Ironruby core - Jan 2009 - Xml Processing in IronRuby - Help me improve the wrapper

Hello,

I''ve just been playing around with IronRuby and processing some XML
from a REST service.  I''ve created this wrapper:
require ''mscorlib''
require ''System, Version=2.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089''
include System
require ''System.Xml, Version=2.0.0.0, Culture=neutral,
PublicKeyToken=b77a5c561934e089''
include System::Xml

#Wrapper around .Net XMLDocument to make it easier to query with -
more like REXML
class Document
  def initialize(xml)
    @document = XmlDocument.new
    @document.load_xml xml
  end

  def get(xpath)   #.collect - I want to pass the block in, not have
to use it on the outside.
    @document.SelectNodes(xpath)
  end
end

class XmlNodeList
  def get(name)
    list.select {|e| e.Name == name}
  end
end

class XmlElement
  def get(name)
      if has_attribute name
        get_attribute name
      else
        get_elements_by_tag_name name
      end
  end

  def text
     inner_text
  end
end

My first problem is that I''m getting XmlElement object instead of
XmlNode from an XmlNodeList.  If I had XmlNode, then I could do
e[''n''].text - which is what I want.  As a result, my code to
access
the N element looks like this:

require ''xml''
@document =
Document.new(''<x><x1><n>test</n><z>aaa</z></x1></x>'')
@document.get(''x'').collect {|n| puts
n.text}
>> testaaa
>>> @document.get(''x/x1'').collect {|e|
e.get(''n'').collect {|n| puts n.text}}
test

Why am I getting a XmlElement object? How can I access my xml in a
cleaner fashion?


My second problem, I wanted to be able to pass in a block

  def get(xpath)
    @document.SelectNodes(xpath).collect {yield}
  end

In this case, I get the following error:
>>> @document.get(''x'') {|n| puts n.text}
:1: undefined method `text'' for nil:NilClass (NoMethodError)
        from xml.rb:27:in `get''

I changed it to  {|n| yield}, but I get the same error.  The object is
always nil. What am I doing wrong?

Hope this all makes sense.

Thanks

Ben

I wrote something similar a while ago

http://github.com/casualjim/ironnails/tree/master/IronNails/vendor/iron_nails/lib/iron_xml.rb

statuses = []
IronXml.parse(''friends_timeline.xml'', :document) do |doc|
  doc.elements(''statuses'') do |status|
    st = Status.new
    st.id = status.element(''id'').value
    st.created_at = status.element(''created_at'').value
    st.text = status.element(''text'').value
    st.source = status.element(''source'').value
    st.truncated = status.element(''truncated'').value
    st.in_reply_to_status_id =
status.element(''in_reply_to_status_id'').value
    st.in_reply_to_user_id =
status.element(''in_reply_to_user_id'').value
    st.favorited = status.element(''favorited'').value
    status.elements(''user'') do |user|
      # process user here
    end

    statuses << st
  end
end

or

statuses = []
IronXml.parse(''friends_timeline.xml'', :document) do |doc|
  doc.statuses do |status|
    st = Status.new
    st.id = status.id
    st.created_at = status.created_at
    st.text = status.text
    st.source = status.source
    st.truncated = status.truncated
    st.in_reply_to_status_id = status.in_reply_to_status_id
    st.in_reply_to_user_id = status.in_reply_to_user_id
    st.favorited = status.favorited
    status.user do |user|
      # process user here
    end

    statuses << st
  end
end


You can maybe look there for inspiration :)

On Thu, Jan 1, 2009 at 6:48 PM, Ben Hall <ben2004uk at googlemail.com>
wrote:
> Hello,
>
> I''ve just been playing around with IronRuby and processing some
XML
> from a REST service.  I''ve created this wrapper:
> require ''mscorlib''
> require ''System, Version=2.0.0.0, Culture=neutral,
> PublicKeyToken=b77a5c561934e089''
> include System
> require ''System.Xml, Version=2.0.0.0, Culture=neutral,
> PublicKeyToken=b77a5c561934e089''
> include System::Xml
>
> #Wrapper around .Net XMLDocument to make it easier to query with -
> more like REXML
> class Document
>  def initialize(xml)
>    @document = XmlDocument.new
>    @document.load_xml xml
>  end
>
>  def get(xpath)   #.collect - I want to pass the block in, not have
> to use it on the outside.
>    @document.SelectNodes(xpath)
>  end
> end
>
> class XmlNodeList
>  def get(name)
>    list.select {|e| e.Name == name}
>  end
> end
>
> class XmlElement
>  def get(name)
>      if has_attribute name
>        get_attribute name
>      else
>        get_elements_by_tag_name name
>      end
>  end
>
>  def text
>     inner_text
>  end
> end
>
> My first problem is that I''m getting XmlElement object instead of
> XmlNode from an XmlNodeList.  If I had XmlNode, then I could do
> e[''n''].text - which is what I want.  As a result, my code
to access
> the N element looks like this:
>
> require ''xml''
> @document =
Document.new(''<x><x1><n>test</n><z>aaa</z></x1></x>'')
> @document.get(''x'').collect {|n| puts n.text}
> >> testaaa
>
> >>> @document.get(''x/x1'').collect {|e|
e.get(''n'').collect {|n| puts
> n.text}}
> test
>
> Why am I getting a XmlElement object? How can I access my xml in a
> cleaner fashion?
>
>
> My second problem, I wanted to be able to pass in a block
>
>  def get(xpath)
>    @document.SelectNodes(xpath).collect {yield}
>  end
>
> In this case, I get the following error:
> >>> @document.get(''x'') {|n| puts n.text}
> :1: undefined method `text'' for nil:NilClass (NoMethodError)
>        from xml.rb:27:in `get''
>
> I changed it to  {|n| yield}, but I get the same error.  The object is
> always nil. What am I doing wrong?
>
> Hope this all makes sense.
>
> Thanks
>
> Ben
> _______________________________________________
> Ironruby-core mailing list
> Ironruby-core at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ironruby-core
>
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Excellent!! Thank you.  I was missing select_single_node and &b ;)

