Class REXML::Element
In: lib/rexml/element.rb
Parent: Parent

Represents a tagged XML element. Elements are characterized by having children, attributes, and names, and can themselves be children.

Methods

Included Modules

Namespace

Constants

UNDEFINED = "UNDEFINED";

Attributes

attributes  [R]  Mechanisms for accessing attributes and child elements of this element.
context  [RW]  The context holds information about the processing environment, such as whitespace handling.
elements  [R]  Mechanisms for accessing attributes and child elements of this element.

Public Class methods

Constructor

arg:if not supplied, will be set to the default value. If a String, the name of this object will be set to the argument. If an Element, the object will be shallowly cloned; name, attributes, and namespaces will be copied. Children will not be copied.
parent:if supplied, must be a Parent, and will be used as the parent of this object.
context:If supplied, must be a hash containing context items. Context items include:
  • :respect_whitespace the value of this is :all or an array of strings being the names of the elements to respect whitespace for. Defaults to :all.
  • :compress_whitespace the value can be :all or an array of strings being the names of the elements to ignore whitespace on. Overrides :respect_whitespace.
  • :ignore_whitespace_nodes the value can be :all or an array of strings being the names of the elements in which to ignore whitespace-only nodes. If this is set, Text nodes which contain only whitespace will not be added to the document tree.
  • :raw can be :all, or an array of strings being the names of the elements to process in raw mode. In raw mode, special characters in text is not converted to or from entities.

[Source]

    # File lib/rexml/element.rb, line 58
58:     def initialize( arg = UNDEFINED, parent=nil, context=nil )
59:       super(parent)
60: 
61:       @elements = Elements.new(self)
62:       @attributes = Attributes.new(self)
63:       @context = context
64: 
65:       if arg.kind_of? String
66:         self.name = arg
67:       elsif arg.kind_of? Element
68:         self.name = arg.expanded_name
69:         arg.attributes.each_attribute{ |attribute|
70:           @attributes << Attribute.new( attribute )
71:         }
72:         @context = arg.context
73:       end
74:     end

Public Instance methods

Adds an attribute to this element, overwriting any existing attribute by the same name.

key:can be either an Attribute or a String. If an Attribute, the attribute is added to the list of Element attributes. If String, the argument is used as the name of the new attribute, and the value parameter must be supplied.
value:Required if key is a String, and ignored if the first argument is an Attribute. This is a String, and is used as the value of the new Attribute. This should be the unnormalized value of the attribute (without entities).
Returns:the Attribute added
 e = Element.new 'e'
 e.add_attribute( 'a', 'b' )               #-> <e a='b'/>
 e.add_attribute( 'x:a', 'c' )             #-> <e a='b' x:a='c'/>
 e.add_attribute Attribute.new('b', 'd')   #-> <e a='b' x:a='c' b='d'/>

[Source]

     # File lib/rexml/element.rb, line 583
583:     def add_attribute( key, value=nil )
584:       if key.kind_of? Attribute
585:         @attributes << key
586:       else
587:         @attributes[key] = value
588:       end
589:     end

Add multiple attributes to this element.

hash:is either a hash, or array of arrays
 el.add_attributes( {"name1"=>"value1", "name2"=>"value2"} )
 el.add_attributes( [ ["name1","value1"], ["name2"=>"value2"] ] )

[Source]

     # File lib/rexml/element.rb, line 595
595:     def add_attributes hash
596:       if hash.kind_of? Hash
597:         hash.each_pair {|key, value| @attributes[key] = value }
598:       elsif hash.kind_of? Array
599:         hash.each { |value| @attributes[ value[0] ] = value[1] }
600:       end
601:     end

Adds a child to this element, optionally setting attributes in the element.

element:optional. If Element, the element is added. Otherwise, a new Element is constructed with the argument (see Element.initialize).
attrs:If supplied, must be a Hash containing String name,value pairs, which will be used to set the attributes of the new Element.
Returns:the Element that was added
 el = doc.add_element 'my-tag'
 el = doc.add_element 'my-tag', {'attr1'=>'val1', 'attr2'=>'val2'}
 el = Element.new 'my-tag'
 doc.add_element el

[Source]

