Getting model to viewmodel easily

Question

I have a view-model like this:

public class U1MyProfile1ViewModel : U1Profile
{
    public List<SelectListItem> CountryList { get; set; }
}

Thinking that I want the model accessible to the view, plus a some extra fields that aren't really part of the model, such as a drop down list of countries.

Then in the controller I try to "pass the model over to the view-model"

        var myProfile = await _mainDbContext.U1Profiles
            .AsNoTracking()
            .FirstOrDefaultAsync(i => i.SiteUserId == mySiteUserId);

        U1MyProfile1ViewModel myProfileViewModel = (U1MyProfile1ViewModel)myProfile;

this compiles, but I get a runtime error of:

InvalidCastException: Unable to cast object of type 'WebApp.Models.U1Profile' to type 'WebApp.ViewModels.U1MyProfile1ViewModel'.

Any ideas on how to do this easily?
Something simpler than assigning the model to the view-model field by field.

If you do not want to initialize and map `U1Profile` to `U1MyProfile1ViewModel`, then you can consider using [AutoMapper](https://automapper.org/) - but you would still need to populate the SelectList — , Oct 29 '18 at 04:38
Why you inherits viewmodel to model? View model is always work freely without depending on anything. — Kiran Joshi, Oct 29 '18 at 06:16

Kiran Joshi · Accepted Answer · 2018-10-30T07:08:01.050

1

Set your View model like follow:

View modal

public class U1MyProfile1ViewModel
{
    public List<SelectListItem> CountryList { get; set; }
    public U1Profile U1Profile{get;set;}
    public string othervariable{get;set;}
}

Controller

var myProfile = await _mainDbContext.U1Profiles
            .AsNoTracking()
            .FirstOrDefaultAsync(i => i.SiteUserId == mySiteUserId);

        U1MyProfile1ViewModel myProfileViewModel = new U1MyProfile1ViewModel;
       U1MyProfile1ViewModel.U1Profile=myProfile;
       U1MyProfile1ViewModel.CountryList=yourcountrylist;

And finally just passed your viewmodal to View and you get your result.

For better understanding just see below link:
Link1
Link2

edited Oct 30 '18 at 07:08

answered Oct 29 '18 at 06:29

Kiran Joshi

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View model should not contain data models when editing data - it defeats the whole point of using view model (separation of concerns, protection against over-posting attacks, protection against under-posting attacks etc) – Oct 29 '18 at 07:42
@StephenMuecke make sense. Thanks. How we deal with this ? – Kiran Joshi Oct 30 '18 at 04:49

Getting model to viewmodel easily

1 Answers1