Cheat sheet

This is a digest of most of the methods documented at nokogiri.org. Reading the source can help, too.

Topics not covered: RelaxNG validation and Builder.

Strings are always stored as UTF-8 internally. Methods that return text values will always return UTF-8 encoded strings. Methods that return XML (like to_xml, to_html and inner_html) will return a string encoded like the source document.

More Resources

• Official Tutorials
• XPath Reference
• XPath Reference 2
• XPath Reference 3
• CSS Selector Reference
• CSS Selector Reference 2
• Mechanize
• Loofah
• Nokogumbo
• HTML/XML parsing tools
• StackOverflow top questions

Creating and working with Documents

Nokogiri::HTML::Document Nokogiri::XML::Document

  doc = Nokogiri(string_or_io) # Nokogiri will try to guess what type of document you are attempting to parse
  doc = Nokogiri::HTML(string_or_io) # [, url, encoding, options, &block]
  doc = Nokogiri::XML(string_or_io) # [, url, encoding, options, &block]
    # set options with block {|config| config.noblanks.noent.noerror.strict }
    # OR with a bitmask {|config| config.options = Nokogiri::XML::ParseOptions::NOBLANKS | Nokogiri::XML::ParseOptions::NOENT}
    # https://nokogiri.org/rdoc/Nokogiri/XML/ParseOptions.html
  # doc = Nokogiri.parse(...)
  # doc = Nokogiri::XML.parse(...) #shortcut to Nokogiri::XML::Document.parse
  # doc = Nokogiri::HTML.parse(...) #shortcut to Nokogiri::HTML::Document.parse
 
  # document namespaces
  doc.collect_namespaces
  doc.remove_namespaces!
  doc.namespaces
   
  # shortcuts for creating new nodes
  doc.create_cdata(string, &block)
  doc.create_comment(string, &block)
  doc.create_element(name, *args, &block) # Create an element
      doc.create_element "div" # <div></div>
      doc.create_element "div", :class => "container" # <div class='container'></div>
      doc.create_element "div", "contents" # <div>contents</div>
      doc.create_element "div", "contents", :class => "container" # <div class='container'>contents</div>
      doc.create_element "div" { |node| node['class'] = "container" } # <div class='container'></div>
  doc.create_entity
  doc.create_text_node(string, &block)
   
  doc.root
  doc.root=node
   
  # A document is a Node, so see working_with_a_node

Working with Fragments

Nokogiri::XML::DocumentFragment Nokogiri::HTML::DocumentFragment

Generally speaking, unless you expect to have a DOCTYPE and a single root node, you don’t have a document, you have a fragment. For HTML, another rule of thumb is that documents have html and body tags, and fragments usually do not.

A fragment is a Node, but is not a Document. If you need to call methods that are only available on Document, like create_element, call fragment.document.create_element.

  fragment = Nokogiri::XML.fragment(string)
  fragment = Nokogiri::HTML.fragment(string, encoding = nil)
  # Note: Searching a fragment relative to the document root with xpath 
  # will probably not return what you expect. You should search relative to 
  # the current context instead. e.g.
  fragment.xpath('//*').size #=> 0
  fragment.xpath('.//*').size #=> 229

Working with a Nokogiri::XML::Node

  node = Nokogiri::XML::Node.new('name', document) # initialize a new node
  node = document.create_element('name') # shortcut
   
  node.document
   
  node.name # alias of node.node_name
  node.name= # alias of node.node_name=
   
  node.read_only?
  node.blank?
   
  # Type of Node
  node.type # alias of node.node_type
  node.cdata? # type == CDATA_SECTION_NODE
  node.comment? # type == COMMENT_NODE
  node.element? # type == ELEMENT_NODE alias node.elem? 
  node.fragment? # type == DOCUMENT_FRAG_NODE (Document fragment node)
  node.html? # type == HTML_DOCUMENT_NODE
  node.text? # type == TEXT_NODE
  node.xml? # type == DOCUMENT_NODE (Document node type)
  # other types not covered by a convenience method
    # ATTRIBUTE_DECL: Attribute declaration type
    # ATTRIBUTE_NODE: Attribute node type
    # DOCB_DOCUMENT_NODE: DOCB document node type
    # DOCUMENT_TYPE_NODE: Document type node type
    # DTD_NODE: DTD node type
    # ELEMENT_DECL: Element declaration type
    # ENTITY_DECL: Entity declaration type
    # ENTITY_NODE: Entity node type
    # ENTITY_REF_NODE: Entity reference node type
    # NAMESPACE_DECL: Namespace declaration type
    # NOTATION_NODE: Notation node type
    # PI_NODE: PI node type
    # XINCLUDE_END: XInclude end type
    # XINCLUDE_START: XInclude start type
   
