CrispCreations

As well as looking at robots.txt, search engines like Googlebot look for meta tags to determine what to do when they arrive at a page. With use of the Themes module meta block, and some custom variables, it's possible to add this meta information dynamically, and prevent duplicate content appearing in listings.

What's it for?

Why might you want to do that? Well, let's say you have an article called 'SEO',  with an aid of 9, in the articles module belonging to a howto pubtype with a ptid of 2.

Depending on your url setup, that one article can be accessed by any or all of the following urls

?module=articles&aid=9

?module=articles&ptid=2&aid=9

/articles/9

/articles/howto/9

/articles/howto/SEO

/articles/SEO

/howto/SEO

/howto/SEO/9

/howto/9

/howto/SEO/02-02-08 12:00

That's 10 possible combinations which will return the content for a single page, you can see how easy it is to get duplicates. You can double that number by including index.php in the urls too.

Now, with a little template magic, we can decide if we're on the page we want the search engine to index, and have it ignore the others.

How to do it

First of all, we need the url for the page we want indexed. We can find this out by having Xaraya tell us what it should be, based on current settings. Taking the example above, we'd place this code in our articles user-display.xt template

<xar:set name="$urltoindex"> #xarModURL('articles', 'user', 'display', array('ptid' => $pubtypeid, 'aid' => $aid))# </xar:set>

All we've done there is get the URL xaraya would normally use to display the current page.

Now we get the current url we're actually at.

<xar:set name="$currenturl"> #xarServerGetCurrentURL()# </xar:set>

Now we have that information, we can use it to decide what we want search bots to do.

<xar:if condition="$urltoindex ne $currenturl"> <xar:set name="cachethis"> #xarVarSetCached('Blocks.mycache', 'noindex', true)# </xar:set> </xar:if>

Now we just need to add a little code to the meta block template, over-ride themes/xartemplates/blocks/meta.xd in your theme and add the following code.

<xar:if condition="xarVarIsCached('Blocks.mycache', 'noindex')"> <xar:set name="$noindex"> #xarVarGetCached('Blocks.mycache', 'noindex')#"> </xar:set> </xar:else /> <xar:set name="$noindex">'0'</xar:set> </xar:if> <xar:if condition="$noindex"> <meta name="META/ROBOTS" content="NOINDEX" /> </xar:if>

With that done, you can use the same compare to determine if other pages on your site should be indexed or not, all you need to know is the real display page you want indexed, and add the necessary check to your templates.