Wrapper is now sorted, and I can do:
require ''xml''
@document =
Document.new(''<x><x1><z>test</z><y><q>abc</q></y></x1><x1><z>tester</z><a>testeraaa</a></x1></x>'')

@document.elements(''x/x1'') do |e|
   puts e.get(''z'')
   e.node(''y'') {|y| puts y.get(''q'')}
end

Thanks
Ben


On Thu, Jan 1, 2009 at 6:01 PM, Ivan Porto Carrero <ivan at
flanders.co.nz> wrote:
> I wrote something similar a while ago
>
>
http://github.com/casualjim/ironnails/tree/master/IronNails/vendor/iron_nails/lib/iron_xml.rb
>
> statuses = []
> IronXml.parse(''friends_timeline.xml'', :document) do |doc|
>   doc.elements(''statuses'') do |status|
>     st = Status.new
>     st.id = status.element(''id'').value
>     st.created_at = status.element(''created_at'').value
>     st.text = status.element(''text'').value
>     st.source = status.element(''source'').value
>     st.truncated = status.element(''truncated'').value
>     st.in_reply_to_status_id =
status.element(''in_reply_to_status_id'').value
>     st.in_reply_to_user_id =
status.element(''in_reply_to_user_id'').value
>     st.favorited = status.element(''favorited'').value
>     status.elements(''user'') do |user|
>       # process user here
>     end
>
>     statuses << st
>   end
> end
>
> or
>
> statuses = []
> IronXml.parse(''friends_timeline.xml'', :document) do |doc|
>   doc.statuses do |status|
>     st = Status.new
>     st.id = status.id
>     st.created_at = status.created_at
>     st.text = status.text
>     st.source = status.source
>     st.truncated = status.truncated
>     st.in_reply_to_status_id = status.in_reply_to_status_id
>     st.in_reply_to_user_id = status.in_reply_to_user_id
>     st.favorited = status.favorited
>     status.user do |user|
>       # process user here
>     end
>
>     statuses << st
>   end
> end
>
>
> You can maybe look there for inspiration :)
>
> On Thu, Jan 1, 2009 at 6:48 PM, Ben Hall <ben2004uk at
googlemail.com> wrote:
>>
>> Hello,
>>
>> I''ve just been playing around with IronRuby and processing
some XML
>> from a REST service.  I''ve created this wrapper:
>> require ''mscorlib''
>> require ''System, Version=2.0.0.0, Culture=neutral,
>> PublicKeyToken=b77a5c561934e089''
>> include System
>> require ''System.Xml, Version=2.0.0.0, Culture=neutral,
>> PublicKeyToken=b77a5c561934e089''
>> include System::Xml
>>
>> #Wrapper around .Net XMLDocument to make it easier to query with -
>> more like REXML
>> class Document
>>  def initialize(xml)
>>    @document = XmlDocument.new
>>    @document.load_xml xml
>>  end
>>
>>  def get(xpath)   #.collect - I want to pass the block in, not have
>> to use it on the outside.
>>    @document.SelectNodes(xpath)
>>  end
>> end
>>
>> class XmlNodeList
>>  def get(name)
>>    list.select {|e| e.Name == name}
>>  end
>> end
>>
>> class XmlElement
>>  def get(name)
>>      if has_attribute name
>>        get_attribute name
>>      else
>>        get_elements_by_tag_name name
>>      end
>>  end
>>
>>  def text
>>     inner_text
>>  end
>> end
>>
>> My first problem is that I''m getting XmlElement object instead
of
>> XmlNode from an XmlNodeList.  If I had XmlNode, then I could do
>> e[''n''].text - which is what I want.  As a result, my
code to access
>> the N element looks like this:
>>
>> require ''xml''
>> @document =
Document.new(''<x><x1><n>test</n><z>aaa</z></x1></x>'')
>> @document.get(''x'').collect {|n| puts n.text}
>> >> testaaa
>>
>> >>> @document.get(''x/x1'').collect {|e|
e.get(''n'').collect {|n| puts
>> >>> n.text}}
>> test
>>
>> Why am I getting a XmlElement object? How can I access my xml in a
>> cleaner fashion?
>>
>>
>> My second problem, I wanted to be able to pass in a block
>>
>>  def get(xpath)
>>    @document.SelectNodes(xpath).collect {yield}
>>  end
>>
>> In this case, I get the following error:
>> >>> @document.get(''x'') {|n| puts n.text}
>> :1: undefined method `text'' for nil:NilClass (NoMethodError)
>>        from xml.rb:27:in `get''
>>
>> I changed it to  {|n| yield}, but I get the same error.  The object is
>> always nil. What am I doing wrong?
>>
>> Hope this all makes sense.
>>
>> Thanks
>>
>> Ben
>> _______________________________________________
>> Ironruby-core mailing list
>> Ironruby-core at rubyforge.org
>> http://rubyforge.org/mailman/listinfo/ironruby-core
>
>
> _______________________________________________
> Ironruby-core mailing list
> Ironruby-core at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ironruby-core
>
>