class Builder::XmlMarkup
Create XML markup easily. All (well, almost all) methods sent to an XmlMarkup
object will be translated to the equivalent XML markup. Any method with a block will be treated as an XML markup tag with nested markup in the block.
Examples will demonstrate this easier than words. In the following, xm
is an XmlMarkup
object.
xm.em("emphasized") # => <em>emphasized</em> xm.em { xm.b("emp & bold") } # => <em><b>emph & bold</b></em> xm.a("A Link", "href"=>"http://onestepback.org") # => <a href="http://onestepback.org">A Link</a> xm.div { xm.br } # => <div><br/></div> xm.target("name"=>"compile", "option"=>"fast") # => <target option="fast" name="compile"\> # NOTE: order of attributes is not specified. xm.instruct! # <?xml version="1.0" encoding="UTF-8"?> xm.html { # <html> xm.head { # <head> xm.title("History") # <title>History</title> } # </head> xm.body { # <body> xm.comment! "HI" # <!-- HI --> xm.h1("Header") # <h1>Header</h1> xm.p("paragraph") # <p>paragraph</p> } # </body> } # </html>
Notes:¶ ↑
-
The order that attributes are inserted in markup tags is undefined.
-
Sometimes you wish to insert text without enclosing tags. Use the
text!
method to accomplish this.Example:
xm.div { # <div> xm.text! "line"; xm.br # line<br/> xm.text! "another line"; xmbr # another line<br/> } # </div>
-
The special XML characters <, >, and & are converted to <, > and & automatically. Use the
<<
operation to insert text without modification. -
Sometimes tags use special characters not allowed in ruby identifiers. Use the
tag!
method to handle these cases.Example:
xml.tag!("SOAP:Envelope") { ... }
will produce …
<SOAP:Envelope> ... </SOAP:Envelope>"
tag!
will also take text and attribute arguments (after the tag name) like normal markup methods. (But see the next bullet item for a better way to handle XML namespaces). -
Direct support for XML namespaces is now available. If the first argument to a tag call is a symbol, it will be joined to the tag to produce a namespace:tag combination. It is easier to show this than describe it.
xml.SOAP :Envelope do ... end
Just put a space before the colon in a namespace to produce the right form for builder (e.g. “
SOAP:Envelope
” => “xml.SOAP :Envelope
”) -
XmlMarkup
builds the markup in any object (called a target) that accepts the<<
method. If no target is given, thenXmlMarkup
defaults to a string target.Examples:
xm = Builder::XmlMarkup.new result = xm.title("yada") # result is a string containing the markup. buffer = "" xm = Builder::XmlMarkup.new(buffer) # The markup is appended to buffer (using <<) xm = Builder::XmlMarkup.new(STDOUT) # The markup is written to STDOUT (using <<) xm = Builder::XmlMarkup.new x2 = Builder::XmlMarkup.new(:target=>xm) # Markup written to +x2+ will be send to +xm+.
-
Indentation is enabled by providing the number of spaces to indent for each level as a second argument to XmlBuilder.new. Initial indentation may be specified using a third parameter.
Example:
xm = Builder.new(:indent=>2) # xm will produce nicely formatted and indented XML. xm = Builder.new(:indent=>2, :margin=>4) # xm will produce nicely formatted and indented XML with 2 # spaces per indent and an over all indentation level of 4. builder = Builder::XmlMarkup.new(:target=>$stdout, :indent=>2) builder.name { |b| b.first("Jim"); b.last("Weirich) } # prints: # <name> # <first>Jim</first> # <last>Weirich</last> # </name>
-
The instance_eval implementation which forces self to refer to the message receiver as self is now obsolete. We now use normal block calls to execute the markup block. This means that all markup methods must now be explicitly send to the xml builder. For instance, instead of
xml.div { strong("text") }
you need to write:
xml.div { xml.strong("text") }
Although more verbose, the subtle change in semantics within the block was found to be prone to error. To make this change a little less cumbersome, the markup block now gets the markup object sent as an argument, allowing you to use a shorter alias within the block.
For example:
xml_builder = Builder::XmlMarkup.new xml_builder.div { |xml| xml.stong("text") }
Public Class Methods
Create an XML markup builder. Parameters are specified by an option hash.
- :target => target_object
-
Object
receiving the markup.target_object
must respond to the<<(a_string)
operator and return itself. The default target is a plain string target. - :indent => indentation
-
Number of spaces used for indentation. The default is no indentation and no line breaks.
- :margin => initial_indentation_level
-
Amount of initial indentation (specified in levels, not spaces).
- :quote => :single
-
Use single quotes for attributes rather than double quotes.
- :escape_attrs => OBSOLETE
-
The :escape_attrs option is no longer supported by builder (and will be quietly ignored).
String
attribute values are now automatically escaped. If you need unescaped attribute values (perhaps you are using entities in the attribute values), then give the value as aSymbol
. This allows much finer control over escaping attribute values.
