I've been struggling for a while now. All I am trying to do is OrderBy a list of records by the Count() of a 3rd child in the relationship tree. I will try and draw the 3 tables involved below, sorry if I don't use the stackoverflow standards:
Websites ----> Roles ----> Permissions
In words, a website can have more than 1 Roles, a role can have more than 1 Permissions. So it's a 1-to-many.
When I try something like:
List<Website> websites = Model.WebsiteOptions.OrderBy( o => o.Roles.OrderBy( r => r.RolePermissions.Count ) ).ToList();
I get an error that's clear enough:
At least one object must implement IComparable.
but I still don't know how I can either way order Websites by the number of Permissions each Role has...What I want is for websites that have Roles with the most Permissions to come first.
Please does anyone know or show me some guidance?
Thanks in advance.
You get that error because in your OrderBy you should specify how to order the collection - meaning supplying an object that implements IComparable.
In your implementation you are actually supplying another collection which is sorted (this is irrelevant though). An IEnumerable<T> doesn't implement IComparable<IEnumerable<T>> but just IComparable<T> - it can compare 2 "simple" items but not two collections. (Will you do it by number of elements?.. biggest element? It is generic so what does biggest even mean.....)
Try something like:
List<Website> websites = Model.WebsiteOptions.OrderBy( o => o.Roles.Max( r => r.RolePermissions.Count ) ).ToList();
This will order your Websites by the option that has the highest RolePermissions count