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Class Element¶ ↑

Class Element has methods from its superclasses and included modules; see:

• Tasks for Parent.

• Tasks for Child.

• Tasks for Node.

• Module Enumerable.

:include: ../tocs/element_toc.rdoc

New Element¶ ↑

Task: Create a Default Element¶ ↑

Use method Element::new with no arguments to create a default element:

e = REXML::Element.new e.name # => “UNDEFINED” e.parent # => nil e.context # => nil

Task: Create a Named Element¶ ↑

Use method Element::new with a string name argument to create a named element:

e = REXML::Element.new(‘foo’) e.name # => “foo” e.parent # => nil e.context # => nil

Task: Create an Element with Name and Parent¶ ↑

Use method Element::new with name and parent arguments to create an element with name and parent:

p = REXML::Parent.new e = REXML::Element.new(‘foo’, p) e.name # => “foo” e.parent # => #<REXML::Parent @parent=nil, @children=> e.context # => nil

Task: Create an Element with Name, Parent, and Context¶ ↑

Use method Element::new with name, parent, and context arguments to create an element with name, parent, and context:

p = REXML::Parent.new e = REXML::Element.new(‘foo’, p, {compress_whitespace: :all}) e.name # => “foo” e.parent # => #<REXML::Parent @parent=nil, @children=> e.context # => {:compress_whitespace=>:all}

Task: Create a Shallow Clone¶ ↑

Use method Element#clone to create a shallow clone of an element, copying only the name, attributes, and context:

e0 = REXML::Element.new(‘foo’, nil, {compress_whitespace: :all}) e0.add_attribute(REXML::Attribute.new(‘bar’, ‘baz’)) e0.context = {compress_whitespace: :all} e1 = e0.clone # => <foo bar=‘baz’/> e1.name # => “foo” e1.context # => {:compress_whitespace=>:all}

Attributes¶ ↑

Task: Create and Add an Attribute¶ ↑

Use method Element#add_attribute to create and add an attribute:

e = REXML::Element.new e.add_attribute(‘attr’, ‘value’) # => “value” e # => “value” e.add_attribute(‘attr’, ‘VALUE’) # => “VALUE” e # => “VALUE”

Task: Add an Existing Attribute¶ ↑

Use method Element#add_attribute to add an existing attribute:

e = REXML::Element.new a = REXML::Attribute.new(‘attr’, ‘value’) e.add_attribute(a) e # => “value” a = REXML::Attribute.new(‘attr’, ‘VALUE’) e.add_attribute(a) e # => “VALUE”

Task: Add Multiple Attributes from a Hash¶ ↑

Use method Element#add_attributes to add multiple attributes from a hash:

e = REXML::Element.new h = {‘foo’ => 0, ‘bar’ => 1} e.add_attributes(h) e # => “0” e # => “1”

Task: Add Multiple Attributes from an Array¶ ↑

Use method Element#add_attributes to add multiple attributes from an array:

e = REXML::Element.new a = 'foo', 0], ['bar', 1 e.add_attributes(a) e # => “0” e # => “1”

Task: Retrieve the Value for an Attribute Name¶ ↑

Use method Element#[] to retrieve the value for an attribute name:

e = REXML::Element.new e.add_attribute(‘attr’, ‘value’) # => “value” e # => “value”

Task: Retrieve the Attribute Value for a Name and Namespace¶ ↑

Use method Element#attribute to retrieve the value for an attribute name:

xml_string = “<root xmlns:a=‘a’ a:x=‘a:x’ x=‘x’/>” d = REXML::Document.new(xml_string) e = d.root e.attribute(“x”) # => x=‘x’ e.attribute(“x”, “a”) # => a:x=‘a:x’

Task: Delete an Attribute¶ ↑

Use method Element#delete_attribute to remove an attribute:

e = REXML::Element.new(‘foo’) e.add_attribute(‘bar’, ‘baz’) e.delete_attribute(‘bar’) e.delete_attribute(‘bar’) e # => nil

Task: Determine Whether the Element Has Attributes¶ ↑

Use method Element#has_attributes? to determine whether the element has attributes:

e = REXML::Element.new(‘foo’) e.has_attributes? # => false e.add_attribute(‘bar’, ‘baz’) e.has_attributes? # => true

Children¶ ↑

Element Children

Task: Create and Add an Element¶ ↑

Use method Element#add_element to create a new element and add it to this element:

e0 = REXML::Element.new(‘foo’) e0.add_element(‘bar’) e0.children # => [<bar/>]

Task: Add an Existing Element¶ ↑

Use method Element#add_element to add an element to this element:

e0 = REXML::Element.new(‘foo’) e1 = REXML::Element.new(‘bar’) e0.add_element(e1) e0.children # => [<bar/>]

Task: Create and Add an Element with Attributes¶ ↑

Use method Element#add_element to create a new element with attributes, and add it to this element:

e0 = REXML::Element.new(‘foo’) e0.add_element(‘bar’, {‘name’ => ‘value’}) e0.children # => [<bar name=‘value’/>]

