Component linking and magical parameters in Tridion's XSLT component templates
I was recently asked a question about XSLT templating in Tridion. The question was about how you create component linking code from within your XSLT component template. The tricky part is that you need a publication ID and a component template ID. My solution involved getting these in the page template and passing them in to the XSLT as parameters. OK - job done - it's just coding from there eh? Well yes - but it didn't stop being interesting at that point, because my questioner in the meantime had come up with his own solution based on some sample code that he'd found on the Tridion forum. He hadn't needed to add the parameters himself, because Tridion adds some parameters for you as if by magic.
It turns out that if you include any of the following three global parameters at the top of your XSLT, Tridion will add the corresponding DOMs as parameters as if by magic.
<xsl:param name="tcm:Page"/> <xsl:param name="tcm:Publication"/> <xsl:param name="tcm:ComponentTemplate"/>
This is very cool, and saves you the effort of coding it, but I don't know whether it's a supported feature. I suppose it should be, because it's really just the standard behaviour for a component template translated to XSLT. I just can't find it anywhere in the documentation.
There is a gotcha, mind you! Although the parameters are declared in the "tcm:" namespace, which resolves to "http://www.tridion.com/ContentManager/5.0", don't be tempted to use a prefix other than "tcm:" for this namespace. If you do, you'll find that there's something broken; the parameters don't seem to be added automatically. (Tested on R51SP4) Still - as it's an undocumented, and perhaps unsupported feature, we can't really complain.
It would make a good enhancement request though. Perhaps Tridion can be persuaded to document this and support it. In the meantime, perhaps it's better to be on the safe side and explicitly add the parameters you need to the Component Presentation from the Page Template.