实体框架ICollection列出

Question

I am trying to do something like this:

 List<Department> t = db.Employees
        .Where(e => e.CompanyId.Equals(12345))
        .Where(e => e.Departments.Any(d => d.IsActive.Equals(true)))
        .Select(e => e.Departments);

But it gives me an error telling me that can't implicitly convert from IQueryable<ICollection<Department>> to List<Department> .

My Linq is a bit rusty. What is the right way to bring this down to the List<Department>

Answer 1

You have a queryable collection of a collection of departments (note the plural e.Departments ). As a result, you can use .SelectMany() to flatten your collection and then resolve the IQueryable with .ToList() .

List<Department> t = db.Employees
    .Where(e => e.CompanyId.Equals(12345))
    .Where(e => e.Departments.Any(d => d.IsActive.Equals(true)))
    .SelectMany(e => e.Departments).ToList();