Task: Add an Existing Element with Added Attributes¶ ↑

Use method Element#add_element to add an element to this element:

e0 = REXML::Element.new(‘foo’) e1 = REXML::Element.new(‘bar’) e0.add_element(e1, {‘name’ => ‘value’}) e0.children # => [<bar name=‘value’/>]

Task: Delete a Specified Element¶ ↑

Use method Element#delete_element to remove a specified element from this element:

e0 = REXML::Element.new(‘foo’) e1 = REXML::Element.new(‘bar’) e0.add_element(e1) e0.children # => [<bar/>] e0.delete_element(e1) e0.children # => []

Task: Delete an Element by Index¶ ↑

Use method Element#delete_element to remove an element from this element by index:

e0 = REXML::Element.new(‘foo’) e1 = REXML::Element.new(‘bar’) e0.add_element(e1) e0.children # => [<bar/>] e0.delete_element(1) e0.children # => []

Task: Delete an Element by XPath¶ ↑

Use method Element#delete_element to remove an element from this element by XPath:

e0 = REXML::Element.new(‘foo’) e1 = REXML::Element.new(‘bar’) e0.add_element(e1) e0.children # => [<bar/>] e0.delete_element(‘//bar/’) e0.children # => []

Task: Determine Whether Element Children¶ ↑

Use method Element#has_elements? to determine whether the element has element children:

e0 = REXML::Element.new(‘foo’) e0.has_elements? # => false e0.add_element(REXML::Element.new(‘bar’)) e0.has_elements? # => true

Task: Get Element Descendants by XPath¶ ↑

Use method Element#get_elements to fetch all element descendant children by XPath:

xml_string = <<-EOT <root> <a level=‘1’> <a level=‘2’/> </a> </root> EOT d = REXML::Document.new(xml_string) d.root.get_elements(‘//a’) # => [<a level=‘1’> … </>, <a level=‘2’/>]

Task: Get Next Element Sibling¶ ↑

Use method Element#next_element to retrieve the next element sibling:

d = REXML::Document.new ‘<a><b/>text<c/></a>’ d.root.elements.next_element #-> <c/> d.root.elements.next_element #-> nil

Task: Get Previous Element Sibling¶ ↑

Use method Element#previous_element to retrieve the previous element sibling:

d = REXML::Document.new ‘<a><b/>text<c/></a>’ d.root.elements.previous_element #-> <b/> d.root.elements.previous_element #-> nil

Text Children

Task: Add a Text Node¶ ↑

Use method Element#add_text to add a text node to the element:

d = REXML::Document.new(‘<a>foo<b/>bar</a>’) e = d.root e.add_text(REXML::Text.new(‘baz’)) e.to_a # => [“foo”, <b/>, “bar”, “baz”] e.add_text(REXML::Text.new(‘baz’)) e.to_a # => [“foo”, <b/>, “bar”, “baz”, “baz”]

Task: Replace the First Text Node¶ ↑

Use method Element#text= to replace the first text node in the element:

d = REXML::Document.new(‘<root><a/>text<b/>more<c/></root>’) e = d.root e.to_a # => [<a/>, “text”, <b/>, “more”, <c/>] e.text = ‘oops’ e.to_a # => [<a/>, “oops”, <b/>, “more”, <c/>]

Task: Remove the First Text Node¶ ↑

Use method Element#text= to remove the first text node in the element:

d = REXML::Document.new(‘<root><a/>text<b/>more<c/></root>’) e = d.root e.to_a # => [<a/>, “text”, <b/>, “more”, <c/>] e.text = nil e.to_a # => [<a/>, <b/>, “more”, <c/>]

Task: Retrieve the First Text Node¶ ↑

Use method Element#get_text to retrieve the first text node in the element:

d = REXML::Document.new(‘<root><a/>text<b/>more<c/></root>’) e = d.root e.to_a # => [<a/>, “text”, <b/>, “more”, <c/>] e.get_text # => “text”

Task: Retrieve a Specific Text Node¶ ↑

Use method Element#get_text to retrieve the first text node in a specified element:

d = REXML::Document.new “<root>some text this is bold! more text</root>” e = d.root e.get_text(‘//root’) # => “some text ” e.get_text(‘//b’) # => “this is bold!”

Task: Determine Whether the Element has Text Nodes¶ ↑

Use method Element#has_text? to determine whethe the element has text:

e = REXML::Element.new(‘foo’) e.has_text? # => false e.add_text(‘bar’) e.has_text? # => true

Other Children

Task: Get the Child at a Given Index¶ ↑

Use method Element#[] to retrieve the child at a given index:

d = REXML::Document.new ‘><root><a/>text<b/>more<c/></root>’ e = d.root e # => <a/> e # => “text” e # => <b/>

Task: Get All CDATA Children¶ ↑

Use method Element#cdatas to retrieve all CDATA children:

xml_string = <<-EOT <root> <![CDATA]> <![CDATA]> </root> EOT d = REXML::Document.new(xml_string) d.root.cdatas # => [“foo”, “bar”]

