ASP.NET Mvc 5 return View with seo friendly url

Question

I'm looking for a way to return a View based on an Id, but adding a friendly url part when returning.

I know I can pass in the id and name when I have this data available, e.g. by using:

Url.Action("Index", "Cat", new { id = model.ID, seoname = model.SEO });


[AllowAnonymous]
[Route("Cat/{id?}/{seoname?}")]
public ActionResult Index(int? id = null, string seoname = null) {
   // do something with id and create viewmodel 

   // in case I get redirect from the SelCat actionresult:
   if (id.HasValue and string.IsNullOrEmpty(seoname)) { 
      // look in the database for title by the given id
      string seofriendlyTitle = ...;
      RouteData.Values.AddOrSet("seoname", seofriendlyTitle);
   }

   return View(viewmodel);
}

this code above is not a problem. The problem occurs when I submit a form (dropdownlist) where I only have the Id available.

[HttpPost]
[AllowAnonymous]
[Route("Cat/SelCat/{form?}")]
public ActionResult SelCat(FormCollection form) 
{ 
   string selectedValues = form["SelectedCat"];
   // ...
   int id = selectedCatID;
   return RedirectToAction("Index", new { id = id });
} 

In case I redirect from the SelCat action to the Index action with only an ID I want to search the seofriendly name and when returning the view. I was hoping that the url had the friendly url part.

   // in case I get redirect from the SelCat actionresult:
   if (id.HasValue and string.IsNullOrEmpty(seoname)) { 
      // look in the database for title by the given id
      string seofriendlyTitle = ...;
      RouteData.Values.AddOrSet("seoname", seofriendlyTitle); // <-- does not alter url
   }

How can I make my url seo friendly when returning a View in my Controller Action when only an ID is given? Setting the RouteData.Values. does not seem to add the part to the url.

Answer 1

You can create a custom RouteBase subclass and load all of your URLs into a cache. Then all you need is the id (presumably based on a primary key) to lookup the URL. Note that you can make the id either Guid (as shown) or int.

public class PageInfo
{
    // VirtualPath should not have a leading slash
    // example: events/conventions/mycon
    public string VirtualPath { get; set; }
    public Guid Id { get; set; }
}

public class CustomPageRoute
    : RouteBase
{
    private object synclock = new object();

    public override RouteData GetRouteData(HttpContextBase httpContext)
    {
        RouteData result = null;

        // Trim the leading slash
        var path = httpContext.Request.Path.Substring(1);

        // Get the page that matches.
        var page = GetPageList(httpContext)
            .Where(x => x.VirtualPath.Equals(path))
            .FirstOrDefault();

        if (page != null)
        {
            result = new RouteData(this, new MvcRouteHandler());

            // Optional - make query string values into route values.
            this.AddQueryStringParametersToRouteData(result, httpContext);

            // TODO: You might want to use the page object (from the database) to
            // get both the controller and action, and possibly even an area.
            // Alternatively, you could create a route for each table and hard-code
            // this information.
            result.Values["controller"] = "CustomPage";
            result.Values["action"] = "Details";

            // This will be the primary key of the database row.
            // It might be an integer or a GUID.
            result.Values["id"] = page.Id;
        }

        // IMPORTANT: Always return null if there is no match.
        // This tells .NET routing to check the next route that is registered.
        return result;
    }

    public override VirtualPathData GetVirtualPath(RequestContext requestContext, RouteValueDictionary values)
    {
        VirtualPathData result = null;

        PageInfo page = null;

        // Get all of the pages from the cache.
        var pages = GetPageList(requestContext.HttpContext);

        if (TryFindMatch(pages, values, out page))
        {
            if (!string.IsNullOrEmpty(page.VirtualPath))
            {
                result = new VirtualPathData(this, page.VirtualPath);
            }
        }

        // IMPORTANT: Always return null if there is no match.
        // This tells .NET routing to check the next route that is registered.
        return result;
    }

    private bool TryFindMatch(IEnumerable<PageInfo> pages, RouteValueDictionary values, out PageInfo page)
    {
        page = null;
        Guid id = Guid.Empty;

