Sorry, an error occurred while processing your request. in MVC3 Model Entities

Question

I am new in MVC, made an app that works on my local machine (Windows 7 with SQLExpress) but when I deploy live on Windows 2008 R2, SQL 2008 R2 and IIS7, I get this error: "Sorry, an error occurred while processing your request"

Below are snippets of the code in question:

WEB.CONFIG connectionStrings

add name="RentalEntities" connectionString="Data Source=[ServerName];Initial Catalog=[DatabaseName];Integrated Security=True" providerName="System.Data.SqlClient"

HOMECONTROLLER

namespace Rental.Controllers    
{    
   RentalEntities rentalDB = new RentalEntities();

   ...

   public ActionResult Index()

   {             
      var listings = from l in rentalDB.Listings select l;
      return View(listings.ToList());    
   }
}

HOME/INDEX.CSHTML

@model List<Rental.Models.Listing>

@foreach (var listing in Model)    
{    
    @listing.ListingName <br />     
}

The error occurred on this line @foreach (var listing in Model), something to do with being null - note that NONE of the fields in the database are null. Any help will be appreciated.

Below is the full error message: [ where line 13 is: foreach (var listing in Model)

Sorry, an error occurred while processing your request.

System.NullReferenceException: Object reference not set to an instance of an object. at ASP._Page_Views_Home_Index_cshtml.Execute() in c:\inetpub\wwwroot\projects\Rentals\Views\Home\Index.cshtml:line 13 at System.Web.WebPages.WebPageBase.ExecutePageHierarchy() at System.Web.Mvc.WebViewPage.ExecutePageHierarchy() at System.Web.WebPages.StartPage.ExecutePageHierarchy() at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass1c.<InvokeActionResultWithFilters>b__19() at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)

score 0 · Answer 1 · edited Dec 17 '13 at 16:23

0

What has happened here is that you've passed a null value into the Model for index.cshtml. The code is foreach'ing over null.

Debugging this in Prod:

How many rows are in the Listing table on the Prod server?
Does your LINQ To SQL .dbml refer exactly to the connection string in your web.config, or does it have a hidden connection string buried within the .designer.cs?

Try setting up some debug info on INDEX.CSHTML

@(Model==null) //will write to page whether the model data being passed is null.

Debugging this in Dev/Test:

To help debug why it's null, set a breakpoint for yourself on the line in Index(). Set it on return View(listings.ToList());. Is it actually null? Then set a breakpoint on the check for null in your View.

Before foreach, run a check for null:

@if (Model != null)
{
     foreach (var foo in Model)
     {
       //your code
     }
}
else
{
    @: Model Is null!
}

edited Dec 17 '13 at 16:23

John Gibb

10,603
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answered Apr 15 '11 at 17:13

p.campbell

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I did the above if else, and it did not like that part @"Model Is null!". When I removed it, it runs and shows nothing, which means the Model is null. Why is that? I have set the database and entities properly... – Charlako Apr 15 '11 at 18:18
@Charl: see the update about your .dbml. I'd assumed you're using LINQ To SQL and not EF. – p.campbell Apr 15 '11 at 18:39
can you please elaborate on your last comment please, I don't understand what you mean when you say "see the update about your .dbml". Like you can see on my controller above, I used entities: RentalEntities rentalDB = new RentalEntities(); All of this worked on my dev and my friends computer locally... I am very new with MVC. – Charlako Apr 15 '11 at 18:47
@Char: I meant that I'd updated my answer to include a bullet about .dbml. It's all about what connection string your .dbml is using. Check out your .dbml.designer.cs file. Does it have a connection string buried in the first constructor? See here: http://i.imgur.com/wbu0a.png – p.campbell Apr 15 '11 at 20:19

Sorry, an error occurred while processing your request. in MVC3 Model Entities

1 Answers1