Encrypted Id is not retaining back in controller - asp.net-mvc-4

Question

I am encrypting id to hide the raw id in query string and passing it to the controller. But the Id is not retaining back in the postback to the controller.
for eg
/Vendor/EditVendor/mELirpUhRYksFj7k8-XBcQ%3d%3d
DecryptLong() method will decrypt the above id string mELirpUhRYksFj7k8-XBcQ%3d%3d to 1
controller
public ActionResult EditVendor(string id)
{
var vendor = _vendorService.GetVendorById(id.DecryptLong());
return View(vendor);
}
[HttpPost]
public ActionResult EditVendor(Vendor vendor)
{
if (ModelState.IsValid)
{
vendor.Id -- it is always zero and not retaining back
_vendorService.EditVendor(vendor);
}
return View(vendor);
}
In view
#model Eclatech.KidsHub.Objects.Vendor
#{
ViewBag.Title = "EditVendor";
Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>Edit Vendor</h2>
#using(Html.BeginForm("EditVendor","Vendor",FormMethod.Post, new Dictionary<string, object>
{
{"class","form-horizontal"},
{"role","form"}
}))
{
<div class="form-group">
#Html.LabelFor(m => m.VendorName, new Dictionary<string, object>
{
{"class","col-sm-2 control-label"}
})
<div class="col-sm-10">
#Html.TextBoxFor(m => m.VendorName,new Dictionary<string, object>
{
{"class","form-control"}
})
</div>
</div>
#Html.HiddenFor(m => m.Id)
<input type="submit" class="btn btn-primary btn-default" value="Save" />
}
Model
public class Vendor : AuditableEntity<long>
{
public string VendorName { get; set; }
public virtual ICollection<Product> Products { get; set; }
}
public abstract class AuditableEntity<T> : Entity<T>, IAuditableEntity
{
[ScaffoldColumn(false)]
public DateTime CreatedDate { get; set; }
[MaxLength(256)]
[ScaffoldColumn(false)]
public string CreatedBy { get; set; }
[ScaffoldColumn(false)]
public DateTime UpdatedDate { get; set; }
[MaxLength(256)]
[ScaffoldColumn(false)]
public string UpdatedBy { get; set; }
}
public abstract class Entity<T> : BaseEntity, IEntity<T>
{
private static long _rowNumber;
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public virtual T Id { get; set; }
[NotMapped]
public virtual long RowNumber
{
get { return ++_rowNumber; }
}
}

Answer 1

The problem is that your parameter name for the EditVendor method is named id and you are returning a model that also has a property named id. When you call the EditVendor method, the value of the parameter is added to ModelState which overrides the value of property Vendor.Id. If you inspect the html generated by #Html.HiddenFor(m => m.Id) you will see that the value of the input is mELirpUhRYksFj7k8-XBcQ%3d%3d, not the value returned by DecryptLong(). When this posts back, it cannot be bound to type int so Id has its default value of zero.
You can test this by adding ModelState.Clear(); before calling GetVendorById(). This will clear the value of Id and the hidden inputs value will now be 1. To solve the problem, change the name of the parameter, for example
public ActionResult EditVendor(string vendorID)
{
var vendor = _vendorService.GetVendorById(vendorID.DecryptLong());
return View(vendor);
}