I have a set of product items. Each product item has a multilist field that points to a set of product type items. When on a product page, I want to show a paged list of related items. These should be items that share a product type with the currently selected item. I'm running into some trouble because products can have multiple types. I need to split the type list on the current item and check that against the list of products in an expression. For some reason split and contains are throwing runtime exceptions and I can't really figure out why. I saw some things about the predicate builder being used for dynamic queries and I will try to use that with what I currently have but I'd like to know why this can't be done straight in the where clause.

Another issue I ran into is that the list of ids stored in solr are being stripped of their '{', '}', and '-' characters.