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 { xmm.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 { 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>
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, 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(:ident=>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. out must respond to the << operator. The default 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=><b>OBSOLETE</em>: | 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. |
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# File vendor/rails/activesupport/lib/active_support/vendor/builder/xmlmarkup.rb, line 184 184: def initialize(options={}) 185: indent = options[:indent] || 0 186: margin = options[:margin] || 0 187: super(indent, margin) 188: @target = options[:target] || "" 189: 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]]>
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# File vendor/rails/activesupport/lib/active_support/vendor/builder/xmlmarkup.rb, line 258 258: def cdata!(text) 259: _ensure_no_block block_given? 260: _special("<![CDATA[", "]]>", text, nil) 261: end
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# File vendor/rails/activesupport/lib/active_support/vendor/builder/xmlmarkup.rb, line 196 196: def comment!(comment_text) 197: _ensure_no_block block_given? 198: _special("<!-- ", " -->", comment_text, nil) 199: end
Insert an XML declaration into the XML markup.
For example:
xml.declare! :ELEMENT, :blah, "yada" # => <!ELEMENT blah "yada">
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# File vendor/rails/activesupport/lib/active_support/vendor/builder/xmlmarkup.rb, line 207 207: def declare!(inst, *args, &block) 208: _indent 209: @target << "<!#{inst}" 210: args.each do |arg| 211: case arg 212: when String 213: @target << %{ "#{arg}"} 214: when Symbol 215: @target << " #{arg}" 216: end 217: end 218: if block_given? 219: @target << " [" 220: _newline 221: _nested_structures(block) 222: @target << "]" 223: end 224: @target << ">" 225: _newline 226: 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"?>
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# File vendor/rails/activesupport/lib/active_support/vendor/builder/xmlmarkup.rb, line 237 237: def instruct!(directive_tag=:xml, attrs={}) 238: _ensure_no_block block_given? 239: if directive_tag == :xml 240: a = { :version=>"1.0", :encoding=>"UTF-8" } 241: attrs = a.merge attrs 242: end 243: _special( 244: "<?#{directive_tag}", 245: "?>", 246: nil, 247: attrs, 248: [:version, :encoding, :standalone]) 249: end
Return the target of the builder.
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# File vendor/rails/activesupport/lib/active_support/vendor/builder/xmlmarkup.rb, line 192 192: def target! 193: @target 194: end