Example of how to define commands that require components to be injected

[ninjaboy]

hi @natemcmaster ,

I am struggling to find an example of how it is envisioned to define commands that accept custom dependencies injected using declarative syntax.
Is there any place where you could point me to see an example of how to do this?

[ninjaboy]

To clarify myself:
app.Execute only accepts command type to be execute, andthere's no way to control the creation of the command itself provided by the library
Is my understanding right?

I ended up creating a weird closure to perform injection in the form of:

        private static CommandLineApplication DefineApp(IContainer container)
        {
            var app = new CommandLineApplication
            {
            };
            app.Command("m", cmd => MCommand.ConfigureCommand(container, cmd), false);
            return app;
         }


public class M{

   public M(...dependencies injected here...)
         { this.dep1 = dep1; }

    public Do(int n)
    {  dep1.Do(n);  }

    public static void ConfigureCommand(IContainer container, CommandLineApplication command)
        {
            var number = command.Argument("n", "number").IsRequired();
            command.HelpOption();
            command.OnExecute(() =>
            {
                CommandExecuteHandler(container, command, number);
            });
        }
        private static void CommandExecuteHandler(IContainer container, CommandLineApplication command, CommandArgument number)
        {
            try
            {
                var commandContext = container.Resolve<M>();
               commandContext.Do(number);
             } catch(){}
       }
}

This resolves dependency injection but obviously requires too much boilerplate to wire up simple things.

AND prevents me from using declarative API syntax

[natemcmaster]

I haven't currently created a way to do this. The current requirement for .Execute<TApp>() is that type TApp has a parameter-less constructor.

But, if I were to do this, I would favor constructor injection and add an overload like .Execute<TApp>(System.IServiceProvider services, string[] args). Would supporting something like this work?

class Program
{
    public static int Main(string[] args)
    {
        System.IServiceProvider container = CreateServiceContainer();
        return CommandLineApplication.Execute<App>(container, args);
    }

    static System.IServiceProvider CreateServiceContainer()
    {
        // ... 
    }
}

class App
{
    public App(ManifestCommand command,IContainer container, ILogger logger)
    { }

    [Argument(0)]
    public int Number { get; }
}

[kt81]

@natemcmaster
I like your plan.

btw, the DI sample in this site works correctly.
https://brainwipe.github.io/dotnet/core/marten/2017/11/07/injecting-logging-into-marten/
But, it requires to instantiate all commands without ReflectionAppBuilder so attribute-based settings are ignored.

[natemcmaster]

I've added support for this. See the sample I wrote here: https://github.com/natemcmaster/CommandLineUtils/blob/cc4d6015bb91eb16f2cb2bb867b858fe0f979d8c/samples/Conventions/DependencyInjection.cs

This will be out in 2.2.0-beta, or you can try the nightly builds (see README). Give it a shot and let me know if it works for you.