Class: OM::XML::DynamicNode

Inherits:
Object
  • Object
show all
Defined in:
lib/om/xml/dynamic_node.rb

Overview

Provides a natural syntax for using OM Terminologies to access values from xml Documents

Note: All of these examples assume that @article is an instance of OM::Samples::ModsArticle. Look at that file to see the Terminology.

Examples:

Return an array of the value(s) “start page” node(s) from the second issue node within the first journal node

# Using DynamicNode syntax:
@article.journal(0).issue(1).pages.start
# Other ways to perform this query:
@article.find_by_terms({:journal => 0}, {:issue => 1}, :pages, :start)
@article.ng_xml.xpath("//oxns:relatedItem[@type=\"host\"]/oxns:part[2]/extent[@unit="pages"]", {"oxns"=>"http://www.loc.gov/mods/v3"})

Return an NodeSet of the _first titles_ of all journal nodes

# Using DynamicNode syntax:
@article.journal.title(1)
# Other ways to perform this query:
@article.find_by_terms(:journal, {:title => 1})
@article.ng_xml.xpath("//oxns:relatedItem[@type=\"host\"]/oxns:titleInfo/oxns:title[1]", {"oxns"=>"http://www.loc.gov/mods/v3"})

Find all of the titles from all journals & return the first title Node from that NodeSet

# Using DynamicNode syntax:
@article.journal.title[1]
# Other ways to perform this query:
@article.find_by_terms(:journal, :title)[1]
@article.ng_xml.xpath("//oxns:relatedItem[@type=\"host\"]/oxns:titleInfo/oxns:title", {"oxns"=>"http://www.loc.gov/mods/v3"})[1]

Defined Under Namespace

Classes: AddressedNode

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key, index, document, term, parent = nil) ⇒ DynamicNode

TODO a real term object in here would make it easier to lookup



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# File 'lib/om/xml/dynamic_node.rb', line 33

def initialize(key, index, document, term, parent=nil)  ##TODO a real term object in here would make it easier to lookup
  self.key = key
  self.index = index
  @document = document
  self.term = term
  self.parent = parent
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(name, *args, &block) ⇒ Object 



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# File 'lib/om/xml/dynamic_node.rb', line 52

def method_missing(name, *args, &block)
  return new_update_node(name.to_s.chop.to_sym, nil, args) if /=$/.match(name.to_s)
  return new_update_node(name, args.shift, args) if args.length > 1
  child = term_child_by_name(term.nil? ? parent.term : term, name)
  return OM::XML::DynamicNode.new(name, args.first, @document, child, self) if child
  val.send(name, *args, &block)
end

Instance Attribute Details

#addressed_node ⇒ Object

Returns the value of attribute addressed_node.



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# File 'lib/om/xml/dynamic_node.rb', line 32

def addressed_node
  @addressed_node
end

#index ⇒ Object

Returns the value of attribute index.



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# File 'lib/om/xml/dynamic_node.rb', line 32

def index
  @index
end

#key ⇒ Object

Returns the value of attribute key.



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# File 'lib/om/xml/dynamic_node.rb', line 32

def key
  @key
end

#parent ⇒ Object

Returns the value of attribute parent.



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# File 'lib/om/xml/dynamic_node.rb', line 32

def parent
  @parent
end

#term ⇒ Object

Returns the value of attribute term.



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# File 'lib/om/xml/dynamic_node.rb', line 32

def term
  @term
end

Instance Method Details

#!=(other) ⇒ Object 



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# File 'lib/om/xml/dynamic_node.rb', line 112

def !=(other)
  val != other
end

#==(other) ⇒ Object 



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# File 'lib/om/xml/dynamic_node.rb', line 108

def ==(other)
  other == val
end

#delete ⇒ Object 



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# File 'lib/om/xml/dynamic_node.rb', line 100

def delete
  nodeset.delete
end

#eql?(other) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/om/xml/dynamic_node.rb', line 116

def eql?(other)
  self == other
end

#inspect ⇒ Object 



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# File 'lib/om/xml/dynamic_node.rb', line 104

def inspect
  val.inspect
end

#nodeset ⇒ Object 



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# File 'lib/om/xml/dynamic_node.rb', line 94

def nodeset
  query = xpath
  trim_text = !query.index("text()").nil?
  return @document.find_by_xpath(query)
end

