EntityCommandExecutionException was unhandled

asp.net-mvc-3 c# entity-framework

Question

I am writing an application using EF 4.1 MVC3. I am trying to implement CRUD on it. The problem is that when i try to implement just first index page it gave me an error. I am using external database from central server. I am just trying a simple Registration form. I have first model class RegModel.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Registration.Models
{
    public class Register
    {
        public int Id { get; set; }
        public string UserName { get; set; }
        public string Password { get; set; }
        public string Email { get; set; }
        public string Address { get; set; }
    }
}

Then a RegModelContext.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Registration.Models
{
    public class Register
    {
        public int Id { get; set; }
        public string UserName { get; set; }
        public string Password { get; set; }
        public string Email { get; set; }
        public string Address { get; set; }
    }
}

My controller name is RegController.cs (I am just trying to implement Index first.) in controller. When i am executing my application it gave me error on return View(db.Registrant.ToString()); that "entitycommandexecutionexception was unhandled" "An error occurred while executing the command definition. See the inner exception for details."

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Registration.Models;
using System.Configuration;


namespace Registration.Controllers
{
    public class RegController : Controller
    {
        //
        // GET: /Reg/
        private string CmdStr = ConfigurationManager.ConnectionStrings["MyConn"].ConnectionString;      
        public ActionResult Index()
        {
            using (var db = new RegModelContext(CmdStr))
            {
                return View(db.Registrant.ToString());
            }

        }

    }
}

Then by using Index I create view for index (Index.cshtml):

@model IEnumerable<Registration.Models.Register>

@{
    Layout = null;
}

<!DOCTYPE html>

<html>
<head>
    <title>Index</title>
</head>
<body>
    <p>
        @Html.ActionLink("Create New", "Create")
    </p>
    <table>
        <tr>
            <th></th>
            <th>
                UserName
            </th>
            <th>
                Password
            </th>
            <th>
                Email
            </th>
            <th>
                Address
            </th>
        </tr>

    @foreach (var item in Model) {
        <tr>
            <td>
                @Html.ActionLink("Edit", "Edit", new { id=item.Id }) |
                @Html.ActionLink("Details", "Details", new { id=item.Id }) |
                @Html.ActionLink("Delete", "Delete", new { id=item.Id })
            </td>
            <td>
                @item.UserName
            </td>
            <td>
                @item.Password
            </td>
            <td>
                @item.Email
            </td>
            <td>
                @item.Address
            </td>
        </tr>
    }

    </table>
</body>
</html>

I am using this web.config file

<?xml version="1.0" encoding="utf-8"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=152368
  -->
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=4.3.1.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
  </configSections>
  <appSettings>
    <add key="ClientValidationEnabled" value="true" />
    <add key="UnobtrusiveJavaScriptEnabled" value="true" />
  </appSettings>
  <system.web>
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.WebPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      </assemblies>
    </compilation>
    <authentication mode="Forms">
      <forms loginUrl="~/Account/LogOn" timeout="2880" />
    </authentication>
    <pages>
      <namespaces>
        <add namespace="System.Web.Helpers" />
        <add namespace="System.Web.Mvc" />
        <add namespace="System.Web.Mvc.Ajax" />
        <add namespace="System.Web.Mvc.Html" />
        <add namespace="System.Web.Routing" />
        <add namespace="System.Web.WebPages" />
      </namespaces>
    </pages>
  </system.web>
  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
    <modules runAllManagedModulesForAllRequests="true" />
  </system.webServer>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
        <bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="3.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  <connectionStrings>
    <add name="MyConn" connectionString="Data Source=WIN-A32JMN2HC3A\SAIGMAMSSQL;Initial Catalog=Registration;User Id=SAIGMA110;Password=12345;"/>    
  </connectionStrings>
</configuration>
1
1
8/8/2012 11:00:51 AM

Accepted Answer

The problem is with this code:

string CmdStr = ConfigurationManager.ConnectionStrings["MyConn"].ConnectionString; 
using (var db = new RegModelContext(CmdStr))
{
    return View(db.Registrant.ToString());
}

First, you don't need to specify the connection string explicitly. By convention the Entity Framework will look for a matching connection string in your web.config file. Just make sure the name of the connection string matches the name of your DbContext.

Second, you are accessing a collection of Register objects in your database trough db.Registrant. Calling ToString() on it doesn't make any sense.

Your view expects a list of Registration.Models.Register instead of a string. Change your code to this:

using (var db = new RegModelContext())
{
    return View(db.Registrant.ToList());
}

Be aware that this is returning all Register items in your database. That could be a whole lot data. Maybe you want to implement paging or another type of filtering to make sure that everything works as expected.

3
6/27/2014 8:18:33 PM


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