Redirect to another page from _Layout.cshtml - asp.net-mvc

Question

How to redirect to another page within the _layout.cshtm page in asp.net core razor.
I am doing the verification and user is logged in, if not it will be redirected to another page.
#using Microsoft.AspNetCore.Identity
#using CronoParque.Model
#inject SignInManager<ApplicationUser> SignInManager
#inject UserManager<ApplicationUser> UserManager
#if (SignInManager.IsSignedIn(User))
{
<form asp-controller="Account" asp-action="Logout" method="post" id="logoutForm" class="navbar-right">
<ul class="nav navbar-nav navbar-right">
<li>
<a asp-page="/Account/Manage/Index" title="Manage">Ola #UserManager.GetUserName(User)!</a>
</li>
<li>
<button type="submit" class="btn btn-link navbar-btn navbar-link">Sair</button>
</li>
</ul>
</form>
}
else
{
// targeting here
}

Answer 1

Answer
#if (SignInManager.IsSignedIn(User))
{
// normal stuff
}
else if (!Context.Request.Path.ToString().Contains("/About"))
{
// If we aren't processing a request for the target page,
// then redirect to it.
Context.Response.Redirect("/About");
}
Maybe a Better Answer
The use case for your question might be to redirect unauthorized requests to a log in page. In that case, use the built-in razor pages authorization API.
services
.AddMvc()
.AddRazorPagesOptions(options => {
options.Conventions.AuthorizePage("/Contact");
});
The above code goes into the Startup > ConfigureServices method.
In the above example, the API redirects unauthorized requests for the /Contact.
See also: https://learn.microsoft.com/en-us/aspnet/core/security/authorization/razor-pages-authorization?view=aspnetcore-2.1#require-authorization-to-access-a-page