Task: Get All Comment Children¶ ↑

Use method Element#comments to retrieve all comment children:

xml_string = <<-EOT <root> <!–foo–> <!–bar–> </root> EOT d = REXML::Document.new(xml_string) d.root.comments.map {|comment| comment.to_s } # => [“foo”, “bar”]

Task: Get All Processing Instruction Children¶ ↑

Use method Element#instructions to retrieve all processing instruction children:

xml_string = <<-EOT <root> <?target0 foo?> <?target1 bar?> </root> EOT d = REXML::Document.new(xml_string) instructions = d.root.instructions.map {|instruction| instruction.to_s } instructions # => [“<?target0 foo?>”, “<?target1 bar?>”]

Task: Get All Text Children¶ ↑

Use method Element#texts to retrieve all text children:

xml_string = ‘<root><a/>text<b/>more<c/></root>’ d = REXML::Document.new(xml_string) d.root.texts # => [“text”, “more”]

Namespaces¶ ↑

Task: Add a Namespace¶ ↑

Use method Element#add_namespace to add a namespace to the element:

e = REXML::Element.new(‘foo’) e.add_namespace(‘bar’) e.namespaces # => {“xmlns”=>“bar”}

Task: Delete the Default Namespace¶ ↑

Use method Element#delete_namespace to remove the default namespace from the element:

d = REXML::Document.new “<a xmlns:foo=‘bar’ xmlns=‘twiddle’/>” d.to_s # => “<a xmlns:foo=‘bar’ xmlns=‘twiddle’/>” d.root.delete_namespace # => <a xmlns:foo=‘bar’/> d.to_s # => “<a xmlns:foo=‘bar’/>”

Task: Delete a Specific Namespace¶ ↑

Use method Element#delete_namespace to remove a specific namespace from the element:

d = REXML::Document.new “<a xmlns:foo=‘bar’ xmlns=‘twiddle’/>” d.to_s # => “<a xmlns:foo=‘bar’ xmlns=‘twiddle’/>” d.root.delete_namespace # => <a xmlns:foo=‘bar’/> d.to_s # => “<a xmlns:foo=‘bar’/>” d.root.delete_namespace(‘foo’) d.to_s # => “<a/>”

Task: Get a Namespace URI¶ ↑

Use method Element#namespace to retrieve a speficic namespace URI for the element:

xml_string = <<-EOT <root> <a xmlns=‘1’ xmlns:y=‘2’> <b/> <c xmlns:z=‘3’/> </a> </root> EOT d = REXML::Document.new(xml_string) b = d.elements b.namespace # => “1” b.namespace(‘y’) # => “2”

Task: Retrieve Namespaces¶ ↑

Use method Element#namespaces to retrieve all namespaces for the element:

xml_string = ‘<a xmlns=“foo” xmlns:x=“bar” xmlns:y=“twee” z=“glorp”/>’ d = REXML::Document.new(xml_string) d.root.attributes.namespaces # => {“xmlns”=>“foo”, “x”=>“bar”, “y”=>“twee”}

Task: Retrieve Namespace Prefixes¶ ↑

Use method Element#prefixes to retrieve all prefixes (namespace names) for the element:

xml_string = <<-EOT <root> <a xmlns:x=‘1’ xmlns:y=‘2’> <b/> <c xmlns:z=‘3’/> </a> </root> EOT d = REXML::Document.new(xml_string, {compress_whitespace: :all}) d.elements.prefixes # => [“x”, “y”] d.elements.prefixes # => [“x”, “y”] d.elements.prefixes # => [“x”, “y”, “z”]

Iteration¶ ↑

Task: Iterate Over Elements¶ ↑

Use method Element#each_element to iterate over element children:

d = REXML::Document.new ‘<a>b<c>b</c><d>d</d><e/></a>’ d.root.each_element {|e| p e }

Output:

<b> … </> <c> … </> <d> … </> <e/>

Task: Iterate Over Elements Having a Specified Attribute¶ ↑

Use method Element#each_element_with_attribute to iterate over element children that have a specified attribute:

d = REXML::Document.new ‘<a><b id=“1”/><c id=“2”/><d id=“1”/><e/></a>’ a = d.root a.each_element_with_attribute(‘id’) {|e| p e }

Output:

<b id=‘1’/> <c id=‘2’/> <d id=‘1’/>

Task: Iterate Over Elements Having a Specified Attribute and Value¶ ↑

Use method Element#each_element_with_attribute to iterate over element children that have a specified attribute and value:

d = REXML::Document.new ‘<a><b id=“1”/><c id=“2”/><d id=“1”/><e/></a>’ a = d.root a.each_element_with_attribute(‘id’, ‘1’) {|e| p e }

Output:

<b id=‘1’/> <d id=‘1’/>

Task: Iterate Over Elements Having Specified Text¶ ↑

Use method Element#each_element_with_text to iterate over element children that have specified text:

Context¶ ↑

#whitespace #ignore_whitespace_nodes #raw

Other Getters¶ ↑

#document #root #root_node #node_type #xpath #inspect