class REXML::Attributes
A class that defines the set of Attributes of an Element and provides operations for accessing elements in that set.
Public Class Methods
Public Instance Methods
Fetches an attribute value. If you want to get the Attribute itself, use #get_attribute()
- name
-
an XPath attribute name. Namespaces are relevant here.
- Returns
-
the String value of the matching attribute, or
nil
if no matching attribute was found. This is the unnormalized value (with entities expanded).
doc = Document.new "<a foo:att='1' bar:att='2' att='<'/>" doc.root.attributes['att'] #-> '<' doc.root.attributes['bar:att'] #-> '2'
# File lib/rexml/element.rb, line 983 def [](name) attr = get_attribute(name) return attr.value unless attr.nil? return nil end
Sets an attribute, overwriting any existing attribute value by the same name. Namespace is significant.
- name
-
the name of the attribute
- value
-
(optional) If supplied, the value of the attribute. If nil, any existing matching attribute is deleted.
- Returns
-
Owning element
doc = Document.new "<a x:foo='1' foo='3'/>" doc.root.attributes['y:foo'] = '2' doc.root.attributes['foo'] = '4' doc.root.attributes['x:foo'] = nil
# File lib/rexml/element.rb, line 1085 def []=( name, value ) if value.nil? # Delete the named attribute attr = get_attribute(name) delete attr return end unless value.kind_of? Attribute if @element.document and @element.document.doctype value = Text::normalize( value, @element.document.doctype ) else value = Text::normalize( value, nil ) end value = Attribute.new(name, value) end value.element = @element old_attr = fetch(value.name, nil) if old_attr.nil? store(value.name, value) elsif old_attr.kind_of? Hash old_attr[value.prefix] = value elsif old_attr.prefix != value.prefix # Check for conflicting namespaces raise ParseException.new( "Namespace conflict in adding attribute \"#{value.name}\": "+ "Prefix \"#{old_attr.prefix}\" = "+ "\"#{@element.namespace(old_attr.prefix)}\" and prefix "+ "\"#{value.prefix}\" = \"#{@element.namespace(value.prefix)}\"") if value.prefix != "xmlns" and old_attr.prefix != "xmlns" and @element.namespace( old_attr.prefix ) == @element.namespace( value.prefix ) store value.name, { old_attr.prefix => old_attr, value.prefix => value } else store value.name, value end return @element end
Adds an attribute, overriding any existing attribute by the same name. Namespaces are significant.
- attribute
-
An Attribute
# File lib/rexml/element.rb, line 1204 def add( attribute ) self[attribute.name] = attribute end
Removes an attribute
- attribute
-
either a String, which is the name of the attribute to remove – namespaces are significant here – or the attribute to remove.
- Returns
-
the owning element
doc = Document.new "<a y:foo='0' x:foo='1' foo='3' z:foo='4'/>" doc.root.attributes.delete 'foo' #-> <a y:foo='0' x:foo='1' z:foo='4'/>" doc.root.attributes.delete 'x:foo' #-> <a y:foo='0' z:foo='4'/>" attr = doc.root.attributes.get_attribute('y:foo') doc.root.attributes.delete attr #-> <a z:foo='4'/>"
# File lib/rexml/element.rb, line 1172 def delete( attribute ) name = nil prefix = nil if attribute.kind_of? Attribute name = attribute.name prefix = attribute.prefix else attribute =~ Namespace::NAMESPLIT prefix, name = $1, $2 prefix = '' unless prefix end old = fetch(name, nil) attr = nil if old.kind_of? Hash # the supplied attribute is one of many attr = old.delete(prefix) if old.size == 1 repl = nil old.each_value{|v| repl = v} store name, repl end elsif old.nil? return @element else # the supplied attribute is a top-level one attr = old super(name) end @element end
Deletes all attributes matching a name. Namespaces are significant.