     # File lib/rexml/element.rb, line 295
295:     def add_element element, attrs=nil
296:       raise "First argument must be either an element name, or an Element object" if element.nil?
297:       el = @elements.add(element)
298:       attrs.each do |key, value|
299:         el.attributes[key]=Attribute.new(key,value,self)
300:       end       if attrs.kind_of? Hash
301:       el
302:     end

Adds a namespace to this element.

prefix:the prefix string, or the namespace URI if uri is not supplied
uri:the namespace URI. May be nil, in which prefix is used as the URI

Evaluates to: this Element

 a = Element.new("a")
 a.add_namespace("xmlns:foo", "bar" )
 a.add_namespace("foo", "bar")  # shorthand for previous line
 a.add_namespace("twiddle")
 puts a   #-> <a xmlns:foo='bar' xmlns='twiddle'/>

[Source]

     # File lib/rexml/element.rb, line 250
250:     def add_namespace( prefix, uri=nil )
251:       unless uri
252:         @attributes["xmlns"] = prefix
253:       else
254:         prefix = "xmlns:#{prefix}" unless prefix =~ /^xmlns:/
255:         @attributes[ prefix ] = uri
256:       end
257:       self
258:     end

A helper method to add a Text child. Actual Text instances can be added with regular Parent methods, such as add() and <<()

text:if a String, a new Text instance is created and added to the parent. If Text, the object is added directly.
Returns:this Element
 e = Element.new('a')          #-> <e/>
 e.add_text 'foo'              #-> <e>foo</e>
 e.add_text Text.new(' bar')    #-> <e>foo bar</e>

Note that at the end of this example, the branch has 3 nodes; the ‘e’ element and 2 Text node children.

[Source]

     # File lib/rexml/element.rb, line 522
522:     def add_text( text )
523:       if text.kind_of? String 
524:         if @children[-1].kind_of? Text
525:           @children[-1] << text
526:           return
527:         end
528:         text = Text.new( text, whitespace(), nil, raw() )
529:       end
530:       self << text unless text.nil?
531:       return self
532:     end

Attributes #

[Source]

     # File lib/rexml/element.rb, line 553
553:     def attribute( name, namespace=nil )
554:       prefix = nil
555:       prefix = namespaces.index(namespace) if namespace
556:       prefix = nil if prefix == 'xmlns'
557:       attributes.get_attribute( "#{prefix ? prefix + ':' : ''}#{name}" )
558:     end

Get an array of all CData children. IMMUTABLE

[Source]

     # File lib/rexml/element.rb, line 627
627:     def cdatas
628:       find_all { |child| child.kind_of? CData }.freeze
629:     end

Creates a shallow copy of self.

  d = Document.new "<a><b/><b/><c><d/></c></a>"
  new_a = d.root.clone
  puts new_a  # => "<a/>"

[Source]

    # File lib/rexml/element.rb, line 96
96:     def clone
97:       self.class.new self
98:     end

Get an array of all Comment children. IMMUTABLE

[Source]

     # File lib/rexml/element.rb, line 633
633:     def comments
634:       find_all { |child| child.kind_of? Comment }.freeze
635:     end

Removes an attribute

key:either an Attribute or a String. In either case, the attribute is found by matching the attribute name to the argument, and then removed. If no attribute is found, no action is taken.
Returns:the attribute removed, or nil if this Element did not contain a matching attribute
 e = Element.new('E')
 e.add_attribute( 'name', 'Sean' )             #-> <E name='Sean'/>
 r = e.add_attribute( 'sur:name', 'Russell' )  #-> <E name='Sean' sur:name='Russell'/>
 e.delete_attribute( 'name' )                  #-> <E sur:name='Russell'/>
 e.delete_attribute( r )                       #-> <E/>

[Source]

     # File lib/rexml/element.rb, line 616
616:     def delete_attribute(key)
617:       attr = @attributes.get_attribute(key)
618:       attr.remove unless attr.nil?
619:     end

Deletes a child element.

element:Must be an Element, String, or Integer. If Element, the element is removed. If String, the element is found (via XPath) and removed. <em>This means that any parent can remove any descendant.<em> If Integer, the Element indexed by that number will be removed.
Returns:the element that was removed.
 doc.delete_element "/a/b/c[@id='4']"
 doc.delete_element doc.elements["//k"]
 doc.delete_element 1

[Source]

     # File lib/rexml/element.rb, line 315
315:     def delete_element element
316:       @elements.delete element
317:     end

Removes a namespace from this node. This only works if the namespace is actually declared in this node. If no argument is passed, deletes the default namespace.

