A referential integrity constraint violation On Update with DbContext

Below is my Model class, my controller action and my view.

When I edit from my view I have got the exception:

A referential integrity constraint violation occurred: The property values that define the referential constraints are not consistent between principal and dependent objects in the relationship.

Code:

public partial class Organization : ILockable, IAuditable, IEntity
{
    /*** Constructor(s) ***/
    public Organization()
    {
 
    }

    public Organization(Party obj)
        : this()
    {
        Party = obj;
    }


    /*** Public Members ***/
    [Key, Display(Name = "Id")]
    public int PartyId { get; set; }

    
    /* IEntity */
    public string Caption { get; set; }

    public string NameInUse { get; set; }

    public string Description { get; set; }

    
    /* IAuditable */
    [NotMapped, ScaffoldColumn(false)]
    public System.DateTimeOffset Created
    {
        get { return Party.Created; }
        set { Party.Created = value; }
    }

    [NotMapped, ScaffoldColumn(false)]
    public string CreatedBy
    {
        get { return Party.CreatedBy; }
        set { Party.CreatedBy = value; }
    }

    [NotMapped, ScaffoldColumn(false)]
    public Nullable<System.DateTimeOffset> LastMod
    {
        get { return Party.LastMod; }
        set { Party.LastMod = value; }
    }

    [NotMapped, ScaffoldColumn(false)]
    public string LastModBy
    {
        get { return Party.LastModBy; }
        set { Party.LastModBy = value; }
    }

    [NotMapped, Display(Name = "Del?")]
    public bool IsSoftDeleted
    {
        get { return Party.IsSoftDeleted; }
        set { Party.IsSoftDeleted = value; }
    }

    [NotMapped, ScaffoldColumn(false)]
    public Nullable<System.DateTimeOffset> SoftDeleted
    {
        get { return Party.SoftDeleted; }
        set { Party.SoftDeleted = value; }
    }

    [NotMapped, ScaffoldColumn(false)]
    public string SoftDeletedBy
    {
        get { return Party.SoftDeletedBy; }
        set { Party.SoftDeletedBy = value; }
    }

    /* ILockable */
    public string GetTableName()
    {
        return "Organization";
    }

    public int GetLockId()
    {
        return this.PartyId;
    }

    /* Navigation Properties */
    /// <summary>
    /// Foreign key to Party: PartyId
    /// Organization is subtype of  Party
    /// </summary>
    public virtual Party Party { get; set; }

}

Controller Edit Action:

    [HttpPost]
    public ActionResult Edit(Organization obj)
    {
        //remove the lock since it is not required for inserts
        if (ModelState.IsValid)
        {
            OrganizationRepo.Update(obj);
            UnitOfWork.Save();
            LockSvc.Unlock(obj);
            return RedirectToAction("List");
        }
        else
        {
            return View();
        }
    }

View:

    @using PartyBiz.Models.Objects
    @using d2Utils.Reflection

    @model IEnumerable<Organization>
    @{
    ViewBag.Title = "Details";
    }

<table>
<tr>
    <th>
        @Html.Raw("Caption")
    </th>
    <th></th>
</tr>
<tr>
<td colspan="4">
        @foreach (var item in Model)
    {   
         <table>
            <tr>
            
      @using (Html.BeginForm("Edit", "Organization", FormMethod.Post))
           {
                 <td >
                    @Html.TextBox("Caption", item.GetValForProp<string>("Caption"), new          { @class = "txt" }) 
                </td>
                <td >
                    @Html.TextBox("NameInUse", item.GetValForProp<string>("NameInUse"), new { @class = "txt" })
                </td>
                <td >
                    @Html.TextBox("Description", item.GetValForProp<string>("Description"), new { @class = "txt" })
                </td>
                <td>
                    <input type="hidden" name="PartyId" value="@item.PartyId"/>
                    <button type="submit">Edit</button>
                </td>
           }
            </tr>
        </table>
    }
</td>
</tr>
</table>

Context method:

    public virtual void Update(T obj)
    {
        IAuditable audit = obj as IAuditable;
        IOverTime overtime = obj as IOverTime;

        // Existing entity
        D2Repository.Updated(ref audit, UserName);
        D2Repository.FromDate(ref overtime);
        

        
        Set.Attach(obj);
        Ctxt.Entry(obj).State = EntityState.Modified;
    }  

I have added

obj.Party.PartyId = obj.PartyId;

in my edit action and it is working now. I still want to know if this is the correct way of doing it?