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POParameter for "Delete" post method has blank attributes in ASP.NET MVC
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  1. POParameter for "Delete" post method has blank attributes in ASP.NET MVC
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    copied!<p>I'm having an issue in my MVC application (for making basic CRUD changes to a database) where the object parameter getting passed to my "Delete" post method has blank parameters, even though the object returned by the get method is correct. As a result, when I try to delete the object from the database I get the following exception:</p> <pre><code>A first chance exception of type 'System.ArgumentNullException' occurred in EntityFramework.dll System.ArgumentNullException: Value cannot be null. Parameter name: entity at System.Data.Entity.ModelConfiguration.Utilities.RuntimeFailureMethods.Requires(Boolean condition, String userMessage, String conditionText) at System.Data.Entity.DbSet`1.Remove(TEntity entity) at MvcApplication1.HomeController.Delete(ISBN bookToDelete) in C:\Users\MMcCrimmon\Documents\Visual Studio 2012\Projects\MortonPublishingDatabaseInterface\MvcApplication1\Controllers\HomeController.vb:line 103 </code></pre> <p>After a bit of digging I found this question: <a href="https://stackoverflow.com/questions/9485131/missing-something-in-delete-post-method-in-mvc-ef-4-1">Missing something in &quot;Delete&quot; post method in MVC (EF 4.1)</a>, which seems to be identical, but the answers there did not resolve my problem. What am I doing wrong here?</p> <p>Here's my controller code:</p> <pre class="lang-vb prettyprint-override"><code>' GET: /Home/Delete/5 Function Delete(ByVal id As String) As ActionResult Dim bookToDelete = _db.ISBNs.Find(id) Return View(bookToDelete) End Function ' POST: /Home/Delete/5 &lt;HttpPost()&gt; _ Function Delete(bookToDelete As ISBN) As ActionResult Dim originalBook = _db.ISBNs.Find(bookToDelete.Product_Code) Try _db.ISBNs.Remove(originalBook) _db.SaveChanges() Return RedirectToAction("Index") Catch exc As Exception Return View(originalBook) End Try End Function </code></pre> <p>and here's the view for the Delete page:</p> <pre class="lang-razor prettyprint-override"><code>@ModelType MvcApplication1.ISBN @Code ViewData("Title") = "Delete" Layout = "~/Views/Shared/_Layout.vbhtml" End Code &lt;h2&gt;Delete&lt;/h2&gt; &lt;h3&gt;Are you sure you want to delete this?&lt;/h3&gt; &lt;p/&gt; &lt;fieldset&gt; &lt;legend&gt;ISBN&lt;/legend&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.Product_Code)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.Product_Code) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.Title)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.Title) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.ISBN_UPC)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.ISBN_UPC) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.ManualName)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.ManualName) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.PgCount)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.PgCount) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.BookSize)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.BookSize) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.ColorOrBW)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.ColorOrBW) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.PageCount)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.PageCount) &lt;/div&gt; &lt;/fieldset&gt; @Using Html.BeginForm() @Html.AntiForgeryToken() @&lt;p&gt; &lt;input type="submit" value="Delete" /&gt; | @Html.ActionLink("Back to List", "Index") &lt;/p&gt; End Using </code></pre> <p>Following the answer for <a href="https://stackoverflow.com/questions/9485131/missing-something-in-delete-post-method-in-mvc-ef-4-1">Missing something in &quot;Delete&quot; post method in MVC (EF 4.1)</a>, here's the modified view (still doesn't work):</p> <pre class="lang-razor prettyprint-override"><code>@ModelType MvcApplication1.ISBN @Code ViewData("Title") = "Delete" Layout = "~/Views/Shared/_Layout.vbhtml" End Code &lt;h2&gt;Delete&lt;/h2&gt; &lt;h3&gt;Are you sure you want to delete this?&lt;/h3&gt; &lt;p/&gt; @Using Html.BeginForm() @Html.AntiForgeryToken() @&lt;fieldset&gt; &lt;legend&gt;ISBN&lt;/legend&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.Product_Code)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.Product_Code) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.Title)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.Title) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.ISBN_UPC)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.ISBN_UPC) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.ManualName)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.ManualName) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.PgCount)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.PgCount) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.BookSize)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.BookSize) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.ColorOrBW)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.ColorOrBW) &lt;/div&gt; &lt;div class="display-label"&gt; &lt;strong&gt;@Html.DisplayNameFor(Function(model) model.PageCount)&lt;/strong&gt; &lt;/div&gt; &lt;div class="display-field"&gt; @Html.DisplayFor(Function(model) model.PageCount) &lt;/div&gt; &lt;/fieldset&gt; @&lt;p&gt; &lt;input type="submit" value="Delete" /&gt; | @Html.ActionLink("Back to List", "Index") &lt;/p&gt; End Using </code></pre> <p>Full disclosure: I'm new to MVC, ASP, <em>and</em> VB.NET, so please forgive me if I'm making some rookie mistake here...</p>
 

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