#respond_to_missing?(name, include_private = false) ⇒ Boolean

In practice, method_missing will respond 4 different ways: (1) ALL assignment operations are accepted/attempted as new nodes, (2) ANY operation with multiple arguments is accepted/attempted as a new node (w/ index), (3) With an auto-constructed sub DynamicNode object, (4) By handing off to val. This is the only route that will return NoMethodError.

Here we don’t have args, so we cannot handle cases 2 and 3. But we can at least do 1 and 4.

Returns:

  • (Boolean) 


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# File 'lib/om/xml/dynamic_node.rb', line 48

def respond_to_missing?(name, include_private = false)
  /=$/.match(name.to_s) || val.respond_to?(name, include_private) || super
end

#retrieve_addressed_node ⇒ Object

This is very similar to Terminology#retrieve_term, however it expands proxy paths out into their cannonical paths



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# File 'lib/om/xml/dynamic_node.rb', line 148

def retrieve_addressed_node()
   chain = []
   chain += parent.retrieve_addressed_node() if parent
   if (self.index)
     ### This is an index
     node = AddressedNode.new(key, term.xpath_relative, self)
     node.xpath = OM::XML::TermXpathGenerator.add_node_index_predicate(node.xpath, index)
     chain << node
   elsif (term.kind_of? NamedTermProxy)
      proxy = term.proxy_pointer.dup
      first = proxy.shift
      p = @document.class.terminology.retrieve_node(*first)
      chain << AddressedNode.new(p, p.xpath_relative, self)
      while !proxy.empty?
        first = proxy.shift
        p = p.retrieve_term(first)
        chain << AddressedNode.new(p, p.xpath_relative, self)
      end
   else
     chain << AddressedNode.new(key, term.xpath_relative, self)
   end
   chain
end

#to_pointer ⇒ Object 



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# File 'lib/om/xml/dynamic_node.rb', line 120

def to_pointer
  if self.index
    parent.nil? ?  [{key => index}] : parent.to_pointer << {key => index}
  else ### A pointer
    parent.nil? ? [key] : parent.to_pointer << key
  end
end

#val ⇒ Array

This resolves the target of this dynamic node into a reified Array

Returns:

  • (Array) 


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# File 'lib/om/xml/dynamic_node.rb', line 87

def val
  query = xpath
  trim_text = !query.index("text()").nil?
  val = @document.find_by_xpath(query).collect {|node| (trim_text ? node.text.strip : node.text) }
  term.deserialize(val)
end

#val=(args) ⇒ Object 



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# File 'lib/om/xml/dynamic_node.rb', line 60

def val=(args)
  @document.ng_xml_will_change!
  new_values = term.sanitize_new_values(args.first)
  existing_nodes = @document.find_by_xpath(xpath)
  if existing_nodes.length > new_values.length
    starting_index = new_values.length + 1
    starting_index.upto(existing_nodes.size).each do |index|
      @document.term_value_delete select: xpath, child_index: index
    end
  end
  new_values.each_with_index do |z, y|
## If we pass something that already has an index on it, we should be able to add it.
    if existing_nodes[y.to_i].nil?
      parent_pointer = if parent
        parent.to_pointer
      elsif term.is_a? NamedTermProxy
        term.proxy_pointer[0..-2]
      end
      @document.term_values_append(:parent_select=> parent_pointer,:parent_index=>0,:template=>to_pointer,:values=>z)
    else
      @document.term_value_update(xpath, y.to_i, z)
    end
  end
end

#xpath ⇒ Object 



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# File 'lib/om/xml/dynamic_node.rb', line 128

def xpath
  if parent.nil?
    @document.class.terminology.xpath_with_indexes(*(to_pointer << {})) ### last element is always filters
  else
    chain = retrieve_addressed_node( )
    '//' + chain.map { |n| n.xpath}.join('/')
  end
end