  # Attributes, like a hash that maps string keys to string values
  node['src'] # aliases: node.get_attribute, node.attr.
  node['src'] = 'value' # alias node.set_attribute
  node.key?('src') # alias node.has_attribute?
  node.keys 
  node.values
  node.delete('src') # alias of node.remove_attribute
  node.each { |attr_name, attr_value| }
  # Node includes Enumerable, which works on these attribute names and values
   
  # Attribute Nodes
  node.attribute('src') # Get the attribute node with name src
    # Returns a Nokogiri::XML::Attr, a subclass of Nokogiri::XML::Node
    # that provides +.content=+ and +.value=+ to modify the attribute value
  node.attribute_nodes # returns an array of this' the Node attributes as Attr objects.
  node.attribute_with_ns('src', 'namespace') # Get the attribute node with name and namespace
  node.attributes # Returns a hash containing the node's attributes. 
    # The key is the attribute name without any namespace, 
    # the value is a Nokogiri::XML::Attr representing the attribute. 
    # If you need to distinguish attributes with the same name, but with different namespaces, use #attribute_nodes instead.
   
   
   
   
  # Traversing / Modifying
  # +node_or_tags+ can be a Node, a DocumentFragment, a NodeSet, or a string containing markup.
  ## Self
  node.traverse { |node| } # yields all children and self to a block, _recursively_.
  node.remove # alias of node.unlink # Unlink this node from its current context.
  node.replace(node_or_tags)
    # Replace this Node with +node_or_tags+.
    # Returns the reparented node (if +node_or_tags+ is a Node), 
    #   or returns a NodeSet (if +node_or_tags+ is a DocumentFragment, NodeSet, or string).
  node.swap(node_or_tags) # like +replace+, but returns self to support chaining
  ## Siblings
  node.next # alias of node.next_sibling # Returns the next sibling node
  node.next=(node_or_tags) # alias of node.add_next_sibling 
    # Inserts node_or_tags after this node (as a sibling).
    # Returns the reparented node (if +node_or_tags+ is a Node)
    #   or returns a NodeSet if (if +node_or_tags is a DocumentFragment, NodeSet, or string.)
  node.after(node_or_tags) # like +next=+, but returns self to suppport chaining
  node.next_element # Returns the next Nokogiri::XML::Element sibling node.
  node.previous # alias of node.previous_sibling # Returns the previous sibling node
  node.previous=(node_or_tags) # alias of node.add_previous_sibling ?
    # Inserts node_or_tags before this node (as a sibling).
    # Returns the reparented node (if +node_or_tags+ is a Node)
    #   or returns a NodeSet (if +node_or_tags+ is a DocumentFragment, NodeSet, or string.)
  node.before(node_or_tags) # just like +previous=+, but returns self to suppport chaining
  node.previous_element # Returns the previous Nokogiri::XML::Element sibling node.
  ## Parent
  node.parent
  node.parent=(node)
  ## Children
  node.child # returns a Node
  node.children # Get the list of children of this node as a NodeSet
  node.children=(node_or_tags)
    # Set the inner html for this Node
    # Returns the reparented node (if +node_or_tags+ is a Node), 
    #   or returns a NodeSet (if +node_or_tags+ is a DocumentFragment, NodeSet, or string).
  node.elements # alias: node.element_children # Get the list of child Elements of this node as a NodeSet.
  node.add_child(node_or_tags)
    # Add +node_or_tags+ as a child of this Node.
    # Returns the reparented node (if +node_or_tags+ is a Node), 
    #   or returns a NodeSet (if +node_or_tags+ is a DocumentFragment, NodeSet, or string.)
  node << node_or_tags # like above, but returns self to support chaining, e.g. root << child1 << child2
  node.first_element_child # Returns the first child node of this node that is an element.
  node.last_element_child # Returns the last child node of this node that is an element.
  ## Content / Children
  node.content # aliases node.text node.inner_text node.to_str
  node.content=(string) # Set the Node's content to a Text node containing +string+. The string gets XML escaped, and will not be interpreted as markup.
  node.inner_html # (*args) children.map { |x| x.to_html(*args) }.join
  node.inner_html=(node_or_tags)
    # Sets the inner html of this Node to +node_or_tags+
    # Returns self.
    # Also see related method +children=+
   
