Entity Framework SaveChanges is not working

Question

I have a C# winforms application, and a SQL Server .mdf database file.

I tried to use Entity Framework. It works great when retrieving data from the database, but on calling .SaveChanges() nothing happens. No error, no exception, and no changes saved.

This issue just drives me crazy. I found a bunch of questions with nearly the same issue, but neither of the answers apply to my case.

My code looks like that:

using (World_ParkingEntities context = new World_ParkingEntities())
{
   client _client = context.CreateObject<client>();
   _client.name = name;
   _client.mobile_number = phoneNo;
   _client.email = email;
   context.AddToclients(_client);
   context.SaveChanges();
}

My connection string:

<add name="World_ParkingEntities" connectionString="metadata=res://*/Model1.csdl|res://*/Model1.ssdl|res://*/Model1.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\World_Parking.mdf;Integrated Security=True;User Instance=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient" /></connectionStrings>

Answer 1

The whole User Instance and AttachDbFileName= approach is flawed - at best! When running your app in Visual Studio, it will be copying around the .mdf file (from your App_Data directory to the output directory - typically .\\bin\\debug - where you app runs) and most likely , your INSERT works just fine - but you're just looking at the wrong .mdf file in the end!

If you want to stick with this approach, then try putting a breakpoint after the context.SaveChanges(); call - and then inspect the .mdf file with SQL Server Mgmt Studio Express - I'm almost certain your data is there.

The real solution in my opinion would be to

1. install SQL Server Express (and you've already done that anyway)

2. install SQL Server Management Studio Express

3. create your database in SSMS Express , give it a logical name (eg World_Parking )

4. connect to it using its logical database name (given when you create it on the server) - and don't mess around with physical database files and user instances. In that case, your connection string would be something like:

    Data Source=.\\\\SQLEXPRESS;Database=World_Parking;Integrated Security=True 

   and everything else is exactly the same as before...