Builder::XmlBase::new
# File lib/builder/xmlmarkup.rb 190 def initialize(options={}) 191 indent = options[:indent] || 0 192 margin = options[:margin] || 0 193 @quote = (options[:quote] == :single) ? "'" : '"' 194 @explicit_nil_handling = options[:explicit_nil_handling] 195 super(indent, margin) 196 @target = options[:target] || "".dup 197 end
Public Instance Methods
Insert a CDATA section into the XML markup.
For example:
xml.cdata!("text to be included in cdata") #=> <![CDATA[text to be included in cdata]]>
# File lib/builder/xmlmarkup.rb 270 def cdata!(text) 271 _ensure_no_block ::Kernel::block_given? 272 _special("<![CDATA[", "]]>", text.gsub(']]>', ']]]]><![CDATA[>'), nil) 273 end
# File lib/builder/xmlmarkup.rb 275 def cdata_value!(open, text) 276 _ensure_no_block ::Kernel::block_given? 277 _special("<#{open}>", "</#{open}>", "<![CDATA[#{text.gsub(']]>', ']]]]><![CDATA[>')}]]>", nil) 278 end
# File lib/builder/xmlmarkup.rb 204 def comment!(comment_text) 205 _ensure_no_block ::Kernel::block_given? 206 _special("<!-- ", " -->", comment_text, nil) 207 end
Insert an XML declaration into the XML markup.
For example:
xml.declare! :ELEMENT, :blah, "yada" # => <!ELEMENT blah "yada">
# File lib/builder/xmlmarkup.rb 215 def declare!(inst, *args, &block) 216 _indent 217 @target << "<!#{inst}" 218 args.each do |arg| 219 case arg 220 when ::String 221 @target << %{ "#{arg}"} # " WART 222 when ::Symbol 223 @target << " #{arg}" 224 end 225 end 226 if ::Kernel::block_given? 227 @target << " [" 228 _newline 229 _nested_structures(block) 230 @target << "]" 231 end 232 @target << ">" 233 _newline 234 end
Insert a processing instruction into the XML markup. E.g.
For example:
xml.instruct! #=> <?xml version="1.0" encoding="UTF-8"?> xml.instruct! :aaa, :bbb=>"ccc" #=> <?aaa bbb="ccc"?>
Note: If the encoding is setup to “UTF-8” and the value of $KCODE is “UTF8”, then builder will emit UTF-8 encoded strings rather than the entity encoding normally used.
# File lib/builder/xmlmarkup.rb 248 def instruct!(directive_tag=:xml, attrs={}) 249 _ensure_no_block ::Kernel::block_given? 250 if directive_tag == :xml 251 a = { :version=>"1.0", :encoding=>"UTF-8" } 252 attrs = a.merge attrs 253 @encoding = attrs[:encoding].downcase 254 end 255 _special( 256 "<?#{directive_tag}", 257 "?>", 258 nil, 259 attrs, 260 [:version, :encoding, :standalone]) 261 end
Return the target of the builder.
# File lib/builder/xmlmarkup.rb 200 def target! 201 @target 202 end
Private Instance Methods
# File lib/builder/xmlmarkup.rb 326 def _attr_value(value) 327 case value 328 when ::Symbol 329 value.to_s 330 else 331 _escape_attribute(value.to_s) 332 end 333 end
Insert an ending tag.
# File lib/builder/xmlmarkup.rb 310 def _end_tag(sym) 311 @target << "</#{sym}>" 312 end
# File lib/builder/xmlmarkup.rb 335 def _ensure_no_block(got_block) 336 if got_block 337 ::Kernel::raise IllegalBlockError.new( 338 "Blocks are not allowed on XML instructions" 339 ) 340 end 341 end
Insert the attributes (given in the hash).
# File lib/builder/xmlmarkup.rb 315 def _insert_attributes(attrs, order=[]) 316 return if attrs.nil? 317 order.each do |k| 318 v = attrs[k] 319 @target << %{ #{k}=#{@quote}#{_attr_value(v)}#{@quote}} if v 320 end 321 attrs.each do |k, v| 322 @target << %{ #{k}=#{@quote}#{_attr_value(v)}#{@quote}} unless order.member?(k) # " WART 323 end 324 end
Insert special instruction.
# File lib/builder/xmlmarkup.rb 291 def _special(open, close, data=nil, attrs=nil, order=[]) 292 _indent 293 @target << open 294 @target << data if data 295 _insert_attributes(attrs, order) if attrs 296 @target << close 297 _newline 298 end
Start an XML tag. If end_too
is true, then the start tag is also the end tag (e.g. <br/>
# File lib/builder/xmlmarkup.rb 302 def _start_tag(sym, attrs, end_too=false) 303 @target << "<#{sym}" 304 _insert_attributes(attrs) 305 @target << "/" if end_too 306 @target << ">" 307 end
Insert text directly in to the builder's target.
# File lib/builder/xmlmarkup.rb 286 def _text(text) 287 @target << text 288 end