Evaluates to: this element

 doc = Document.new "<a xmlns:foo='bar' xmlns='twiddle'/>"
 doc.root.delete_namespace
 puts doc     # -> <a xmlns:foo='bar'/>
 doc.root.delete_namespace 'foo'
 puts doc     # -> <a/>

[Source]

     # File lib/rexml/element.rb, line 270
270:     def delete_namespace namespace="xmlns"
271:       namespace = "xmlns:#{namespace}" unless namespace == 'xmlns'
272:       attribute = attributes.get_attribute(namespace)
273:       attribute.remove unless attribute.nil?
274:       self
275:     end

Evaluates to the document to which this element belongs, or nil if this element doesn‘t belong to a document.

[Source]

     # File lib/rexml/element.rb, line 131
131:     def document
132:       rt = root
133:       rt.parent if rt
134:     end

Synonym for Element.elements.each

[Source]

     # File lib/rexml/element.rb, line 392
392:     def each_element( xpath=nil, &block ) # :yields: Element
393:       @elements.each( xpath, &block )
394:     end

Iterates through the child elements, yielding for each Element that has a particular attribute set.

key:the name of the attribute to search for
value:the value of the attribute
max:(optional) causes this method to return after yielding for this number of matching children
name:(optional) if supplied, this is an XPath that filters the children to check.
 doc = Document.new "<a><b @id='1'/><c @id='2'/><d @id='1'/><e/></a>"
 # Yields b, c, d
 doc.root.each_element_with_attribute( 'id' ) {|e| p e}
 # Yields b, d
 doc.root.each_element_with_attribute( 'id', '1' ) {|e| p e}
 # Yields b
 doc.root.each_element_with_attribute( 'id', '1', 1 ) {|e| p e}
 # Yields d
 doc.root.each_element_with_attribute( 'id', '1', 0, 'd' ) {|e| p e}

[Source]

     # File lib/rexml/element.rb, line 350
350:     def each_element_with_attribute( key, value=nil, max=0, name=nil, &block ) # :yields: Element
351:       each_with_something( proc {|child| 
352:         if value.nil?
353:           child.attributes[key] != nil
354:         else
355:           child.attributes[key]==value
356:         end
357:       }, max, name, &block )
358:     end

Iterates through the children, yielding for each Element that has a particular text set.

text:the text to search for. If nil, or not supplied, will iterate over all Element children that contain at least one Text node.
max:(optional) causes this method to return after yielding for this number of matching children
name:(optional) if supplied, this is an XPath that filters the children to check.
 doc = Document.new '<a><b>b</b><c>b</c><d>d</d><e/></a>'
 # Yields b, c, d
 doc.each_element_with_text {|e|p e}
 # Yields b, c
 doc.each_element_with_text('b'){|e|p e}
 # Yields b
 doc.each_element_with_text('b', 1){|e|p e}
 # Yields d
 doc.each_element_with_text(nil, 0, 'd'){|e|p e}

[Source]

     # File lib/rexml/element.rb, line 381
381:     def each_element_with_text( text=nil, max=0, name=nil, &block ) # :yields: Element
382:       each_with_something( proc {|child| 
383:         if text.nil?
384:           child.has_text?
385:         else
386:           child.text == text
387:         end
388:       }, max, name, &block )
389:     end

Synonym for Element.to_a This is a little slower than calling elements.each directly.

xpath:any XPath by which to search for elements in the tree
Returns:an array of Elements that match the supplied path

[Source]

     # File lib/rexml/element.rb, line 400
400:     def get_elements( xpath )
401:       @elements.to_a( xpath )
402:     end

Returns the first child Text node, if any, or nil otherwise. This method returns the actual Text node, rather than the String content.

 doc = Document.new "<p>some text <b>this is bold!</b> more text</p>"
 # The element 'p' has two text elements, "some text " and " more text".
 doc.root.get_text.value            #-> "some text "

[Source]

     # File lib/rexml/element.rb, line 461
461:     def get_text path = nil
462:       rv = nil
463:       if path
464:         element = @elements[ path ]
465:         rv = element.get_text unless element.nil?
466:       else
467:         rv = @children.find { |node| node.kind_of? Text }
468:       end
469:       return rv
470:     end

Evaluates to true if this element has any attributes set, false otherwise.

