IQueryable conditional include

Question

I have some classes:

public Department {
  public HashSet<Employee> Managers {get; set;}
  public HashSet<Employee> Workers {get; set;}
  public HashSet<Asset> Assets {get; set;}
}

I am using IQueryable to get a deparment collection:

IQueryable<Department> deparments = Context.Department.Where (
dept => dept.CompanyId = id)
.include (dept.Managers.Where (emp => emp.level == Position.Manager) as Managers)
.include (dept.Workers.Where (emp => emp.level == Position.Worker) as Workers)
.include (dept.Asset)

It gave errors when the query is executed. What is the right way to do this? Here is the error msg:

"The Include property lambda expression 'dept => {from Employee emp in dept.Employee where ([emp].Position == Position.Manager) select [emp]}' is invalid. The expression should represent a property access: 't => t.MyProperty'. To target navigations declared on derived types, specify an explicitly typed lambda parameter of the target type, E.g. '(Derived d) => d.MyProperty'.

For more information on including related data, see http://go.microsoft.com/fwlink/?LinkID=746393."

The error is needed so we have an indicator as to what execution is happening. — Kieran Devlin

habib habib · Accepted Answer · 2019-02-27T17:12:14

As your Managers and Workers properties are the direct children of Department class and you don't make reference of Department in Employee class so you can't use Include() for this purpose.

I think you should do this by using subqueries.

var query = (from d in Contex.Department
             where d.CompanyId == id
             select new Department{
                 Managers = d.Managers.where(m => m.level == Position.Manager),
                 Workers = d.Workers.where(w => w.level == Position.Worker),
                 Asset = d.Assets,
             });

Hopefully, it will resolve your problem.

IQueryable conditional include

1 Answers