   
   
   
   
  ## Searching below (see Working with a Nodeset below)
  # see docs for namespace bindings, variable bindings, and custom xpath functions via a handler class
  node.search(*paths) # alias: node / path # paths can be XPath or CSS
  node.at(*paths) # alias node % path # Search for the first occurrence of path. Returns nil if nothing is found, otherwise a Node. (like search(path, ns).first)
  node.xpath(*paths) # search for XPath queries
  node.at_xpath(*paths) # like xpath(*paths).first
  node.css(*rules) # search for CSS rules
  node.at_css(*rules) # like css(*rules).first
  node > selector # Search this node's immediate children using a CSS selector
   
   
  # Searching above
  node.ancestors # list of ancestor nodes, closest to furthest, as a NodeSet.
  node.ancestors(selector) # ancestors that match the selector
   
     
  # Where am I?
  node.path # Returns the path associated with this Node
  node.css_path # Get the path to this node as a CSS expression
  node.matches?(selector) # does this node match this selector?
  node.line # line number from input
  node.pointer_id # internal pointer number
   
  # Namespaces
  node.add_namespace(prefix, href) # alias of node.add_namespace_definition
    # Adds a namespace definition with prefix using href value. The result is as
    # if parsed XML for this node had included an attribute
    # ‘xmlns:prefix=value'. A default namespace for this node (“xmlns=”) can be
    # added by passing ‘nil' for prefix. Namespaces added this way will not show
    # up in #attributes, but they will be included as an xmlns attribute when
    # the node is serialized to XML.
  node.default_namespace=(url)
    # Adds a default namespace supplied as a string url href, to self. The
    # consequence is as an xmlns attribute with supplied argument were present
    # in parsed XML. A default namespace set with this method will now show up
    # in #attributes, but when this node is serialized to XML an “xmlns”
    # attribute will appear. See also #namespace and #namespace=
  node.namespace #   returns the default namespace set on this node (as with an “xmlns=” attribute), as a Namespace object.
  node.namespace=(ns)
    # Set the default namespace on this node (as would be defined with an
    # “xmlns=” attribute in XML source), as a Namespace object ns . Note that a
    # Namespace added this way will NOT be serialized as an xmlns attribute for
    # this node. You probably want #default_namespace= instead, or perhaps
    # #add_namespace_definition with a nil prefix argument.
  node.namespace_definitions
    # returns namespaces defined on self element directly, as an array of
    # Namespace objects. Includes both a default namespace (as in“xmlns=”), and
    # prefixed namespaces (as in “xmlns:prefix=”).
  node.namespace_scopes
    # returns namespaces in scope for self – those defined on self element
    # directly or any ancestor node – as an array of Namespace objects. Default
    # namespaces (“xmlns=” style) for self are included in this array; Default
    # namespaces for ancestors, however, are not. See also #namespaces
  node.namespaced_key?(attribute, namespace)
    # Returns true if attribute is set with namespace
  node.namespaces # Returns a Hash of {prefix => value} for all namespaces on this node and its ancestors.
    # This method returns the same namespaces as #namespace_scopes.
    # 
    # Returns namespaces in scope for self – those defined on self element
    # directly or any ancestor node – as a Hash of attribute-name/value pairs.
    # Note that the keys in this hash XML attributes that would be used to
    # define this namespace, such as “xmlns:prefix”, not just the prefix.
    # Default namespace set on self will be included with key “xmlns”. However,
    # default namespaces set on ancestor will NOT be, even if self has no
    # explicit default namespace.
  # see also attribute_with_ns
 
 
  # Rubyisms
  node <=> another_node # Compare two Node objects with respect to their Document. Nodes from different documents cannot be compared.
    # uses xmlXPathCmpNodes "Compare two nodes w.r.t document order"
  node == another_node # compares pointer_id
  node.clone # alias node.dup # Copy this node. An optional depth may be passed in, but it defaults to a deep copy. 0 is a shallow copy, 1 is a deep copy.
 
