Block the screen until user click the button

Thanks both of you for your reply , the issue is I have a login page in which I have model popup which comes when I have an entry into the database which I am saving in tempdata , the model appears but in controller where I render the view in which I have model popup after Review(login,model) I have the other logic like signin the user , so when the model popup comes it did not stop the popup till the user click the button on the popup rather the code runs completely from contorller and in controller i am redirectign the user to another action method and view 

Mark, Handling a modal popup in a web application and ensuring smooth interaction between your frontend JavaScript and backend controller methods can be tricky. Here’s a step-by-step approach to manage the modal popup based on TempData and coordinate actions between the frontend and backend in an ASP.NET MVC application effectively.

Step 1: Setup TempData in Controller

First, ensure that your controller sets a value in TempData when you want the modal to appear. For instance:

public ActionResult SomeAction()
{
    // Some operations
    TempData["ShowModal"] = "true";
    return View();
}

Step 2: Render the Modal Popup in View

In your view, you would typically check for the TempData value and use JavaScript or jQuery to show the modal. Here's an example using jQuery:

    
    

        ×
        
Some text in the Modal..
        Proceed
    

Step 3: Adjust Controller Logic

To ensure the modal does not disappear due to a view reload, you need to manage the post-modal interaction properly. Typically, you would not return a new view until the user has interacted with the modal. This can be managed by:

1. Using AJAX to handle form submissions or interactions that determine when to show the modal, thus avoiding a full page reload.
2. Separating the action that shows the modal from the action that handles the post-modal interaction.

Here’s an example of handling a modal interaction without reloading the view:

[HttpGet]
public ActionResult ShowPageWithModal()
{
    TempData["ShowModal"] = "true";
    return View();
}

[HttpPost]
public ActionResult HandleModalInteraction()
{
    // Process user response from modal
    return RedirectToAction("AnotherAction");
}

Step 4: Ensure TempData Persistence

TempData in ASP.NET MVC is meant for a single read. If you read it once, it's not available again. To keep TempData for the next request, you need to keep it:

public ActionResult SomeAction()
{
    TempData["ShowModal"] = "true";
    TempData.Keep("ShowModal"); // Keeps the TempData for the next request
    return View();
}

By managing the interaction flow between your frontend and backend correctly, you can control the modal behavior without unwanted page reloads. Use JavaScript or jQuery to manage client-side interactions, and let the server handle only the necessary parts of the process. This separation of concerns will help in maintaining a responsive and user-friendly interface.

To prevent the redirection from your controller and you can handle it on the client side after the user interacts with the modal popup.
For example:

public IActionResult MyAction()
{
    TempData["ShowModal"] = true;
    return View();
}