EF core NullReferenceException accessing related entity

Question

How do you update a subtable value with Lambda EF core.

var UpdatePercentage = _context.TaskOverview.Single(c => c.Id == 100);
UpdatePercentage.Completedpercentage = 30;
UpdatePercentage.TaskSubInfo.Content1 = "Some value";

await _context.SaveChangesAsync();

I get NullReferenceException error

NullReferenceException: Object reference not set to an instance of an object.

on which of your three lines do you get your exception: is your _context null? or is UpdatePercentage.CompletedPercentage null? Or perhaps UpdatePercentage.TaskSubInfo is null? — Harald Coppoolse, Dec 05 '16 at 11:10
Possible duplicate of [What is a NullReferenceException, and how do I fix it?](http://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — kiziu, Dec 05 '16 at 11:12

score 0 · Answer 1 · answered Dec 05 '16 at 11:09

0

You can use Include

var UpdatePercentage = _context.TaskOverview.Include("TaskSubInfo").Single(c => c.Id == 100);

answered Dec 05 '16 at 11:09

Eldaniz Ismayilov

856
6
18

score 0 · Accepted Answer · answered Dec 05 '16 at 11:34

I guess you are getting the NullReferenceException on the related Entity TaskSubInfo.

EntityFramework doesnt load related Entity by default but you have to do it

var UpdatePercentage = _context.TaskOverview
                            .Include(to => to.TaskSubInfo)
                            .Single(c => c.Id == 100);

UpdatePercentage?.Completedpercentage = 30;
UpdatePercentage?.TaskSubInfo.Content1 = "Some value";

await _context.SaveChangesAsync();

EF core NullReferenceException accessing related entity

2 Answers2