  # Visitor pattern
  node.accept(visitor) # calls visitor.visit(self)
   
  # Write it out (sorted from most flexible/hardest to use to least flexible/easiest to use)
  node.write_to(io, *options)
    # Write Node to +io+ with +options+. +options+ modify the output of
    # this method.  Valid options are:
    #
    # * +:encoding+ for changing the encoding
    # * +:indent_text+ the indentation text, defaults to one space
    # * +:indent+ the number of +:indent_text+ to use, defaults to 2
    # * +:save_with+ a combination of SaveOptions constants.
      # SaveOptions
        # AS_BUILDER: Save builder created document
        # AS_HTML: Save as HTML
        # AS_XHTML: Save as XHTML
        # AS_XML: Save as XML
        # DEFAULT_HTML: the default for HTML document
        # DEFAULT_XHTML: the default for XHTML document
        # DEFAULT_XML: the default for XML documents
        # FORMAT: Format serialized xml
        # NO_DECLARATION: Do not include declarations
        # NO_EMPTY_TAGS: Do not include empty tags
        # NO_XHTML: Do not save XHTML
    # e.g. node.write_to(io, :encoding => 'UTF-8', :indent => 2)
  node.write_html_to(io, options={}) # uses write_to with :save_with => DEFAULT_HTML option (libxml2.6 does dump_html)
  node.write_xhtml_to(io. options={}) # uses write_to with :save_with => DEFAULT_XHTML option (libxml2.6 does dump_html)
  node.write_xml_to(io, options={}) # uses write_to with :save_with => DEFAULT_XML option
  node.serialize # Serialize Node a string using +options+, provided as a hash or block. Uses write_to (via StringIO)
    # node.serialize(:encoding => 'UTF-8', :save_with => FORMAT | AS_XML)
    # node.serialize(:encoding => 'UTF-8') do |config|
    #   config.format.as_xml
    # end
  node.to_html(options={}) # serializes with :save_with => DEFAULT_HTML option (libxml2.6 does dump_html)
  node.to_xhtml(options={}) # serializes with :save_with => DEFAULT_XHTML option (libxml2.6 does dump_html)
  node.to_xml(options={}) # serializes with :save_with => DEFAULT_XML option
  node.to_s # document.xml? ? to_xml : to_html
 
  node.inspect
  node.pretty_print(pp) # to enhance pp
 
  # Utility
  node.encode_special_chars(str) # Encodes special characters :P
  node.fragment(tags) # Create a DocumentFragment containing tags that is relative to this context node.
  node.parse(string_or_io, options={})
    # Parse +string_or_io+ as a document fragment within the context of
    # *this* node.  Returns a XML::NodeSet containing the nodes parsed from
    # +string_or_io+.
   
  # External subsets, like DTD declarations
  node.create_external_subset(name, external_id, system_id)
  node.create_internal_subset(name, external_id, system_id)
  node.external_subset
  node.internal_subset
   
  # Other:
  node.description # Fetch the Nokogiri::HTML::ElementDescription for this node. Returns nil on XML documents and on unknown tags.
    # e.g. if node is an <img> tag: Nokogiri::HTML::ElementDescription['img']  Nokogiri::HTML::ElementDescription: img embedded image >
  node.decorate! # Decorate this node with the decorators set up in this node's Document. Used internally to provide Slop support and Hpricot compatibility via Nokogiri::Hpricot
  node.do_xinclude # options as a block or hash
    # Do xinclude substitution on the subtree below node. If given a block, a
    # Nokogiri::XML::ParseOptions object initialized from +options+, will be
    # passed to it, allowing more convenient modification of the parser options.
 

