[[!template id=plugin name=aggregate author="[[Joey]]"]]
[[!tag type/useful]]

This plugin allows content from other feeds to be aggregated into the wiki.
Aggregate a feed as follows:

	\[[!aggregate name="example blog" dir="example"
	feedurl="http://example.com/index.rss"
	url="http://example.com/" updateinterval="15"]]

That example aggregates posts from the specified RSS feed, updating no
more frequently than once every 15 minutes, and puts a page per post under
the example/ directory in the wiki.

You can then use ikiwiki's [[ikiwiki/blog]] support to create a blog of one or
more aggregated feeds. For example:

	\[[!inline pages="internal(example/*)"]]

## setup

New users of aggregate should enable the `aggregateinternal => 1` option in the
.setup file. If you don't do so, you will need to enable the [[html]] plugin
as well as aggregate itself, since feed entries will be stored as HTML.

The [[meta]] and [[tag]] plugins are also recommended. The
[[htmltidy]] plugin is suggested, since feeds can easily contain html
problems, some of which tidy can fix.

You will need to run ikiwiki periodically from a cron job, passing it the
--aggregate parameter, to make it check for new posts. Here's an example
crontab entry:

	*/15 * * * * ikiwiki --setup my.wiki --aggregate --refresh

Alternatively, you can allow `ikiwiki.cgi` to trigger the aggregation. You
should only need this if for some reason you cannot use cron, and instead
want to use a service such as [WebCron](http://webcron.org). To enable
this, turn on `aggregate_webtrigger` in your setup file. The url to
visit is `http://whatever/ikiwiki.cgi?do=aggregate_webtrigger`. Anyone
can visit the url to trigger an aggregation run, but it will only check
each feed if its `updateinterval` has passed.

## usage

Here are descriptions of all the supported parameters to the `aggregate`
directive:

* `name` - A name for the feed. Each feed must have a unique name.
  Required.
* `url` - The url to the web page for the feed that's being aggregated.
  Required.
* `dir` - The directory in the wiki where pages should be saved. Optional,
  if not specified, the directory is based on the name of the feed.
* `feedurl` - The url to the feed. Optional, if it's not specified ikiwiki
  will look for feeds on the `url`. RSS and atom feeds are supported.
* `updateinterval` - How often to check for new posts, in minutes. Default
  is 15 minutes.
* `expireage` - Expire old items from this feed if they are older than
  a specified number of days. Default is to never expire on age.
* `expirecount` - Expire old items from this feed if there are more than
  the specified number total. Oldest items will be expired first. Default
  is to never expire on count.
* `tag` - A tag to tag each post from the feed with. A good tag to use is
  the name of the feed. Can be repeated multiple times. The [[tag]] plugin
  must be enabled for this to work.
* `template` - Template to use for creating the aggregated pages. Defaults to
  aggregatepost.

Note that even if you are using subversion or another revision control
system, pages created by aggregation will *not* be checked into revision
control.

## internal pages and `aggregateinternal`

This plugin creates a page for each aggregated item. 

If the `aggregateinternal` option is enabled in the setup file (which is
recommended), aggregated pages are stored in the source directory with a
"._aggregated" extension. These pages cannot be edited by web users, and
do not generate first-class wiki pages. They can still be inlined into a
blog, but you have to use `internal` in [[PageSpecs|IkiWiki/PageSpec]],
like `internal(blog/*)`.

For backward compatibility, the default is that these pages have the
".html" extension, and are first-class wiki pages -- each one generates
a separate HTML page in the output, and they can even be edited.

That turns out to not be ideal for aggregated content, because publishing
files for each of those pages is a waste of disk space and CPU, and you
probably don't want to allow them to be edited. So, there is an alternative
method that can be used (and is recommended), turned on by the
`aggregateinternal` option in the setup file.

If you are already using aggregate and want to enable `aggregateinternal`,
you should follow this process:

1. Update all [[PageSpecs|ikiwiki/PageSpec]] that refer to the aggregated
   pages -- such as those in inlines. Put "internal()" around globs 
   in those PageSpecs. For example, if the PageSpec was `foo/*`, it should
   be changed to `internal(foo/*)`. This has to be done because internal
   pages are not matched by regular globs.
2. Turn on `aggregateinternal` in the setup file.
3. Use [[ikiwiki-transition]] to rename all existing aggregated `.html`
   files in the srcdir. The command to run is
   `ikiwiki-transition aggregateinternal $setupfile`,
4. Refresh the wiki. (`ikiwiki -setup your.setup -refresh`)