Outputting RSS

Author: Misha v.3 [August 03, 2007]
Version: 1.4
Tags: RSS, XML

More than once or twice I've had to output something as an RSS feed, and at some point I got tired of writing the same, albeit simple, boilerplate xml every time. So I wrote a few classes that hide the intimate details of the RSS format and let you output data into an RSS stream using a handful of simple methods.

# create a Feed object and, if needed, set the <channel/> fields right away.
# you can set any field mentioned in the RSS 2.0 specification.
# for date-type fields you can pass either a date object or a string with a date in sql format.
$oFeed[^FeedRss::create[
	$.title[RSS title]
	$.link[http://$env:SERVER_NAME/]
	$.description[RSS description]

#	by default, docs will output
#	$.docs[http://blogs.law.harvard.edu/tech/rss]

#	by default, generator will output
#	$.generator[^if(def $env:PARSER_VERSION){$env:PARSER_VERSION}{Parser 3}]

#	$.copyright[Copyright (c) Vasya Poupkin]
#	$.webMaster[vasya@poupkin.ru]
#	$.ttl(10)
#	$.image[
#		<title>A pretty short title</title>
#		<url>http://$env:SERVER_NAME/link/to/image.jpg</url>
#		<link>http://$env:SERVER_NAME/</link>
#		<width>100</width>
#		<height>100</height>
#	]
#	and so on
]]

# if you didn't set the <channel/> fields when creating the object, or you want to override them, do so here
^oFeed.set[
	$.title[RSS title ^[updated^]]
]

# add items
# you can set any field mentioned in the RSS 2.0 specification.
# for date-type fields you can pass either a date object or a string with a date in sql format.
# in practice you'll fetch the data from a database/file somehow, and call the addItem method multiple times (e.g. inside a menu).
^oFeed.addItem[
	$.title[Item 1 title]
	$.guid[http://item1-link]
	$.pubDate[^date::create[2007-08-02 22:33:44]]
	$.author[^taint[Name <email@domain.ru>]]
]
^oFeed.addItem[
	$.title[Item 2 title]
	$.guid[http://item2-link]
	$.pubDate[2007-08-01 12:23:34]
	$.description[Item 2 description]
	$.comments[Item 2 comments]
]

# output the RSS stream
# before outputting, the required fields will be checked for being filled in.
# by default, the necessary HTTP headers (last-modified, content-type) will be sent.
^oFeed.print[
	$.sVersion[2.0]

#	you need to specify which Time Zone will be used when outputting date-type fields.
#	per RFC822 it's safe to use the GMT, UTC zones, some USA zones, or a time offset.
#	if the specified zone doesn't match the zone your server runs in,
#	don't forget to manually shift the dates to the right zone when setting the date-type fields on the channel and items.
	$.sTZ[+0300]
#	$.sTZ[GMT]

#	the number of items that will be output. by default, all added items are output.
	$.iItemLimit(10)

#	if specified, items will be sorted by pubDate. by default, they're output in the order they were added.
	$.bOrderItems(true)

#	suppress outputting the XML declaration.
#	$.bOmitXMLDeclaration(true)

#	suppress outputting HTTP headers.
#	$.bOmitHTTPHeaders(true)
]

That's basically it :)

Oh, I forgot to mention that these classes require the dtf.p class to be available, as well as the ArrayList and ArrayListEnumerator classes shamelessly "stolen" from smalex, which have since taken up residence among the useful user-defined operators.

Download:

Feed.zip (15.08.2007  4.5 KB)
Archive of classes for building RSS feeds, with a usage example