Working with a Nokogiri::XML::NodeSet

  nodes = Nokogiri::XML::NodeSet.new(document, list=[])
   
  # Set operations
  nodes | other_nodeset # UNION, i.e. merging the sets, returning a new set
  nodes + other_nodeset # UNION, i.e. merging the sets, returning a new set
  nodes & other_nodeset # INTERSECTION # i.e. return a new NodeSet with the common nodes only
  nodes - other_nodeset # DIFFERENCE Returns a new NodeSet containing the nodes in this NodeSet that aren't in other_nodeset
  nodes.include?(node)
  nodes.empty?
  nodes.length # alias nodes.size
  nodes.delete(node) # Delete node from the Nodeset, if it is a member. Returns the deleted node if found, otherwise returns nil.
 
  # List operations (includes Enumerable)
  nodes.each { |node| }
  nodes.first
  nodes.last
  nodes.reverse # Returns a new NodeSet containing all the nodes in the NodeSet in reverse order
  nodes.index(node) # returns the numeric index or nil
  nodes[3] # element at index 3
  nodes[3,4] # return a NodeSet of size 4, starting at index 3
  nodes[3..6] # or return a NodeSet using a range of indexes
  # alias nodes.slice
  nodes.pop # Removes the last element from set and returns it, or nil if the set is empty
  nodes.push(node) # alias nodes << node # Append node to the NodeSet.
  nodes.shift # Returns the first element of the NodeSet and removes it. Returns nil if the set is empty.
  nodes.filter(expr) # Filter this list for nodes that match an XPATH or CSS query
    # find_all { |node| node.matches?(expr) }
   
  nodes.children # Returns a new NodeSet containing all the children of all the nodes in the NodeSet
   
  # Content
  nodes.inner_html(*args) # Get the inner html of all contained Node objects
  nodes.inner_text # alias nodes.text
   
  # Convenience modifiers
  nodes.remove # alias of nodes.unlink # Unlink this NodeSet and all Node objects it contains from their current context.
  nodes.wrap("<div class='container'></div>") # wrap new xml around EACH NODE in a Nodeset
  nodes.before(datum) # Insert datum before the first Node in this NodeSet # e.g. first.before(datum)
  nodes.after(datum) # Insert datum after the last Node in this NodeSet # e.g. last.after(datum)
  nodes.attr(key, value) # set the attribute key to value on all Node objects in the NodeSet
  nodes.attr(key) { |node| 'value' } # set the attribute key to the result of the block on all Node objects in the NodeSet
    # alias nodes.attribute, nodes.set
  nodes.remove_attr(name) # removes the attribute from all nodes in the nodeset
  nodes.add_class(name) # Append the class attribute name to all Node objects in the NodeSet.
  nodes.remove_class(name = nil) # if nil, removes the class attrinute from all nodes in the nodeset
   
  # Searching
  nodes.search(*paths) # alias nodes / path
  nodes.at(*paths) # alias nodes % path
  nodes.xpath(*paths)
  nodes.at_xpath(*paths)
  nodes.css(*rules)
  nodes.at_css(*rules)
  nodes > selector # Search this NodeSet's nodes' immediate children using CSS selector
   
  # Writing out
  nodes.to_a # alias nodes.to_ary # Return this list as an Array
  nodes.to_html(*args)
  nodes.to_s
  nodes.to_xhtml(*args)
  nodes.to_xml(*args)
   
  # Rubyisms
  nodes == nodes # Two NodeSets are equal if the contain the same number of elements and if each element is equal to the corresponding element in the other NodeSet
  nodes.dup # Duplicate this node set
  nodes.inspect

Miscellany

  nc = Nokogiri::HTML::NamedCharacters # a Nokogiri::HTML::EntityLookup
  nc[key] # like nc.get(key).try(:value) # e.g. nc['gt'] (62) or nc['rsquo'] (8217)
  nc.get(key) # returns an Nokogiri::HTML::EntityDescription
    # e.g. nc.get('rsquo') #=>  #<struct Nokogiri::HTML::EntityDescription value=8217, name="rsquo", description="right single quotation mark, U+2019 ISOnum">
   
  # Adding a Processing Instruction (like <?xml-stylesheet?>)
  # Nokogiri::XML::ProcessingInstruction https://nokogiri.org/tutorials/modifying_an_html_xml_document.html
  pi = Nokogiri::XML::ProcessingInstruction.new(doc, "xml-stylesheet",'type="text/xsl" href="foo.xsl"')
  doc.root.add_previous_sibling(pi)

