Using Microsoft Extension Dependency Injection on WinForms in C#

Question

My knowledge in DI is very limited. I am developing a WinForm project in a solution which every else where in the solution, Microsoft Extension Dependency Injection have been used.

I need to pass some dependency into constructor of MainForm:

public partial class MainForm : Form
{
   public MainForm(ISomeThing someThing)
   {
   }
}

In the Main method, an instance of MainForm is passed to Run method:

[STAThread]
static void Main()
{
    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);
    Application.Run(new MainForm());
}

I tried to use DI to instantiate an instance for Mainform by having a service provider:

private static IServiceProvider ServiceProvider { get; set; }

and then assigning to it an object as follows:

static void ConfigureServices()
{
   var services = new ServiceCollection();
   services.AddTransient<ISomeThing, SomeThing>();
   ServiceProvider = services.BuildServiceProvider();
}

And then call ConfigureServices() in Main() as follows:

static void Main()
{
   Application.EnableVisualStyles();
   Application.SetCompatibleTextRenderingDefault(false);
   ConfigureServices();
   Application.Run(ServiceProvider.GetService(MainForm));
}

However, I get a compilation error: "MainForm is a type, which is not valid in the given context"

I found the following links which uses similar approach using SimpleInjector or Unity but I do not know how to use this with this kind of DI? or I have to use other DI?

Thanks

Answer 1

You're trying to get the System.Type instance that corresponds to that class.

That's what the typeof() keyword does:

GetService(typeof(MainForm))

Note that you'll also need to cast the result to Form.

Answer 2

I've added a helper function to my code to make this more readable:

public static T? GetService<T>() where T : class
{
   return (T?)ServiceProvider.GetService(typeof(T));
}

//was:
// thing = (iThing)Program.ServiceProvider.GetService(typeof(iThing));

//now:
thing = Program.GetService<iThing>();