I'm looking for a little input on how others have approached this problem I had on a recent build (one I think is somewhat common).

For my project I had seven seperate taxonomy categories that applied to multiple types of content, all with their own unique field values. Some taxonomys affected multiple page types, others a single type. for example:

Taxonomy 1: applies to regular content page type.

Select one 
(a,b,c)

Taxonomy 2: applies to regular content page type and article page type.

Select Many

(a,b,c,d,e,f,g)

Taxonomy 3: applies to article page type and product page type.

Select One:

(a,b,c,d)

What I ended up doing is creating an interface for each taxonomy type, and a selection factory with the choices for each taxonomy. I'd then apply the taxonomies to each page type using those interfaces. The interface was very simple, just a string field for the taxonomy field. I would then apply SelectOne or SelectMany attribute. Basically I'd run a scheduled job that would crawl the site and load all of this information into a simple cache for querying, basically just the name of the item, its content ID and what it was tagged with. Heres a quick example of some code, obfuscated with (Taxonomy Name) wherever a specific taxonomy name was used:

Heres an interface example:

public interface I(TaxonomyName)Taxonomy : ITaxonomyBase
{
string (TaxonomyName)Tags { get; set; }
}

heres an example of the field added to a content type:

[Display(Name = "(Taxonomy Name) Taxonomy",
Description = "(Taxonomy Name)Taxonomy tagging system, you may select as many as you want.",
GroupName = Global.GroupNames.Taxonomy,
Order = 10)]
[SelectMany(SelectionFactoryType = typeof((Taxonomy Name)SelectionFactory))]
public virtual string (Taxonomy Name)Tags { get; set; }

and lastly one of the selection factories:

public class (TaxonomyName)SelectionFactory : ISelectionFactory
{
public IEnumerable GetSelections(ExtendedMetadata metadata)
{
return (TaxonomyName)Selections.TaxonomyOptions;
}
}

public static class (TaxonomyName)Selections
{
public static ISelectItem[] TaxonomyOptions
{
get
{
return new ISelectItem[] 
{
new SelectItem() { Text = "example data", Value = "example data" } ,

new SelectItem() { Text = "example data", Value = "example data" } ,

new SelectItem() { Text = "example data", Value = "example data" } ,

new SelectItem() { Text = "example data", Value = "example data" } 



};

}
}
}