entity framework does not load navigation property after adding object
c# entity-framework entity-framework-6
Question
I have MVC project and EF6 model.
LazyLoading is enabled. In controller I have the following action
public ActionResult AddStage(int projectId, int employeeId)
{
using(var context = new TestProjectEntities())
{
var project = context.Projects.Find(projectId);
if (project != null)
{
var stage = new Stage() {EmployeeID = employeeId, StageType = 1};
project.Stages.Add(stage);
context.Stages.Add(stage);
context.SaveChanges();
}
ListEmployees(project);
}
return Redirect("Index");
}
private void ListEmployees(Project project)
{
var names = new List<string>();
foreach(var stage in project.Stages)
{
if (stage.Employee != null)
{
names.Add(stage.Employee.Name);
}
}
}
But in ListEmployees method stage.Employee == null in foreach statement. Why?
And if i call AddStage for second time then stage.Employee != null in ListEmployee
Accepted Answer
That's because you're simply setting the foreign-key property (Stage.EmployeeID) without setting the navigation-property (Stage.Employee).
Usually, after calling SaveChanges(), EF would update the navigation property as well. But, since the Stage object is created manually by you it's not tracked (using a DynamicProxy) and you'll have to explicitly fix-up the relationship:
context.Entry(stage).Reference(c => c.Employee).Load();
Another approach would be to fetch the Employee and use it instead of setting the foreign-key property:
var employee = context.Employees.Find(employeeId);
var stage = new Stage() { Employee = employee, StageType = 1};
See MSDN
Popular Answer
new Stage()
Don't do this with EF objects. You won't get the correct proxy object that can lazy load navigation properties. You need to use something like dbContext.Set<Stage>().Create()
Related Questions
Licensed under: CC-BY-SA with attribution
Not affiliated with Stack Overflow