For those using ASP.NET Core 2.0 and looking for a more decoupled approach than vulcan's HtmlHelper, I recommend having a look at using a partial view with dependency injection.
Below is a simple implementation which can easily be molded to suit your needs.
The breadcrumb service (./Services/BreadcrumbService.cs):
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using System;
using System.Collections.Generic;
namespace YourNamespace.YourProject
{
public class BreadcrumbService : IViewContextAware
{
IList<Breadcrumb> breadcrumbs;
public void Contextualize(ViewContext viewContext)
{
breadcrumbs = new List<Breadcrumb>();
string area = $"{viewContext.RouteData.Values["area"]}";
string controller = $"{viewContext.RouteData.Values["controller"]}";
string action = $"{viewContext.RouteData.Values["action"]}";
object id = viewContext.RouteData.Values["id"];
string title = $"{viewContext.ViewData["Title"]}";
breadcrumbs.Add(new Breadcrumb(area, controller, action, title, id));
if(!string.Equals(action, "index", StringComparison.OrdinalIgnoreCase))
{
breadcrumbs.Insert(0, new Breadcrumb(area, controller, "index", title));
}
}
public IList<Breadcrumb> GetBreadcrumbs()
{
return breadcrumbs;
}
}
public class Breadcrumb
{
public Breadcrumb(string area, string controller, string action, string title, object id) : this(area, controller, action, title)
{
Id = id;
}
public Breadcrumb(string area, string controller, string action, string title)
{
Area = area;
Controller = controller;
Action = action;
if (string.IsNullOrWhiteSpace(title))
{
Title = Regex.Replace(CultureInfo.CurrentCulture.TextInfo.ToTitleCase(string.Equals(action, "Index", StringComparison.OrdinalIgnoreCase) ? controller : action), "[a-z][A-Z]", m => m.Value[0] + " " + char.ToLower(m.Value[1]));
}
else
{
Title = title;
}
}
public string Area { get; set; }
public string Controller { get; set; }
public string Action { get; set; }
public object Id { get; set; }
public string Title { get; set; }
}
}
Register the service in startup.cs after AddMvc():
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
services.AddTransient<BreadcrumbService>();
Create a partial to render the breadcrumbs (~/Views/Shared/Breadcrumbs.cshtml):
@using YourNamespace.YourProject.Services
@inject BreadcrumbService BreadcrumbService
@foreach(var breadcrumb in BreadcrumbService.GetBreadcrumbs())
{
<a asp-area="@breadcrumb.Area" asp-controller="@breadcrumb.Controller" asp-action="@breadcrumb.Action" asp-route-id="@breadcrumb.Id">@breadcrumb.Title</a>
}
At this point, to render the breadcrumbs simply call Html.Partial("Breadcrumbs") or Html.PartialAsync("Breadcrumbs").
