How to refactor parts of an EF select - entity-framework

Question

Let's say I have the following EF code:
context.Employees.Select(e => e
{
FullName = e.FirstName + " " + e.LastName,
StartDate = e.StartDate,
... // Grab other data
};
Now maybe I notice that I construct the full name in multiple places, but would like in centralized. Is it possible to refactor this?
If I make it a method or a Func, I get EF errors, because it can't translate it into SQL.
NOTE: This is a simple example, assume it can get much more complicated with "Select"s, "Where"s, whatever in the assignment, so adding a ToList and then running additional code would be suboptimal and does not fit the definition of refactoring since I would have to change functionality and not just make it more maintainable.

Answer 1

One solution is to use the AsExpandable method from LinqKit:
Expression<Func<Employee,string>> fullName = e => e.FirstName + " " + e.LastName;
context.Employees.AsExpandable().Select(e => e
{
FullName = fullName.Compile().Invoke(e),
StartDate = e.StartDate,
... // Grab other data
};
From the linked article:
Compile is an inbuilt method in the Expression class. It converts the
Expression into a plain Func which
satisfies the compiler. Of course, if this method actually ran, we'd
end up with compiled IL code instead of an expression tree, and LINQ
to SQL or Entity Framework would throw an exception. But here's the
clever part: Compile never actually runs; nor does LINQ to SQL or
Entity Framework ever get to see it. The call to Compile gets stripped
out entirely by a special wrapper that was created by calling
AsExpandable, and substituted for a correct expression tree.
Alternatively, you could look into creating an Model Defined Function with Entity Framework. There's also the Microsoft.Linq.Translations library if you want to define a FullName property on the Employee class itself.

Answer 2

I think the better centralized way to do it in the entity class itself. You can add ReadOnly property to your entity class which should be NotMapped to the database to return required formatted data.
Public class Employee
{
//...
public string fullName{get { return FirstName + " " + LastName;}}
}