[Solved] I am trying to save to my database using EntityFramework but keep running into exceptions. What am I doing wrong?

See more:

C#

.NET

C#4.0

.NET4

EF4.0

I am just starting out with my first Entity Framework project built from scratch, to teach myself. I have encountered EF projects before at work but they were already pre-built by the time I had come along so I just had to tweak and maintain them, never build a EF project from the ground up.

I have Googled this error and all I got were a bunch of very wordy StackOverflow posts that had link upon link and would've required me to spend the whole day reading the fricking encyclopedia for just a simple question.

I have a SQL Server Express instance named CTI-BCH-W7\SQLEXPRESS.

I am making a little CRM program to manage clients I tutor in math and science as a side business. I designed a DB with three tables: Customers, Students, and Sessions.

Then I built a TutoringManagerObjects DLL by using EF4.1 Database first. I used the proper NuGet packages and the DLL builds just fine.

Maybe I am getting something wrong in my app.config. Here is the app.config of my DLL (the layer that holds the entities):

<?xml version="1.0" encoding="utf-8"?>
<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>
  <connectionStrings>
    <add name="TutoringEntities" connectionString="metadata=res://*/TutoringModel.csdl|res://*/TutoringModel.ssdl|res://*/TutoringModel.msl;provider=System.Data.SqlClient;provider connection string="data source=CTI-BCH-W7\SQLEXPRESS;initial catalog=Tutoring;integrated security=True;multipleactiveresultsets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
  </connectionStrings>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="Data Source=.\SQLEXPRESS; Integrated Security=True; MultipleActiveResultSets=True" />
      </parameters>
    </defaultConnectionFactory>
  </entityFramework>
</configuration>

In my TutoringManager.Context.cs file (which is the generated code for the TutoringManager.Context.tt template), I have

//------------------------------------------------------------------------------
// <auto-generated>
//    This code was generated from a template.
//
//    Manual changes to this file may cause unexpected behavior in your application.
//    Manual changes to this file will be overwritten if the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

using System;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;

namespace TutoringManagerObjects
{
    public partial class TutoringEntities : DbContext
    {
        public TutoringEntities()
            : base("name=TutoringEntities")
        {
        }
    
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            throw new UnintentionalCodeFirstException();
        }
    
        public DbSet<Customer> Customers { get; set; }
        public DbSet<Session> Sessions { get; set; }
        public DbSet<Student> Students { get; set; }
    }
}

Then I made a Windows Forms application and used the Entities at the Data Source via Data menu -> Add New Data Source. Everything added OK and my objects added to the WinForms app just fine.

Now when I hit a Save button the code calls (I am *trying* to use the Model-View-Presenter pattern):

void buttonSave_Click(object sender, EventArgs e)
{
    try
    {
        _presenter.SaveNewCustomer(new Customer
        {
            FirstName = firstNameTextBox.Text,
            LastName = lastNameTextBox.Text,
            Address1 = address1TextBox.Text,
            Address2 = address2TextBox.Text,
            City = cityTextBox.Text,
            State = stateTextBox.Text,
            ZIP = zIPTextBox.Text,
            ContactPhone1 = contactPhone1TextBox.Text,
            ContactPhone2 = contactPhone2TextBox.Text,
            Email = emailTextBox.Text
        });
    }
    catch (Exception exception)
    {
        MessageBox.Show(exception.Message,
            Application.ProductName,
            MessageBoxButtons.OK,
            MessageBoxIcon.Stop);
    }
}

In the Presenter, I do:

internal void SaveNewCustomer(Customer customerToSave)
{
    if (customerToSave == null)
        return;

    using (var context = new TutoringEntities())
    {
        context.Customers.Add(customerToSave);
        context.SaveChanges();
        IsModified = false; // turn dirty bit off now that we've saved
    }

    OnNewCustomerSaved();   // inform UI
}

When I click my Save button I get the message box

---------------------------
TutoringManager
---------------------------
The type initializer for 'System.Data.Entity.Internal.AppConfig' threw an exception.
---------------------------
OK   
---------------------------

Here is the app.config of my WinForms app:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <connectionStrings>
    <add name="TutoringDatabase"
         connectionString="metadata=res://*/TutoringModel.csdl|res://*/TutoringModel.ssdl|res://*/TutoringModel.msl;provider=System.Data.SqlClient;provider connection string="data source=CTI-BCH-W7\SQLEXPRESS;initial catalog=Tutoring;integrated security=True;multipleactiveresultsets=True;App=EntityFramework""
         providerName="System.Data.EntityClient"/>
  </connectionStrings>
  <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>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="Data Source=.\SQLEXPRESS; Integrated Security=True; MultipleActiveResultSets=True" />
      </parameters>
    </defaultConnectionFactory>
  </entityFramework>
</configuration>

Do I have something configured inproperly? What am I doing wrong? I am new to EntityFramework so I can't quite figure it out.