Loading data from one table via another - entity-framework

Question

I am trying to load each staff members holiday record but I am unable to populate holiday records.
Here is the code from my controller:
public class HomeController : Controller
{
private HRModel.db_HRSystemModel db = new HRModel.db_HRSystemModel();
public IActionResult Index()
{
var staff = (from s in db.Hrstaffpersonaldetails
where s.Firstname == "Ian"
select s).ToList();
return View(staff);
}
}
and here is the code from my view:
<div>
<h4>Staff</h4>
<hr />
#foreach (var s in Model)
{
<dl class="dl-horizontal">
<dt>
First Name:
</dt>
<dd>
#s.Firstname
</dd>
<dt>
Surname:
</dt>
<dd>
#s.Surname
</dd>
<dt>
Username:
</dt>
<dd>
#s.Username
</dd>
#foreach (var hr in s.Hrstaffholidayrecords)
{
<dt>
date:
</dt>
<dd>
#hr.Startdate
</dd>
}
</dl>
}
</div>
When I currently run what I have (on .NET Core 1.1), holiday records returns 0 records from the database. I'm not really sure if I'm missing something or I'm doing it wrong.
Thanks,
Ian

Answer 1

Change the controller code to this should work.
public class HomeController : Controller
{
private HRModel.db_HRSystemModel db = new HRModel.db_HRSystemModel();
public IActionResult Index()
{
var staff = db.Hrstaffpersonaldetails
.Include(s => s.Hrstaffholidayrecords)
.Where(s => s.Firstname == "Ian")
.ToList();
return View(staff);
}
}
This is called eager loading. Read more at https://learn.microsoft.com/en-us/ef/core/querying/related-data
Besides, the db context object is supposed to be injected into controller using DI. Read more at https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/dependency-injection

Answer 2

looks like lazy loading, but not sure, not that strong at this) you should read smth about fluent API