Filterable property relations

[mattbrailsford]

I've just been working on the filterable properties feature and I've implemented it for simple types (string, int, dates) but it could be good to support properties that are relations to other entities.

I did mock the following up as an idea

// Generate a filter that is connected to another NPoco entity
collectionConfig.AddFilterableProperty(p => p.UserId)
    .SetRelation("users")
    .SetRelation<User>(u => u.Id,  
        u => u.Name, 
        "icon-users"
        (term) => x.Name.Contains(term) || x.Email.Contains(term))

The first example shows a relation to another collection and so from that we could get the icon, the name and the searchable properties. The later could be a nice way to handle things that aren't really collections (ie, you could create a poco to just fetch Umbraco users in this example). The only problem with the later example is it currently assumes NPoco so it's a question of how to handle these for non NPoco entities? Do we need some kind of "on-the-fly" repository that can do arbitrary queries on entities without needing a full blown collection definition.

Folks would have to swap this out though (unless we implement a factory approach).

Food for thought 🤔