JRuby NAMESPACE_ERR when root node has a namespace prefix

[yvesll]

Environment

JRuby: 9.4.3.0
nokogiri (1.15.3 java)
nokogiri-happymapper (0.9.0)

Description

My generated xml loooks like:

<?xml version="1.0" encoding="UTF-8"?>
<namespace:demo xmlns:namespace=URL>
  ......
<namespace:demo>

Ruby code:

require 'happymapper'

class Demo
  include HappyMapper

  register_namespace 'namespace', 'URL'

  tag 'namespace:demo'
end

puts Demo.new.to_xml

It works fine with MRI Ruby, but within JRuby, it reports following errors:

Unhandled Java exception: org.w3c.dom.DOMException: NAMESPACE_ERR: An attempt is made to create or change an object in a way which is incorrect with regard to namespaces.
org.w3c.dom.DOMException: NAMESPACE_ERR: An attempt is made to create or change an object in a way which is incorrect with regard to namespaces.
                 setName at org/apache/xerces/dom/ElementNSImpl:-1
                  <init> at org/apache/xerces/dom/ElementNSImpl:-1
         createElementNS at org/apache/xerces/dom/CoreDocumentImpl:-1
                    init at nokogiri/XmlNode.java:330
                   rbNew at nokogiri/XmlNode.java:277
                    call at nokogiri/XmlNode$INVOKER$s$0$0$rbNew.gen:-1
            cacheAndCall at org/jruby/runtime/callsite/CachingCallSite.java:446
                    call at org/jruby/runtime/callsite/CachingCallSite.java:92
               interpret at org/jruby/ir/instructions/CallBase.java:561
             processCall at org/jruby/ir/interpreter/InterpreterEngine.java:367
               interpret at org/jruby/ir/interpreter/StartupInterpreterEngine.java:66
        INTERPRET_METHOD at org/jruby/internal/runtime/methods/MixedModeIRMethod.java:128
                    call at org/jruby/internal/runtime/methods/MixedModeIRMethod.java:115
            cacheAndCall at org/jruby/runtime/callsite/CachingCallSite.java:446
                    call at org/jruby/runtime/callsite/CachingCallSite.java:92
                callIter at org/jruby/runtime/callsite/CachingCallSite.java:103
               interpret at org/jruby/ir/instructions/CallBase.java:558
             processCall at org/jruby/ir/interpreter/InterpreterEngine.java:367
               interpret at org/jruby/ir/interpreter/StartupInterpreterEngine.java:66
        INTERPRET_METHOD at org/jruby/internal/runtime/methods/MixedModeIRMethod.java:128
                    call at org/jruby/internal/runtime/methods/MixedModeIRMethod.java:115
                    call at org/jruby/runtime/Helpers.java:600
       callMethodMissing at org/jruby/runtime/Helpers.java:117
  finvokeWithRefinements at org/jruby/RubyClass.java:520
                    send at org/jruby/RubyBasicObject.java:1703
                    send at org/jruby/RubyKernel.java:2355
                    call at org/jruby/RubyKernel$INVOKER$s$send.gen:-1
            cacheAndCall at org/jruby/runtime/callsite/CachingCallSite.java:446
                    call at org/jruby/runtime/callsite/CachingCallSite.java:92
                callIter at org/jruby/runtime/callsite/CachingCallSite.java:103
               interpret at org/jruby/ir/instructions/CallBase.java:558
             processCall at org/jruby/ir/interpreter/InterpreterEngine.java:367
               interpret at org/jruby/ir/interpreter/StartupInterpreterEngine.java:66
               interpret at org/jruby/ir/interpreter/InterpreterEngine.java:76
        INTERPRET_METHOD at org/jruby/internal/runtime/methods/MixedModeIRMethod.java:164
                    call at org/jruby/internal/runtime/methods/MixedModeIRMethod.java:151
                    call at org/jruby/internal/runtime/methods/DynamicMethod.java:212
            cacheAndCall at org/jruby/runtime/callsite/CachingCallSite.java:456
                    call at org/jruby/runtime/callsite/CachingCallSite.java:195
     invokeOther5:to_xml at nokogiri.rb:11
             RUBY$script at nokogiri.rb:11
                     run at nokogiri.rb:-1
     invokeWithArguments at java/lang/invoke/MethodHandle.java:710
                    load at org/jruby/ir/Compiler.java:114
               runScript at org/jruby/Ruby.java:1276
             runNormally at org/jruby/Ruby.java:1193
             runNormally at org/jruby/Ruby.java:1175
             runNormally at org/jruby/Ruby.java:1211
             runFromMain at org/jruby/Ruby.java:989
           doRunFromMain at org/jruby/Main.java:398
             internalRun at org/jruby/Main.java:282
                     run at org/jruby/Main.java:227
                    main at org/jruby/Main.java:199

I guess that the user cannot send a node with a namespace before adding the definition of the namespace.
I applied a workaround in the to_xml method and it works:

def to_xml(builder = nil, default_namespace = nil, namespace_override = nil,
             tag_from_parent = nil)
    
    <code>

    root_tag = "#{tag_from_parent || self.class.tag_name}_"
    if root_tag.include?(':')
      namespace, tag = root_tag.split(':')
      namespace_name ||= namespace
      root_tag = tag
    end
    builder.send(root_tag, attributes) do |xml|

    <code>
end

[mvz]

It seems this only works with MRI by accident. The way to specify a namespace for a Class' tag is with the namespace method. So the Demo class would look like this:

class Demo
  include HappyMapper

  register_namespace 'namespace', 'URL'

  tag 'demo'
  namespace 'namespace'
end

This version works with both MRI and JRuby.

I'm going to add a check to prevent tags that include : characters.

[yvesll]

HI, @mvz, thanks for the explanation. But how can I setup to only add a namespace prefix for the tag 'demo' but not for child nodes?

[mvz]

@yvesll coincidentally, someone else just asked the same question: #223. I'm going to investigate and answer it there.