# Passing data to view

## Passing Data from the Controller to the View <a href="#passing-data-from-the-controller-to-the-view" id="passing-data-from-the-controller-to-the-view"></a>

Controller actions are invoked in response to an incoming URL request. A controller class is where the code is written that handles the incoming browser requests. View templates can be used from a controller to generate and format an HTML response to the browser.

Controllers are responsible for providing the data required in order for a view template to render a response, However, view templates should **not d**o business logic or Interact with a database directly!&#x20;

{% hint style="info" %}
A view template should work only with the data that's provided to it by the controller. Maintaining this "separation of concerns" helps keep the code clean and testable!
{% endhint %}

### How to pass data from the controller to view?

Currently, the `Welcome` method in the `HelloWorldController` class takes a `name` and an `ID` parameter and then outputs the values directly to the browser. Rather than have the controller render this response as a string, change the controller to use a view template instead.&#x20;

The view template generates a dynamic response, which means that appropriate data must be passed from the controller to the view to generate the response. Do this by having the controller put the dynamic data (parameters) that the view template needs in a `ViewData` dictionary.&#x20;

The view template can then access the dynamic data. The `ViewData` dictionary is a dynamic object, which means **any type** can be used. The `ViewData` object has no defined properties until something is added.

{% hint style="info" %}
We can pass date to view by having the controller put the data that the view template needs in a `ViewData` dictionary (a structure to store key-value pairs provided by the ASP.NET framework)
{% endhint %}

### Let's make the changes to the code

Modify the `HelloWorldController`so it looks like this now

```csharp
using Microsoft.AspNetCore.Mvc;
using System.Text.Encodings.Web;

namespace MvcMovie.Controllers;

public class HelloWorldController : Controller
{
    public IActionResult Index()
    {
        return View();
    }
    public IActionResult Welcome(string name, int numTimes = 1)
    {
        ViewData["Message"] = "Hello " + name;
        ViewData["NumTimes"] = numTimes;
        return View();
    }
}
```

Create a Welcome view template named `Views/HelloWorld/Welcome.cshtml`.

You'll create a loop in the `Welcome.cshtml` view template that displays "Hello" `NumTimes`. Replace the contents of `Views/HelloWorld/Welcome.cshtml` with the following:

```cshtml
@{
    ViewData["Title"] = "Welcome";
}

<h2>Welcome</h2>

<ul>
    @for (int i = 0; i < (int)ViewData["NumTimes"]!; i++)
    {
        <li>@ViewData["Message"]</li>
    }
</ul>
```

Save your changes and browse to the following URL:

[`https://localhost:{PORT}/HelloWorld/Welcome?name=Rick&numtimes=4`](http://localhost:5184/helloworld/welcome?name=ram\&numtimes=4)

<figure><img src="https://2755360837-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FEISmCDQUIoLWiFMroqIo%2Fuploads%2FxSvKEg9VzLsA399vQWoJ%2Fimage.png?alt=media&#x26;token=a5dd2d58-7a6b-4368-b3ce-c25343667e14" alt=""><figcaption><p>output</p></figcaption></figure>

{% hint style="info" %}
Data was taken from the URL and passed to the controller using the MVC model binder. The controller packaged the data into a `ViewData` dictionary and passed that object to the view. The View then rendered the data as HTML to the browser!
{% endhint %}