how and where to connect viewmodel to dbcontext - asp.net

Question

I inherited a mvc app. This app uses entity framework with database first. It was made with no viewmodels and viewbags everywhere for the dropdowns and error messages. Now I am tasked with making many changes to it because you can not validate the related properties that are not in the main class among other things.
I am trying to create a viewmodel so I can display only necessary data, validate it and not be linked directly to the model. So far I get null for all my fields on a form using the viewmodel I created. I have tried to use automapper but get a mapping error: "Missing type map configuration or unsupported mapping"
Here is part of the controller:
public ActionResult ChangeOwner(int id = 0)
{
var combine = new combineValidationAssetViewModel();
Mapper.CreateMap<ToolingAppEntities1, combineValidationAssetViewModel>();
Mapper.CreateMap<combineValidationAssetViewModel, ToolingAppEntities1>();
Asset asset = db.Assets.Find(id);
Mapper.Map(combine, asset, typeof(combineValidationAssetViewModel), typeof(Asset));
.....
return View(combine);
}
Here is part of the view model:
public class combineValidationAssetViewModel
{
public Asset Assets { get; set; }
public Transaction Transactions { get; set; }
public LocationType LocationTypes { get; set; }
public ToolType ToolTypes { get; set; }
public OwnerType OwnerTypes { get; set; }
public int AssetId { get; set; }
public int fkToolTypeId { get; set; }
[Required]
[Display(Name = "Owner")]
public int fkOwnerId { get; set; }
[Required]
[Display(Name = "Location")]
public int fkLocationId { get; set; }
public int LocationTypeId { get; set; }
public int OwnerTypeId { get; set; }
Here is part of the view:
#model ToolApp.ViewModels.combineValidationAssetViewModel
.....
#using (Html.BeginForm()) {
#Html.ValidationSummary(true)
<fieldset>
<legend>Asset</legend>
#Html.HiddenFor(model => model.AssetId)
#Html.HiddenFor(model => model.CreatedByUser)
#Html.HiddenFor(model => model.CreateDate)
#Html.HiddenFor(model => model.SerialNumber)
#Html.HiddenFor(model => model.LocationTypeId)
<div class="editor-label">
#Html.LabelFor(model =>model.SerialNumber)
</div>
<div class="editor-field">
#Html.DisplayFor(model => model.SerialNumber)
</div>
<div class="editor-label">
#Html.LabelFor(model => model.fkToolTypeId, "Tool Name")
</div>
<div class="editor-field">
#Html.DisplayFor(model => model.Description)
</div>
<div class="editor-label">
#Html.LabelFor(model => model.fkOwnerId, "New Owner")
</div>
<div class="editor-field">
#Html.DropDownListFor(model => model.fkOwnerId, new SelectList(ViewBag.fkOwnerId, "Value", "Text"), new{style="width:320px;height:25px;"})
#Html.ValidationMessageFor(model => model.fkOwnerId),
The form displays but it is null (no values in any of the fields displayed. I would like to map it manually so I understand it. Have tried the automapper but it's not working yet. I have tried some ideas from here and other websites but same result. I don't completely understand the linq to ef yet so my problem may lie there also.
This main controller has 10 different action results on it and is filled with data calls and viewbags. I'm looking for advice on the direction I should go. I need to get the thing working but also want to make changes to it that will move it in the direction of a viable mvc app. Main issue at the moment is how to connect the viewmodel with the dbcontext. I found the context at the top of the controller like this:
{ private ToolingAppEntities1 db = new ToolingAppEntities1();
followed by many includes...
any suggestions would be appreciated

Answer 1

You map into the wrong direction:
Mapper.Map(combine, asset,
typeof(combineValidationAssetViewModel), typeof(Asset));
This maps the empty combine object to asset. You should reverse it, and use a strong-typed (generic) overload:
var combine = Mapper.Map<combineValidationAssetViewModel>(asset);