Execute Razor Code from String

Nikhil Srivastava

10y1.4k.NET

Is there a way to execute text as Razor code? I am storing the HTML/JavaScript of a form in a database field. Everything works great except that I want to set values on the fields when they are pulled in and rendered in the view. For example:

 class="form-control-static" id="requested_by">@User.Identity.GetUserName()

Unfortunately, when this is pulled in and rendered, the value of the field is just the text "@User.Identity.GetUserName()" as opposed to the value returned from that method.

If you are curious as to why I am doing things this way, the form needs to be completely dynamic based on who is logging in. I have mulled over a few different solutions but this one seems to be the best. I am definitely open to some other ideas if you have them.

Here are the solutions that I was able to consider thus far:

Store field names and attributes in the database and dynamically create the form through iteration. The issue here is that some of the fields are grouped into fieldsets, some have addons, some parts require custom buttons, etc. This could definitely be done but I think it is way over-engineering and forcing a solution.

Build the form in HTML/JavaScript/Razor and store all of the field names in the database with associated user IDs. Conditionally show the fields based on whether or not the logged-in user has access to that field. Pseudo: @if(user.FormFields.Contains("field_name") ...

And the solution I am attempting now: Store all HTML/JavaScript/Razor in database as text and render with @Html.Raw(HtmlFromDatabase). As I said, this all works famously except for the Razor code which is not executing.

Any help or suggestions is much appreciated.

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Bhushan Gawale10y ago
Hey Nikhil,

Just out of curiosity I tried to build a demo MVC application with same approach as mentioned above and it worked great for me.
Let me brief you about it, and you can ignore this post if I have misunderstood your requirements or if this doesn't help you at all.

Created Db to store view html and stored sample html for entire view in one of the column.
Here is the sample source

This is what is stored in the database as View's HTML
@model TestModel
@using POC.Forums.DynamicMVCViews.Models

<br />
<h3>@Model.TestPropertyh3>
<p>@Model.TestProperty2p>
and below is the source to render
using FO = System.IO;
   public class TestController : Controller
   {
       // Private Variables
       private DynamicMVCEntities1 db = new DynamicMVCEntities1();
       private string viewPath = @"~/Views/Test/_TempView.cshtml";
       private string partialViewPath = @"~/Views/Test/_TempPartial.cshtml";

       public ActionResult Index()
       {
           // Initializing Model with Data
           TestModel viewModel = new TestModel();
           viewModel.TestProperty = "Data to be bound to the view!!";
           viewModel.TestProperty2 = "This is some other information!";

           // Entity framework source to get HTML from database
           CshtmlStore storeObj = db.CshtmlStore.Find(1);
           string sourceHtml = storeObj.ViewSource;

           // Forming absolute path of temp views
           var absolutePath = HttpContext.Server.MapPath(viewPath);

           if (FO.File.Exists(absolutePath))
           {
               // dumping HTML fetched from databsae on temp views on web server file system
               FO.File.WriteAllText(absolutePath, sourceHtml);

               // extracting data-bound html from the temp views using their Test controller
               var context = ViewRenderer.CreateController().ControllerContext;
               var renderer = new ViewRenderer(context);
               string viewHtml = renderer.RenderViewToString(viewPath, viewModel);

               // emptying temp views and returning HTML
               if (!string.IsNullOrEmpty(viewHtml))
               {
                   FO.File.WriteAllText(absolutePath, string.Empty);
                   return Content(viewHtml);
               }
           }
           return null;
       }
   }
Note - the ViewRenderer class which is used above is referred from here https://github.com/RickStrahl/WestwindToolkit/blob/master/Westwind.Web.Mvc/Utils/ViewRenderer.cs
Bhushan Gawale10y ago
All right, as I said - just an idea but didn't try hands on, However that's an interesting scenario! keep us updated if you find any other workaround.
Nikhil Srivastava10y ago
Thanks for your reply.
I am sorry but that's not a solution.
Bhushan Gawale10y ago
Did you take a look at
http://www.umbraworks.net/bl0g/rebuildall/2009/11/17/ASP_NET_MVC_and_virtual_views

Or you might want to do something like this (just an idea, not sure if it works)
Keep a Temp view folder under views and create a blank _virtualview.cshml inside it.
On runtime, i.e. while controller processing - fetch all your required cshtml from database and write it on _virtualview.cshtml and save the file(since it is on the file system)
Use method mentioned in this link to render view as string using controller context - http://stackoverflow.com/questions/3234003/render-view-programmatically-into-a-string
clean up the _virtualview.cshtml
return HTML string from controller
Hope this helps you.