访问相关实体的EF核心NullReferenceException

Question

如何使用Lambda EF核心更新子表值。

calculate

我收到NullReferenceException错误

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

await _context.SaveChangesAsync();

Answer 1

我猜你在相关NullReferenceException TaskSubInfo上获得了Entity。

EntityFramework默认不加载相关的Entity，但 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();