ASP.NET ViewBag
last modified October 18, 2023
In this article we show how to pass data betweeen controllers and views in ASP.NET with ViewBag.
ASP.NET is a cross-platform, high-performance, open-source framework for building modern, cloud-enabled, web applications. It is developed by Microsoft.
A controller is a class which handles an HTTP request sent from a client. It retrieves model data and returns a response back to the client. A view displays data and handles user interaction.
A ViewBag is a controller property which is used to pass data from controllers to views. It is used for passing weakly-typed data. ViewBag is suitable for passing small amounts of data in and out of controllers and views.
If we want to pass strongly-typed data, we can use viewmodel.
ASP.NET ViewBag example
In the following example, we show how to use ViewBag.
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllersWithViews();
var app = builder.Build();
app.UseRouting();
app.UseEndpoints(endppoints =>
{
endppoints.MapDefaultControllerRoute();
});
app.Run("http://localhost:3000");
We set up controllers and views.
using Microsoft.AspNetCore.Mvc;
namespace ViewBagEx.Controllers;
public class HomeController : Controller
{
public IActionResult Index()
{
ViewBag.Now = DateTime.Now;
return View();
}
[HttpGet("words")]
public IActionResult Words()
{
var words = new List<string> { "red", "class", "rock", "war" };
ViewBag.Words = words;
return View();
}
}
In the controller we have two actions. The first returns the current datetime and the second a list of words.
ViewBag.Now = DateTime.Now;
We set the current datetime to the ViewBag.
var words = new List<string> { "red", "class", "rock", "war" };
ViewBag.Words = words;
Here we set a list of strings.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Home page</title>
</head>
<body>
<p>
@ViewBag.Now
</p>
</body>
</html>
In this view we display the current datetime. We access the bag via
@ViewBag.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Words</title>
</head>
<body>
<ul>
@{
foreach (var word in ViewBag.Words)
{
<li>@word</li>
}
}
</ul>
</body>
</html>
In this view, we display the words in an HTML list. We go through the list of words in a foreach loop.
$ dotnet watch
We start the application and navigate to localhost:3000
and localhost:3000/words.
In this article we have shown how to pass data betweeen controllers and views with ViewBag.