- name
-
A String; all attributes that match this path will be removed
- Returns
-
an Array of the Attributes that were removed
# File lib/rexml/element.rb, line 1214 def delete_all( name ) rv = [] each_attribute { |attribute| rv << attribute if attribute.expanded_name == name } rv.each{ |attr| attr.remove } return rv end
Iterates over each attribute of an Element, yielding the expanded name and value as a pair of Strings.
doc = Document.new '<a x="1" y="2"/>' doc.root.attributes.each {|name, value| p name+" => "+value }
# File lib/rexml/element.rb, line 1025 def each each_attribute do |attr| yield [attr.expanded_name, attr.value] end end
Iterates over the attributes of an Element. Yields actual Attribute nodes, not String values.
doc = Document.new '<a x="1" y="2"/>' doc.root.attributes.each_attribute {|attr| p attr.expanded_name+" => "+attr.value }
# File lib/rexml/element.rb, line 1010 def each_attribute # :yields: attribute each_value do |val| if val.kind_of? Attribute yield val else val.each_value { |atr| yield atr } end end end
Fetches an attribute
- name
-
the name by which to search for the attribute. Can be a
prefix:name
namespace name. - Returns
-
The first matching attribute, or nil if there was none. This
value is an Attribute node, not the String value of the attribute.
doc = Document.new '<a x:foo="1" foo="2" bar="3"/>' doc.root.attributes.get_attribute("foo").value #-> "2" doc.root.attributes.get_attribute("x:foo").value #-> "1"
# File lib/rexml/element.rb, line 1040 def get_attribute( name ) attr = fetch( name, nil ) if attr.nil? return nil if name.nil? # Look for prefix name =~ Namespace::NAMESPLIT prefix, n = $1, $2 if prefix attr = fetch( n, nil ) # check prefix if attr == nil elsif attr.kind_of? Attribute return attr if prefix == attr.prefix else attr = attr[ prefix ] return attr end end element_document = @element.document if element_document and element_document.doctype expn = @element.expanded_name expn = element_document.doctype.name if expn.size == 0 attr_val = element_document.doctype.attribute_of(expn, name) return Attribute.new( name, attr_val ) if attr_val end return nil end if attr.kind_of? Hash attr = attr[ @element.prefix ] end return attr end
The get_attribute_ns
method retrieves a method by its
namespace and name. Thus it is possible to reliably identify an attribute
even if an XML processor has changed the prefix.
Method contributed by Henrik Martensson
# File lib/rexml/element.rb, line 1228 def get_attribute_ns(namespace, name) result = nil each_attribute() { |attribute| if name == attribute.name && namespace == attribute.namespace() && ( !namespace.empty? || !attribute.fully_expanded_name.index(':') ) # foo will match xmlns:foo, but only if foo isn't also an attribute result = attribute if !result or !namespace.empty? or !attribute.fully_expanded_name.index(':') end } result end
Returns the number of attributes the owning Element contains.
doc = Document "<a x='1' y='2' foo:x='3'/>" doc.root.attributes.length #-> 3
# File lib/rexml/element.rb, line 996 def length c = 0 each_attribute { c+=1 } c end
# File lib/rexml/element.rb, line 1146 def namespaces namespaces = {} each_attribute do |attribute| namespaces[attribute.name] = attribute.value if attribute.prefix == 'xmlns' or attribute.name == 'xmlns' end if @element.document and @element.document.doctype expn = @element.expanded_name expn = @element.document.doctype.name if expn.size == 0 @element.document.doctype.attributes_of(expn).each { |attribute| namespaces[attribute.name] = attribute.value if attribute.prefix == 'xmlns' or attribute.name == 'xmlns' } end namespaces end
Returns an array of Strings containing all of the prefixes declared by this set of # attributes. The array does not include the default namespace declaration, if one exists.
doc = Document.new("<a xmlns='foo' xmlns:x='bar' xmlns:y='twee' "+ "z='glorp' p:k='gru'/>") prefixes = doc.root.attributes.prefixes #-> ['x', 'y']
# File lib/rexml/element.rb, line 1130 def prefixes ns = [] each_attribute do |attribute| ns << attribute.name if attribute.prefix == 'xmlns' end if @element.document and @element.document.doctype expn = @element.expanded_name expn = @element.document.doctype.name if expn.size == 0 @element.document.doctype.attributes_of(expn).each { |attribute| ns << attribute.name if attribute.prefix == 'xmlns' } end ns end
# File lib/rexml/element.rb, line 989 def to_a enum_for(:each_attribute).to_a end