I suggested in another blog post (which I'm still writing and will link here when I'm done) that Solr could be used to drive site-wide navigation. Robert Douglas was recently quoted to me (second hand, so I can't verify the source) that the main reason to use Solr is for facets. I would add relevancy scores to that list, but that's for another post. What occurred to me one day was that facets look a lot like “traditional” navigation, only they are smarter (and better looking) than menu items or Views exposed filters.

The other day while hanging out in IRC, I was pinged by katbailey, the Lady of the Lovely Voice (I could listen to her talk for hours) with a question about sorting in Solr when a sort field doesn't contain a value.  In particular, how can you control whether nodes without a value in the sort field show up at the beginning or end of the search results?  In her particular case, there was a Price field that was being sorted on, but not all nodes had a Price value, and the ones without Price were showing up at the beginning of the list.

One of the things I've had to do recently is set up a development server that has multiple sites with Apache Solr so that each site has its own index in Solr.  After searching the internets for information on how to do this, I found two sources that contained part of the process, but not put together in a way that worked for me.  
 

As I mentioned in my previous post on adding a custom sort to Solr, this post is about something that is even simpler; adding a new field to the search results.  In our particular use case, we wanted to add a CCK image field to the results.  To add a slight twist, we needed to add a different image depending on the content type: the user picture for a profile node (created with content_profile module) or a CCK imagefield named field_main_image from the other content types.