Reader parsers

Reader parsers can be used to parse very large XML documents quickly without the need to load the entire document into memory or write a SAX document parser. The reader makes each node in the XML document available exactly once, only moving forward, like a cursor.

  reader = Nokogiri::XML::Reader(string_or_io)
    # attrs
    # .encoding
    # .errors
    # .source
 
  # Reading
  reader.each {|node|  } # node and reader are the same object. shortcut for while(node = self.read) yield(node); end;
  reader.read # Move the Reader forward through the XML document.
 
  node.name
  node.local_name
 
  # Attributes
  node.attribute('src')
  node.attribute_at(1)
  node.attribute_count
  node.attribute_nodes
  node.attributes
  node.attributes?
 
  # Content
  node.empty_element?
  node.self_closing?
  node.value # Get the text value of the node if present as a utf-8 encoded string. Does NOT advance the reader.
  node.value? # Does this node have a text value?
  node.inner_xml # Read the contents of the current node, including child nodes and markup into a utf-8 encoded string. Does NOT advance the reader
  node.outer_xml # Does NOT advance the reader
 
  node.base_uri # Get the xml:base of the node
  node.default? # Was an attribute generated from the default value in the DTD or schema?
  node.depth
 
  # Namespaces and the rest
  node.namespace_uri # Get the URI defining the namespace associated with the node
  node.namespaces # Get a hash of namespaces for this Node
  node.prefix # Get the shorthand reference to the namespace associated with the node.
  node.xml_version # Get the XML version of the document being read
  node.lang # Get the xml:lang scope within which the node resides.
  node.node_type
    # one of 
    # TYPE_ATTRIBUTE
    # TYPE_CDATA
    # TYPE_COMMENT
    # TYPE_DOCUMENT
    # TYPE_DOCUMENT_FRAGMENT
    # TYPE_DOCUMENT_TYPE
    # TYPE_ELEMENT
    # TYPE_END_ELEMENT
    # TYPE_END_ENTITY
    # TYPE_ENTITY
    # TYPE_ENTITY_REFERENCE
    # TYPE_NONE
    # TYPE_NOTATION
    # TYPE_PROCESSING_INSTRUCTION
    # TYPE_SIGNIFICANT_WHITESPACE
    # TYPE_TEXT
    # TYPE_WHITESPACE
    # TYPE_XML_DECLARATION
  node.state # Get the state of the reader

XSD Validation

XSD XSD::XMLParser XSD::XMLParser::Nokogiri

  xsd = Nokogiri::XML::Schema(string_or_io_to_schema_file)
  doc = Nokogiri::XML(File.read(PO_XML_FILE))
   
  xsd.valid?(doc) # => true/false
    
  xsd.validate(doc) # returns an an array of SyntaxError s
  xsd.validate(doc).each do |syntax_error|
    syntax_error.error?
    syntax_error.fatal?
    syntax_error.none?
    syntax_error.to_s
    syntax_error.warning?
     
    # undocumented attributes
    syntax_error.code R
    syntax_error.column R
    syntax_error.domain R
    syntax_error.file R
    syntax_error.int1 R
    syntax_error.level R
    syntax_error.line R
    syntax_error.str1 R
    syntax_error.str2 R
    syntax_error.str3 R
  end
   
   
  # https://nokogiri.org/rdoc/Nokogiri/XML/Schema.html
  # https://nokogiri.org/rdoc/Nokogiri/XML/AttributeDecl.html
  # https://nokogiri.org/rdoc/Nokogiri/XML/DTD.html
  # https://nokogiri.org/rdoc/Nokogiri/XML/ElementDecl.html
  # https://nokogiri.org/rdoc/Nokogiri/XML/ElementContent.html
  # https://nokogiri.org/rdoc/Nokogiri/XML/EntityDecl.html
  # https://nokogiri.org/rdoc/Nokogiri/XML/EntityReference.html
   
  doc.validate # validate it against its DTD, if it has one

CSS Parsing

Nokogiri::CSS Nokogiri::CSS::Node Nokogiri::CSS::Parser Nokogiri::CSS::SyntaxError Nokogiri::CSS::Tokenizer Nokogiri::CSS::Tokenizer::ScanError

