MVC troubleshooting: If the controller doesn't have a controller factory...

[This was originally posted at http://timstall.dotnetdevelopersjournal.com/mvc_troubleshooting_if_the_controller_doesnt_have_a_contro.htm]

I was toying around with the MVC pattern, and I kept getting this error while doing a tutorial:

 

'TaskList.Controllers.HomeController'. If the controller doesn't have a controller factory, ensure that it has a parameterless public constructor.
 

I'm no MVC expert, so I had to poke around a little. Ultimately, what seemed to fix it was making the database connection key in web.config match the key in the auto-generated dbml code.

 

The dbml code was failing on this line (in a file like "*.designer.cs"):

public TaskListDataContext() :
base(global::System.Configuration.ConfigurationManager.ConnectionStrings["TaskListDBConnectionString"].ConnectionString,

mappingSource)
{
    OnCreated();
}

I had modiefied my web.config, so there was no ConnectionString setting for "TaskListDBConnectionString", so that returned null, hence it failed. I needed to update web.config to something like so:

 

   

    name="TaskListDBConnectionString"

    connectionString="your_connection_here"

    providerName="System.Data.SqlClient"/>

 

To troubleshoot, I started stubbing out things one at a time - making an empty solution, downloading the final code, comparing the differences, etc...