Entity Framework - Selective Condition on Included Navigation Property

Question

Assume I have these simplified EF generated entities...

public class PurchaseOrder
{
     public int POID {get;set;}
     public int OrderID         


        

Answer 1

You could use the IQueryable-Extensions here:

https://github.com/thiscode/DynamicSelectExtensions

The Extension builds dynamically an anonymous type. This will be used for projection as described by @Ladislav-Mrnka.

Then you can do this:

var query = query.SelectIncluding( new List>>>(){

//Example how to retrieve only the newest history entry
x => x.HistoryEntries.OrderByDescending(x => x.Timestamp).Take(1),

//Example how to order related entities
x => x.OtherEntities.OrderBy(y => y.Something).ThenBy(y => y.SomeOtherThing),

//Example how to retrieve entities one level deeper
x => x.CollectionWithRelations.Select(x => x.EntityCollectionOnSecondLevel),

//Of course you can order or subquery the deeper level
//Here you should use SelectMany, to flatten the query
x => x.CollectionWithRelations.SelectMany(x => x.EntityCollectionOnSecondLevel.OrderBy(y => y.Something).ThenBy(y => y.SomeOtherThing)),

});