Is it possible to store the result of an expression in a property? about nein-linq HOT 4 CLOSED

Yeah, if you remove the protected setter of your property (nein-linq "injects" read-only properties only), that should do it.

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I'm having trouble getting it to work with this code (TestInjection always returns 0):
Using NeinLinq.EntityFrameworkCore v5.0.1.

Class:

public class MyFoo
{
	[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
	public int Id { get; set; }
	public string Name { get; set; }

	[NotMapped]
	[InjectLambda]
	public long TestInjection { get; }

	public static Expression<Func<MyFoo, long>> TestInjectionExpr => myFoo => myFoo.Id + 1;
}

Test:

[Fact]
public void TestFooInjection()
{
	UsingDbContext(db =>
	{
		var foo = new MyFoo()
		{
			Name = "Heythere",
		};

		db.MyFoos.Add(foo);
		db.SaveChanges();

		var fooResult = db.MyFoos.ToInjectable().First();
		fooResult.TestInjection.ShouldBeGreaterThan(0);

	});
}

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Also I tried using ToEntityInjectable() and it's still returning 0 for the TestInjection property.

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Note to myself: don't answer any questions before second coffee...

NeinLinq intercepts during projection. Thus, without any LINQ query can't happen a thing. In order to use lampda injection you'll need some kind of projection to view models or the like.

I'll play with your use case next week or so, but I don't think there can be a LINQ based solution for this. Maybe implementing an EF Core based interceptor might help here?

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