Do you use viewModel instead of ViewData?

ASP.NET CORE MVC provides several ways to pass data to views:

• Weakly typed data: ViewData and ViewBag
• Strongly typed data: ViewModel

Both ViewData and ViewBag are dynamically resolved at runtime, which can often lead to runtime errors because they aren't type-safe and rely on Magic Strings.

Pass data using ViewData from Action:

public IActionResult About()
{
    ViewData["Message"] = "Hello World!";

    ViewData["User"] = new User()
    {
        Name = "Bob Northwind",
        Age = "35"
    };

    return View();
}

Show data using ViewData in View:

@{
  var user = ViewData["User"] as User;
}

<h2>ViewData["Message"]</h2>

<div>
    @user.Name<br>
    @user.Age<br>
</div>

So it is better to use ViewModel to pass data to views. Because it allows to take advantage of strong type checking, and the validity of types used in a view is checked at compile time.

Pass data using ViewModel from Action:

public IActionResult About()
{
    var viewModel = new UserViewModel()
    {
        Name = "Bob Northwind",
        Age = "35"
    };

    return View(viewModel);
}

Show data using ViewModel in View:

@model YourNamespace.ViewModels.UserViewModel

<div>
    @Model.Name<br>
    @Model.Age<br>
</div>