you want to append to a node, use REXML, but in your case, this is an overkill.

Also:

 people_listing_xml ="<people>\n"
  people_xml = Builder::XmlMarkup.new(:target => people_listing_xml, :indent => 1)
  
  //inside the loop
          people_xml.chat "person"=>person do
              people_xml.dialog dialog
          end
  
  people_listing_xml << "</people>\n"

Can be written like:

x = Builder::XmlMarkup.new(:indent => 1)
x.people {
  //inside the loop
  x.chat(:person => person) {
    x.dialog dialog
  }
}

Which looks cleaner.

[Sigzag]

require 'builder'

my_array = [["sam", "string 1"], ["sam", "string 2"], ["joe", "string 1"]]
my_hash = my_array.inject(Hash.new { [] }) { |g,p| g[p[0]] <<= p[1]; g }
xml = Builder::XmlMarkup.new(:target => (my_output = ''), :indent => 1)
xml.people do
  my_hash.each do |name, dialogs|
    xml.person :name => name do
      dialogs.each do |dialog| xml.dialog dialog end
    end
  end
end

print my_output

Outputs this;

<people>
 <person name="joe">
  <dialog>string 1</dialog>
 </person>
 <person name="sam">
  <dialog>string 1</dialog>
  <dialog>string 2</dialog>
 </person>
</people>

Don't know if I really understood the problem, but at least it looks like what you wanted to end up with, so I hope it helped somewhat.
I suppose if you wanted to add a new node you could just:
my_array << ["sam", "some more"]
and generate the xml again.