[Source]

     # File lib/rexml/element.rb, line 562
562:     def has_attributes?
563:       return !@attributes.empty?
564:     end

Evaluates to true if this element has at least one child Element

 doc = Document.new "<a><b/><c>Text</c></a>"
 doc.root.has_elements               # -> true
 doc.elements["/a/b"].has_elements   # -> false
 doc.elements["/a/c"].has_elements   # -> false

[Source]

     # File lib/rexml/element.rb, line 324
324:     def has_elements?
325:       !@elements.empty?
326:     end

Evaluates to true if this element has at least one Text child

[Source]

     # File lib/rexml/element.rb, line 432
432:     def has_text?
433:       not text().nil?
434:     end

[Source]

     # File lib/rexml/element.rb, line 161
161:     def ignore_whitespace_nodes
162:       @ignore_whitespace_nodes = false
163:       if @context
164:         if @context[:ignore_whitespace_nodes]
165:           @ignore_whitespace_nodes = 
166:             (@context[:ignore_whitespace_nodes] == :all or
167:              @context[:ignore_whitespace_nodes].include? expanded_name)
168:         end
169:       end
170:     end

[Source]

    # File lib/rexml/element.rb, line 76
76:     def inspect
77:       rv = "<#@expanded_name"
78: 
79:       @attributes.each_attribute do |attr|
80:         rv << " "
81:         attr.write( rv, 0 )
82:       end
83: 
84:       if children.size > 0
85:         rv << "> ... </>"
86:       else
87:         rv << "/>"
88:       end
89:     end

Get an array of all Instruction children. IMMUTABLE

[Source]

     # File lib/rexml/element.rb, line 639
639:     def instructions
640:       find_all { |child| child.kind_of? Instruction }.freeze
641:     end

Evalutas to the URI for a prefix, or the empty string if no such namespace is declared for this element. Evaluates recursively for ancestors. Returns the default namespace, if there is one.

prefix:the prefix to search for. If not supplied, returns the default namespace if one exists
Returns:the namespace URI as a String, or nil if no such namespace exists. If the namespace is undefined, returns an empty string
 doc = Document.new("<a xmlns='1' xmlns:y='2'><b/><c xmlns:z='3'/></a>")
 b = doc.elements['//b']
 b.namespace           # -> '1'
 b.namespace("y")      # -> '2'

[Source]

     # File lib/rexml/element.rb, line 222
222:     def namespace(prefix=nil)
223:       if prefix.nil?
224:         prefix = prefix()
225:       end
226:       if prefix == ''
227:         prefix = "xmlns"
228:       else
229:         prefix = "xmlns:#{prefix}" unless prefix[0,5] == 'xmlns'
230:       end
231:       ns = attributes[ prefix ]
232:       ns = parent.namespace(prefix) if ns.nil? and parent
233:       ns = '' if ns.nil? and prefix == 'xmlns'
234:       return ns
235:     end

[Source]

     # File lib/rexml/element.rb, line 202
202:     def namespaces
203:       namespaces = {}
204:       namespaces = parent.namespaces if parent
205:       namespaces = namespaces.merge( attributes.namespaces )
206:       return namespaces
207:     end

Returns the next sibling that is an element, or nil if there is no Element sibling after this one

 doc = Document.new '<a><b/>text<c/></a>'
 doc.root.elements['b'].next_element          #-> <c/>
 doc.root.elements['c'].next_element          #-> nil

[Source]

     # File lib/rexml/element.rb, line 409
409:     def next_element
410:       element = next_sibling
411:       element = element.next_sibling until element.nil? or element.kind_of? Element 
412:       return element
413:     end

[Source]

     # File lib/rexml/element.rb, line 534
534:     def node_type
535:       :element
536:     end

Evaluates to an Array containing the prefixes (names) of all defined namespaces at this context node.

