Date: 2004-10-22T17:23:31
Editor: RossGardler <[EMAIL PROTECTED]>
Wiki: Cocoon Wiki
Page: ResourceExistsAction
URL: http://wiki.apache.org/cocoon/ResourceExistsAction
no comment
Change Log:
------------------------------------------------------------------------------
@@ -1,57 +1,59 @@
=== This action is being slowly phased out in favor of the
ResourceExistsSelector ===
+(See ResourceExistsSelector)
+
This action allows you to process different pipelines based on whether a
resource exists. This is useful when you have this sort of a pipeline:
-{{{
-<map:match pattern="foo/*/">
- <map:generate src="docs/{1}.xml"/>
- <map:transform src="xslt/foo2html.xsl"/>
- <map:serialize type="xhtml"/>
-</map:match>
+{{{
+<map:match pattern="foo/*/">
+ <map:generate src="docs/{1}.xml"/>
+ <map:transform src="xslt/foo2html.xsl"/>
+ <map:serialize type="xhtml"/>
+</map:match>
}}}
Althought the wildcards in the sitemap are extremely powerful, you will run
into problems when someone requests a URL which will substitute to a file that
does not exist:
-{{{
-GET /foo/nowhere/ HTTP/1.1
+{{{
+GET /foo/nowhere/ HTTP/1.1
}}}
Obviously, the sitemap will look for {{{docs/nowhere.xml}}}, it won't be
found, and you'll end up with an ugly {{{ResourceNotFoundException}}}.
If you only care about reporting that a resource does not exist, you have this
option:
-{{{
-<map:pipeline>
-<map:handle-errors type="404">
- <map:transform src="xslt/error2html.xsl"/>
- <map:serialize type="html"/>
-</map:handle-errors>
-</map:pipeline>
+{{{
+<map:pipeline>
+<map:handle-errors type="404">
+ <map:transform src="xslt/error2html.xsl"/>
+ <map:serialize type="html"/>
+</map:handle-errors>
+</map:pipeline>
}}}
However, if you wish to "fall-back" to a different pipeline if a file doesn't
exist, you may use the !ResourceExistsAction:
(inspired from the
[http://marc.theaimsgroup.com/?l=xml-cocoon-users&m=102188726924367&w=2 mailing
list])
-{{{
-<map:match pattern="foo/*/">
-
- <!-- check to see if the requested resource is actually a valid source
document -->
-
- <map:act type="resource-exists">
- <map:parameter name="url" value="context://documents/{1}.xml"/>
- <map:generate src="context://documents/{../1}.xml" type="file"/>
- <map:transform src="xslt/doc2html.xsl"/>
- <map:serialize type="xhtml"/>
- </map:act>
-
- <!-- otherwise, we can do this stuff -->
-
- <map:generate src="docs/system/notfound.xml"/>
- <map:transform src="xslt/notfound2html.xsl/>
- <map:serialize type="xhtml"/>
-
-</map:match>
+{{{
+<map:match pattern="foo/*/">
+
+ <!-- check to see if the requested resource is actually a valid source
document -->
+
+ <map:act type="resource-exists">
+ <map:parameter name="url" value="context://documents/{1}.xml"/>
+ <map:generate src="context://documents/{../1}.xml" type="file"/>
+ <map:transform src="xslt/doc2html.xsl"/>
+ <map:serialize type="xhtml"/>
+ </map:act>
+
+ <!-- otherwise, we can do this stuff -->
+
+ <map:generate src="docs/system/notfound.xml"/>
+ <map:transform src="xslt/notfound2html.xsl/>
+ <map:serialize type="xhtml"/>
+
+</map:match>
}}}
'''note''':
