How to make dynamic Url with specific Action and Controller in Asp.Net Core MVC controller?

Question

I want to generate navigation menu dynamically which follows default routing of my application with specific actions and controllers. I figured it out in MVC5 but I don't know how to do same in .Net Core MVC application.

What I've tried in MVC5 is as below:

View Model :

public class MenuViewModel
{
    // other props
    public string Link
    {
        get
        {
            UrlHelper url = new UrlHelper(HttpContext.Current.Request.RequestContext);
            return url.Action(this.Action != null ? this.Action : "StaticPage", this.Controller != null ? this.Controller : "StaticPage", new { pageName = this.PageTitle });
        }
    }
}

Global.asax :

public static List<MenuViewModel> SetMenuHeads()
{
    return
        General.DataModel.Menus
        .Where(m => m.IsHead)
        .Select(MenuViewModel.Set)
        .ToList();
}

General.cs :

public static string SubMenuGenerator(MenuViewModel menu)
{
    string subMenus = "";

    var subMenusList =
        DataModel.Menus
        .Where(m => m.ParentId == menu.ID)
        .Select(MenuViewModel.Set)
        .ToList();

    if (subMenusList.Count == 0)
        subMenus += "<li><a href=\"" + menu.Link + "\" class=\"external\"><span>" + menu.RenderTitle + "</span></a></li>";
    else
    {
        subMenus += "<li><a href=\"#\" class=\"external\"><span>" + menu.Title + "</span></a>";
        subMenus += "<ul>";
        foreach (var mnu in subMenusList)
        {
            subMenus += SubMenuGenerator(mnu);
        }
        subMenus += "</ul>";
        subMenus += "</li>";
    }

    return subMenus;
}

_Layout.cshtml :

<nav id="main-nav">
    <ul id="main-menu" class="sm-clean">
        <li><a href="@Url.Action("Index", "Home")" class="external"><span>Home</span></a></li>
        @{
            string menu = "";
            foreach (var menuItem in global_asax.SetMenuHeads())
            {
                menu += General.SubMenuGenerator(menuItem);
            }
        }
        
        @Html.Raw(menu)
    </ul>
</nav>

Now I want to try to do same in .net core but there is no class like HttpContext.Current.Request.RequestContext in .net core to make a url with its action and controller.

Any idea?

You can take a look at strathweb.com/2019/08/… and adapt it to your need. — Sai Gummaluri
– Sai Gummaluri, Commented Aug 17, 2020 at 17:24

LouraQ · Accepted Answer · 2020-08-18 07:38:51Z

In core, you can get all the paths through IActionDescriptorCollectionProvider.

If you want to make all routing into a navigation bar, then you need to add a custom middleware to the startup of the core project to pass the corresponding html to the _layout page.

Here is the complete example:

Custom Middleware:

  public class GetRoutingMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly IActionDescriptorCollectionProvider _actionDescriptorCollectionProvider;
        public GetRoutingMiddleware(RequestDelegate next, IActionDescriptorCollectionProvider actionDescriptorCollectionProvider)
        {
            _next = next;
            _actionDescriptorCollectionProvider = actionDescriptorCollectionProvider;
        }

        public async Task InvokeAsync(HttpContext context)
        {
             
            var allMenuList = _actionDescriptorCollectionProvider.ActionDescriptors.Items.Select(x => new
            {
                Action = x.RouteValues["Action"],
                Controller = x.RouteValues["Controller"],
                Name = x.AttributeRouteInfo != null ? x.AttributeRouteInfo.Name : "",
                Template = x.AttributeRouteInfo != null ? x.AttributeRouteInfo.Template : x.RouteValues["Controller"] + "/" + x.RouteValues["Action"],
            }).ToList(); 

            var menu = allMenuList.GroupBy(x => x.Controller).ToList();
            var subMenus = "";
            foreach (var subMenuList in menu)
            {
                if (subMenuList.Count() > 0)
                {
                    subMenus += "<li class=\"nav-item dropdown\"><a href=\"#\" class=\"nav-link dropdown-toggle\" role=\"button\" data-toggle=\"dropdown\" aria-haspopup=\"true\" aria-expanded=\"false\"><span>" + subMenuList.Key + "</span></a>";
                    subMenus += "<div class=\"dropdown-menu\" arialabelledby=\"navbarDropdown\">";
                    foreach (var mnu in subMenuList)
                    {
                        subMenus += "<a class=\"dropdown-item\" href=\"/" + mnu.Template + "\">" + mnu.Action + "</a>";
                    }
                    subMenus += "</div>";
                    subMenus += "</li>";
                }
                else
                {
                    subMenus += "<li class=\"nav-item\"><a href=\"/" + subMenuList.FirstOrDefault().Template + "\" class=\"nav-link\"><span>" + subMenuList.Key + "</span></a></li>";
                }
            }
            context.Items.Add("routeMenu", subMenus);
            await _next.Invoke(context); 
        } 
    }

Add this middleware to Configure method :

   public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            //...

            app.UseStaticFiles();

            app.UseMiddleware<GetRoutingMiddleware>(); 

            app.UseRouting();

            //....

        }

In _Layout.cshtml:

@{
    var menus = Context.Items["routeMenu"];
}

 <nav class="navbar navbar-expand-lg navbar-light bg-light">
            <div class="collapse navbar-collapse" id="navbarSupportedContent">
                <ul class="navbar-nav mr-auto">
                    @Html.Raw(menus)
                </ul>
            </div>
        </nav>

I made some changes to the style, you can change it according to your needs.

Here is the test result:

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