 doc = Document.new("<a xmlns:x='1' xmlns:y='2'><b/><c xmlns:z='3'/></a>")
 doc.elements['//b'].prefixes # -> ['x', 'y']

[Source]

     # File lib/rexml/element.rb, line 195
195:     def prefixes
196:       prefixes = []
197:       prefixes = parent.prefixes if parent
198:       prefixes |= attributes.prefixes
199:       return prefixes
200:     end

Returns the previous sibling that is an element, or nil if there is no Element sibling prior to this one

 doc = Document.new '<a><b/>text<c/></a>'
 doc.root.elements['c'].previous_element          #-> <b/>
 doc.root.elements['b'].previous_element          #-> nil

[Source]

     # File lib/rexml/element.rb, line 420
420:     def previous_element
421:       element = previous_sibling
422:       element = element.previous_sibling until element.nil? or element.kind_of? Element
423:       return element
424:     end

Evaluates to true if raw mode is set for this element. This is the case if the context has :raw set to :all or an array containing the name of this element.

The evaluation is tested against expanded_name, and so is namespace sensitive.

[Source]

     # File lib/rexml/element.rb, line 178
178:     def raw
179:       @raw = (@context and @context[:raw] and
180:               (@context[:raw] == :all or
181:                @context[:raw].include? expanded_name))
182:                @raw
183:     end

[Source]

     # File lib/rexml/element.rb, line 123
123:     def root
124:       return elements[1] if self.kind_of? Document
125:       return self if parent.kind_of? Document or parent.nil?
126:       return parent.root
127:     end

Evaluates to the root node of the document that this element belongs to. If this element doesn‘t belong to a document, but does belong to another Element, the parent‘s root will be returned, until the earliest ancestor is found.

Note that this is not the same as the document element. In the following example, <a> is the document element, and the root node is the parent node of the document element. You may ask yourself why the root node is useful: consider the doctype and XML declaration, and any processing instructions before the document element… they are children of the root node, or siblings of the document element. The only time this isn‘t true is when an Element is created that is not part of any Document. In this case, the ancestor that has no parent acts as the root node.

 d = Document.new '<a><b><c/></b></a>'
 a = d[1] ; c = a[1][1]
 d.root_node == d   # TRUE
 a.root_node        # namely, d
 c.root_node        # again, d

[Source]

     # File lib/rexml/element.rb, line 119
119:     def root_node
120:       parent.nil? ? self : parent.root_node
121:     end

A convenience method which returns the String value of the first child text element, if one exists, and nil otherwise.

Note that an element may have multiple Text elements, perhaps separated by other children. Be aware that this method only returns the first Text node.

This method returns the value of the first text child node, which ignores the raw setting, so always returns normalized text. See the Text::value documentation.

 doc = Document.new "<p>some text <b>this is bold!</b> more text</p>"
 # The element 'p' has two text elements, "some text " and " more text".
 doc.root.text              #-> "some text "

[Source]

     # File lib/rexml/element.rb, line 450
450:     def text( path = nil )
451:       rv = get_text(path)
452:       return rv.value unless rv.nil?
453:       nil
454:     end

Sets the first Text child of this object. See text() for a discussion about Text children.

If a Text child already exists, the child is replaced by this content. This means that Text content can be deleted by calling this method with a nil argument. In this case, the next Text child becomes the first Text child. In no case is the order of any siblings disturbed.

text:If a String, a new Text child is created and added to this Element as the first Text child. If Text, the text is set as the first Child element. If nil, then any existing first Text child is removed.
Returns:this Element.
 doc = Document.new '<a><b/></a>'
 doc.root.text = 'Sean'      #-> '<a><b/>Sean</a>'
 doc.root.text = 'Elliott'   #-> '<a><b/>Elliott</a>'
 doc.root.add_element 'c'    #-> '<a><b/>Elliott<c/></a>'
 doc.root.text = 'Russell'   #-> '<a><b/>Russell<c/></a>'
 doc.root.text = nil         #-> '<a><b/><c/></a>'

[Source]

