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.h1("Header") # <h1>Header</h1> xm.p("paragraph") # <p>paragraph</p> } # </body> } # </html>
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, then XmlMarkup 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") }
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). |
: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 a Symbol. This allows much finer control over escaping attribute values. |
# File lib/builder/xmlmarkup.rb, line 185 185: def initialize(options={}) 186: indent = options[:indent] || 0 187: margin = options[:margin] || 0 188: super(indent, margin) 189: @target = options[:target] || "" 190: end
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, line 263 263: def cdata!(text) 264: _ensure_no_block ::Kernel::block_given? 265: _special("<![CDATA[", "]]>", text, nil) 266: end
Insert an XML declaration into the XML markup.
For example:
xml.declare! :ELEMENT, :blah, "yada" # => <!ELEMENT blah "yada">
# File lib/builder/xmlmarkup.rb, line 208 208: def declare!(inst, *args, &block) 209: _indent 210: @target << "<!#{inst}" 211: args.each do |arg| 212: case arg 213: when ::String 214: @target << %{ "#{arg}"} # " WART 215: when ::Symbol 216: @target << " #{arg}" 217: end 218: end 219: if ::Kernel::block_given? 220: @target << " [" 221: _newline 222: _nested_structures(block) 223: @target << "]" 224: end 225: @target << ">" 226: _newline 227: 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, line 241 241: def instruct!(directive_tag=:xml, attrs={}) 242: _ensure_no_block ::Kernel::block_given? 243: if directive_tag == :xml 244: a = { :version=>"1.0", :encoding=>"UTF-8" } 245: attrs = a.merge attrs 246: @encoding = attrs[:encoding].downcase 247: end 248: _special( 249: "<?#{directive_tag}", 250: "?>", 251: nil, 252: attrs, 253: [:version, :encoding, :standalone]) 254: end
# File lib/builder/xmlmarkup.rb, line 314 314: def _attr_value(value) 315: case value 316: when ::Symbol 317: value.to_s 318: else 319: _escape_quote(value.to_s) 320: end 321: end
Insert an ending tag.
# File lib/builder/xmlmarkup.rb, line 298 298: def _end_tag(sym) 299: @target << "</#{sym}>" 300: end
# File lib/builder/xmlmarkup.rb, line 323 323: def _ensure_no_block(got_block) 324: if got_block 325: ::Kernel::raise IllegalBlockError.new( 326: "Blocks are not allowed on XML instructions" 327: ) 328: end 329: end
Insert the attributes (given in the hash).
# File lib/builder/xmlmarkup.rb, line 303 303: def _insert_attributes(attrs, order=[]) 304: return if attrs.nil? 305: order.each do |k| 306: v = attrs[k] 307: @target << %{ #{k}="#{_attr_value(v)}"} if v # " WART 308: end 309: attrs.each do |k, v| 310: @target << %{ #{k}="#{_attr_value(v)}"} unless order.member?(k) # " WART 311: end 312: end
Insert special instruction.
# File lib/builder/xmlmarkup.rb, line 279 279: def _special(open, close, data=nil, attrs=nil, order=[]) 280: _indent 281: @target << open 282: @target << data if data 283: _insert_attributes(attrs, order) if attrs 284: @target << close 285: _newline 286: end
Start an XML tag. If end_too is true, then the start tag is also
the end tag (e.g.
# File lib/builder/xmlmarkup.rb, line 290 290: def _start_tag(sym, attrs, end_too=false) 291: @target << "<#{sym}" 292: _insert_attributes(attrs) 293: @target << "/" if end_too 294: @target << ">" 295: end
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