Entity Framework: Navigation Properties Issue

Question

I am working with Entity Framework code-first, and I have a class Course which has a navigation property Students:

public virtual C         


        

Answer 1

One workaround for this is to flip your query around, though it means avoiding using navigation properties in general. (Actual implementation will vary with your model.)

var allStudents =
   context
   .Students
   .Where(s => s.CourseID == course.ID) // depends on your model
   .Where(s => s.Active)
   .ToList();

I prefer this to using the Entry method, since I use a general interface with my models and I don't want to expose EF6 types.

Another way to avoid exposing EF6 types is to write a method like this:

public IQueryable Nav(
   TParent pParent,
   Expression>> pNavigationExpression
) where TParent : class
where TChild : class =>
   Entry(pParent)
   .Collection(pNavigationExpression)
   .Query();

Used something like this:

var allStudents =
   context
   .Nav(course, c => c.Students)
   .Where(s => s.Active)
   .ToList()