  # https://nokogiri.org/rdoc/Nokogiri/CSS.html
  Nokogiri::CSS.parse('selector') # => returns an AST
  Nokogiri::CSS.xpath_for('selector', options={})
   
  # https://nokogiri.org/rdoc/Nokogiri/CSS/Node.html
    # attr: type, value
    #methods
    # accept(visitor)
    # find_by_type
    # new
    # preprocess!
    # to_a
    # to_type
    # to_xpath
  # https://nokogiri.org/rdoc/Nokogiri/CSS/Parser.html # a Racc generated Parser

XSLT Transformation

Nokogiri::XSLT Nokogiri::XSLT::Stylesheet

  doc   = Nokogiri::XML(File.read('some_file.xml'))
  xslt  = Nokogiri::XSLT(File.read('some_transformer.xslt'))
  puts xslt.transform(doc) # [, xslt_parameters]
  #   xslt.serialize(doc) # to am xml string
  #   xslt.apply_to(doc, params=[]) # equivalent to xslt.serialize(xslt.transform(doc, params))

SAX Parsing

Event-driving XML parsing appropriate for reading very large XML files without reading the entire document into memory. The best documentation is in this file.

# Document template
# Define any or all of these methods to get their notifications:
# Your document doesn't have to subclass Nokogiri::XML::SAX::Document, 
# doing so just saves you from having to define all the sax methods, 
# rather than the few you need.
class MyDocument < Nokogiri::XML::SAX::Document
  def xmldecl(version, encoding, standalone)
  end
  def start_document
  end
  def end_document
  end
  def start_element(name, attrs = [])
  end
  def end_element(name)
  end
  def start_element_namespace(name, attrs = [], prefix = nil, uri = nil, ns = [])
  end
  def end_element_namespace(name, prefix = nil, uri = nil)
  end
  def characters(string)
  end
  def comment(string)
  end
  def warning(string)
  end
  def error(string)
  end
  def cdata_block(string)
  end
end
 
# Standard Parser
parser = Nokogiri::XML::SAX::Parser.new(MyDocument.new) # [, encoding = 'UTF-8]
# A block can be passed to the parse methods to get the ParserContext before parsing, but you probably don't need that
parser.parse(string_or_io)
parser.parse_io(io) # [, encoding = "ASCII"]
parser.parse_file(filename)
parser.parse_memory(string)
 
# If you want HTML correction features, instantiate this parser instead
parser = Nokogiri::HTML::SAX::Parser.new(MyDoc.new)

(If you're a weirdo,) You can stream the XML manually using Nokogiri::SAX::PushParser The best documentation is this file.

Slop decorator (Don’t use this)

The ::Slop decorator implements method_missing such that methods may be used instead of CSS or XPath. See the bottom of this page Nokogiri.Slop Nokogiri::XML::Document#slop! Nokogiri::Decorators::Slop

doc = Nokogiri::Slop(string_or_io)
doc = Nokogiri(string_or_io).slop!
doc = Nokogiri::HTML(string_or_io).slop!
doc = Nokogiri::XML(string_or_io).slop!
 
doc = Nokogiri::Slop(<<-eohtml)
  <html>
    <body>
      <p>first</p>
      <p>second</p>
    </body>
  </html>
eohtml
assert_equal('second', doc.html.body.p[1].text)
 
 
doc = Nokogiri::Slop <<-EOXML
<employees>
  <employee status="active">
    <fullname>Dean Martin</fullname>
  </employee>
  <employee status="inactive">
    <fullname>Jerry Lewis</fullname>
  </employee>
</employees>
EOXML
 
# navigate!
doc.employees.employee.last.fullname.content # => "Jerry Lewis"
 
# access node attributes!
doc.employees.employee.first["status"] # => "active"
 
# use some xpath!
doc.employees.employee("[@status='active']").fullname.content # => "Dean Martin"
doc.employees.employee(:xpath => "@status='active'").fullname.content # => "Dean Martin"
 
# use some css!
doc.employees.employee("[status='active']").fullname.content # => "Dean Martin"
doc.employees.employee(:css => "[status='active']").fullname.content # => "Dean Martin"