     # File lib/rexml/element.rb, line 492
492:     def text=( text )
493:       if text.kind_of? String
494:         text = Text.new( text, whitespace(), nil, raw() )
495:       elsif !text.nil? and !text.kind_of? Text
496:         text = Text.new( text.to_s, whitespace(), nil, raw() )
497:       end
498:       old_text = get_text
499:       if text.nil?
500:         old_text.remove unless old_text.nil?
501:       else
502:         if old_text.nil?
503:           self << text
504:         else
505:           old_text.replace_with( text )
506:         end
507:       end
508:       return self
509:     end

Get an array of all Text children. IMMUTABLE

[Source]

     # File lib/rexml/element.rb, line 645
645:     def texts
646:       find_all { |child| child.kind_of? Text }.freeze
647:     end

Evaluates to true if whitespace is respected for this element. This is the case if:

  1. Neither :respect_whitespace nor :compress_whitespace has any value
  2. The context has :respect_whitespace set to :all or an array containing the name of this element, and :compress_whitespace isn‘t set to :all or an array containing the name of this element.

The evaluation is tested against expanded_name, and so is namespace sensitive.

[Source]

     # File lib/rexml/element.rb, line 145
145:     def whitespace
146:       @whitespace = nil
147:       if @context
148:         if @context[:respect_whitespace]
149:           @whitespace = (@context[:respect_whitespace] == :all or
150:                          @context[:respect_whitespace].include? expanded_name)
151:         end
152:         @whitespace = false if (@context[:compress_whitespace] and
153:                                 (@context[:compress_whitespace] == :all or
154:                                  @context[:compress_whitespace].include? expanded_name)
155:                                )
156:       end
157:       @whitespace = true unless @whitespace == false
158:       @whitespace
159:     end

DEPRECATED

See REXML::Formatters

Writes out this element, and recursively, all children.

output:output an object which supports ’<< string’; this is where the
  document will be written.
indent:An integer. If -1, no indenting will be used; otherwise, the indentation will be this number of spaces, and children will be indented an additional amount. Defaults to -1
transitive:If transitive is true and indent is >= 0, then the output will be pretty-printed in such a way that the added whitespace does not affect the parse tree of the document
ie_hack:Internet Explorer is the worst piece of crap to have ever been written, with the possible exception of Windows itself. Since IE is unable to parse proper XML, we have to provide a hack to generate XML that IE‘s limited abilities can handle. This hack inserts a space before the /> on empty tags. Defaults to false
 out = ''
 doc.write( out )     #-> doc is written to the string 'out'
 doc.write( $stdout ) #-> doc written to the console

[Source]

     # File lib/rexml/element.rb, line 674
674:     def write(writer=$stdout, indent=-1, transitive=false, ie_hack=false)
675:       Kernel.warn("#{self.class.name}.write is deprecated.  See REXML::Formatters")
676:       formatter = if indent > -1
677:           if transitive
678:             REXML::Formatters::Transitive.new( indent, ie_hack )
679:           else
680:             REXML::Formatters::Pretty.new( indent, ie_hack )
681:           end
682:         else
683:           REXML::Formatters::Default.new( ie_hack )
684:         end
685:       formatter.write( self, output )
686:     end

[Source]

     # File lib/rexml/element.rb, line 538
538:     def xpath
539:       path_elements = []
540:       cur = self
541:       path_elements << __to_xpath_helper( self )
542:       while cur.parent
543:         cur = cur.parent
544:         path_elements << __to_xpath_helper( cur )
545:       end
546:       return path_elements.reverse.join( "/" )
547:     end

Private Instance methods

[Source]

     # File lib/rexml/element.rb, line 690
690:     def __to_xpath_helper node
691:       rv = node.expanded_name.clone
692:       if node.parent
693:         results = node.parent.find_all {|n| 
694:           n.kind_of?(REXML::Element) and n.expanded_name == node.expanded_name 
695:         }
696:         if results.length > 1
697:           idx = results.index( node )
698:           rv << "[#{idx+1}]"
699:         end
700:       end
701:       rv
702:     end

A private helper method

[Source]

     # File lib/rexml/element.rb, line 705
705:     def each_with_something( test, max=0, name=nil )
706:       num = 0
707:       child=nil
708:       @elements.each( name ){ |child|
709:         yield child if test.call(child) and num += 1
710:         return if max>0 and num == max
711:       }
712:     end

[Validate]