.net - Return entity that has highest/lowest value in the related entity -

how highest or lowest value related entity? trying use linq/lambda navigation property run nullreferenceexception.

dim e employee = me.employees        .orderby(function(x) x.car.car_age.getvalueordefault(1000))        .first()  if e isnot nothing return e.car.car_age 

with data, case example

employee

id  name   car_id 1   john   1 2   mark   2 3   steve  3 

car

id  car_age 1   15 2   [null] 3   8 4   19 5   3 

employee , car 1-to-1 relationship.

when looking highest value, need employee "john" query. when looking lowest value, need "steve". car_age can null in database.

berfore calling above, entities retrieved database using:

dim query = e in _context.employees.include("car")             select e 

the stack trace suggests have employees without cars. data have 1 shown in post?

what happens if try instead:

dim e employee = me.employees     .where(function(x) x.car isnot nothing)     .orderby(function(x) x.car.car_age.getvalueordefault(1000))     .firstordefault() 

does app still crashes? if not there's problem: employee don't have car.