Dynamic navbar using _LoginPartial with .NET MVC - asp.net-mvc

Question

I have been trying to get this to work but doesn't seem to work. Basically I need a dynamic navbar. The pre-built .NET template actually has already generated a _LoginPartial.cshtml, which already changes the navbar depending on whether a user is login or not. I have been trying to edit the navbar so that it supports another level of change to check if a user is on a specific page then it will show more or less items depending on whether a boolean (showAll) is set to true or false. However is there a way to set the boolean based on the page? Currently I test it by changing manually and the logic works. I need a dynamic way to control it programmatically. Thank you for your help!
#using Microsoft.AspNetCore.Identity
#inject SignInManager<IdentityUser> SignInManager
#inject UserManager<IdentityUser> UserManager
#{bool showAll = false;}
#if (SignInManager.IsSignedIn(User) && showAll == true)
{
<ul class="nav navbar-nav mr-auto">
<li class="nav-item"><a asp-area="" asp-controller="Home" asp-action="Index" class="nav-link">Home</a></li>
<li class="nav-item"><a asp-area="" asp-controller="Home" asp-action="About" class="nav-link">About</a></li>
<li class="nav-item"><a asp-area="" asp-controller="Home" asp-action="Contact" class="nav-link">Contact</a></li>
</ul>
<form asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="#Url.Action("Index", "Home", new { area = "" })" method="post" id="logoutForm" class="navbar-right">
<ul class="nav navbar-nav navbar-right">
<li class="nav-item">
<a asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage" class="nav-link">Hello #UserManager.GetUserName(User)!</a>
</li>
<li class="nav-item">
<button type="submit" class="btn btn-link navbar-btn navbar-link">Logout</button>
</li>
</ul>
</form>
}
else if (SignInManager.IsSignedIn(User) && showAll == false)
{
<ul class="nav navbar-nav mr-auto">
<li class="nav-item"><a asp-area="" asp-controller="Home" asp-action="Index" class="nav-link">Home</a></li>
<li class="nav-item"><a asp-area="" asp-controller="Home" asp-action="About" class="nav-link">About</a></li>
</ul>
<form asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="#Url.Action("Index", "Home", new { area = "" })" method="post" id="logoutForm" class="navbar-right">
<ul class="nav navbar-nav navbar-right">
<li class="nav-item">
<a asp-area="Identity" asp-page="/Account/Manage/Index" title="Manage" class="nav-link">Hello #UserManager.GetUserName(User)!</a>
</li>
<li class="nav-item">
<button type="submit" class="btn btn-link navbar-btn navbar-link">Logout</button>
</li>
</ul>
</form>
}
else
{
<ul class="nav navbar-nav mr-auto">
<li class="nav-item"><a asp-area="" asp-controller="Home" asp-action="Index" class="nav-link">Home</a></li>
</ul>
<ul class="nav navbar-nav navbar-right">
<li class="nav-item"><a asp-area="Identity" asp-page="/Account/Register" class="nav-link">Register</a></li>
<li class="nav-item"><a asp-area="Identity" asp-page="/Account/Login" class="nav-link">Login</a></li>
</ul>
}

Answer 1

It depends a lot on what logic is behind that variable. If you can resolve it just from the login partial, you can certainly just add the logic there. For example, you could look at the current route to figure out whether you want that value to be true or not.
You could also build your own service that you inject there which then contains the logic. This can be useful if you end up doing more complicated stuff, as you should generally try to avoid too much logic inside views.
If the value is being set outside of the partial, you could also just use the ViewData dictionary to set it. This would allow you to set the value within your controllers, and then your partial view could just retrieve the value. Something like this:
#{
bool showAll = false; // default
if (ViewData.TryGetValue("NavigationShowAll", out var value) && value is bool)
{
showAll = (bool)value;
}
}
And then, in your controller, you can just do this:
public IActionResult DoSomething()
{
ViewData["NavigationShowAll"] = true;
return View();
}