        // This example uses a GUID for an id. If it cannot be parsed,
        // we just skip it.
        if (!Guid.TryParse(Convert.ToString(values["id"]), out id))
        {
            return false;
        }

        var controller = Convert.ToString(values["controller"]);
        var action = Convert.ToString(values["action"]);

        // The logic here should be the inverse of the logic in 
        // GetRouteData(). So, we match the same controller, action, and id.
        // If we had additional route values there, we would take them all 
        // into consideration during this step.
        if (action == "Details" && controller == "CustomPage")
        {
            page = pages
                .Where(x => x.Id.Equals(id))
                .FirstOrDefault();
            if (page != null)
            {
                return true;
            }
        }
        return false;
    }

    private void AddQueryStringParametersToRouteData(RouteData routeData, HttpContextBase httpContext)
    {
        var queryString = httpContext.Request.QueryString;
        if (queryString.Keys.Count > 0)
        {
            foreach (var key in queryString.AllKeys)
            {
                routeData.Values[key] = queryString[key];
            }
        }
    }

    private IEnumerable<PageInfo> GetPageList(HttpContextBase httpContext)
    {
        string key = "__CustomPageList";
        var pages = httpContext.Cache[key];
        if (pages == null)
        {
            lock(synclock)
            {
                pages = httpContext.Cache[key];
                if (pages == null)
                {
                    // TODO: Retrieve the list of PageInfo objects from the database here.
                    pages = new List<PageInfo>()
                    {
                        new PageInfo() 
                        { 
                            Id = new Guid("cfea37e8-657a-43ff-b73c-5df191bad7c9"), 
                            VirtualPath = "somecategory/somesubcategory/content1" 
                        },
                        new PageInfo() 
                        { 
                            Id = new Guid("9a19078b-2d7e-4fc6-ae1d-3e76f8be46e5"), 
                            VirtualPath = "somecategory/somesubcategory/content2" 
                        },
                        new PageInfo() 
                        { 
                            Id = new Guid("31d4ea88-aff3-452d-b1c0-fa5e139dcce5"), 
                            VirtualPath = "somecategory/somesubcategory/content3" 
                        }
                    };

                    httpContext.Cache.Insert(
                        key: key, 
                        value: pages, 
                        dependencies: null, 
                        absoluteExpiration: System.Web.Caching.Cache.NoAbsoluteExpiration, 
                        slidingExpiration: TimeSpan.FromMinutes(15), 
                        priority: System.Web.Caching.CacheItemPriority.NotRemovable, 
                        onRemoveCallback: null);
                }
            }
        }

        return (IEnumerable<PageInfo>)pages;
    }
}

You can register the route with MVC like this.

routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

// Case sensitive lowercase URLs are faster. 
// If you want to use case insensitive URLs, you need to
// adjust the matching code in the `Equals` method of the CustomPageRoute.
routes.LowercaseUrls = true;

routes.Add(
    name: "CustomPage", 
    item: new CustomPageRoute());

routes.MapRoute(
    name: "Default",
    url: "{controller}/{action}/{id}",
    defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);

With the above registration, you can generate a URL based off of an id by using @Html.ActionLink("A link to a page", "Details", "CustomPage", new { id = "9a19078b-2d7e-4fc6-ae1d-3e76f8be46e5" }, null). This will take you to an action named Details on a controller named CustomPageController (which can then return a view).

BTW - Routing is a separate concern from "returning a view", so your question is a bit confusing.

Answer 2

You will have to look in the database for the SEO friendly slug before redirecting and include it in the url, otherwise it's too late:

[HttpPost]
[AllowAnonymous]
[Route("Cat/SelCat/{form?}")]
public ActionResult SelCat(FormCollection form) 
{ 
    string selectedValues = form["SelectedCat"];
    // ...
    int id = selectedCatID;

    // look in the database for title by the given id
    string seofriendlyTitle = ...;
    return RedirectToAction("Index", new { id = id, seoname = seofriendlyTitle });
}

Once you have reached the Index action it is already too late to be able to alter the url that is shown on the client, unless you make an additional redirect (which of course would be insane).