Hierarchical data representation using entity framework in MVC

Question

Hey i am trying to work with entity framework using in DB first mode. I have a hierarchy of Enitties that are stored in one table called "DomainEntities".

When i generated a schema using the entity framework i got the correct mappongs that look like this.

Now i wonder what is the way i should perform insert using this model. if i want to insert a new entry with a certain parent do i need to do all this:

[HttpPost]
public ActionResult Create(DomainEntity i_EntityToCreate, int ParentEntityID)
{
    using (var db = new CamelotShiftManagementEntities())
    {
        var parentEntity = db.DomainEntities.Find(ParentEntityID);
        i_EntityToCreate.ParentEntity = parentEntity;
        i_EntityToCreate.EntityTypeID = 1;

        db.DomainEntities.Add(i_EntityToCreate);

        db.SaveChanges();
    }
    return RedirectToAction("Index");
}

is this correct or is there another design i should follow to represent a hierarchy of entities using entity framework ?

I guess there must be "ParentEntityID" field in "DomainEntity"? — Kundan Singh Chouhan
– Kundan Singh Chouhan, Commented Sep 1, 2012 at 11:59
There is but the asp.net entity framework converted it to the association of parentEntity and children .. i have no access to the int value of the parent entity id that i would set as a nullable int — Mortalus
– Mortalus, Commented Sep 1, 2012 at 12:17
There is an option available when you import the table in EF. "Include foreign key columns in the model". Ensure that it must be selected in order to see this field. — Kundan Singh Chouhan
– Kundan Singh Chouhan, Commented Sep 1, 2012 at 12:20
Where can i find this options ? is it while i create the EDMX scheme ? — Mortalus
– Mortalus, Commented Sep 1, 2012 at 12:33

Kundan Singh Chouhan · Accepted Answer · 2012-09-02 04:52:53Z

1

There is no need to find the ParentEntity you can use the ParentEntityID directly with DomainEntity object like this, To get the foreign key column in the model, tick the option of "Include foreign key columns in the model" when importing tables in to EDMX.

After that use below code :

[HttpPost]
public ActionResult Create(DomainEntity i_EntityToCreate, int? ParentEntityID)
{
  using (var db = new CamelotShiftManagementEntities())
  {
    i_EntityToCreate.ParentEntityId = ParentEntityID;
    i_EntityToCreate.EntityTypeID = 1;

    db.DomainEntities.Add(i_EntityToCreate);

    db.SaveChanges();
  }

  return RedirectToAction("Index");

}

If the ParentEntityID is not null than remove the ? mark so that it become not nullable type.

answered Sep 2, 2012 at 4:52

Kundan Singh Chouhan

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