How to check for specific parameter in Microsoft System.Commandline CLI

Question

I am currently configuring a CLI command with the package System.CommandLine.

In my CommandClass I have added an option for the user to select if he wants to do a dry-run. How do I check if the user has given that specific paramter?

Snippets of my code:

using System.CommandLine;
namespace MyApp.Cli.commands;

public class MyCommandClass : Command 
{
    public MyCommandClass()
        : base("start-my-command", "test the functionalities of system.commandline")
    {
        AddOption(new Option<bool>(new string[] { "--dry-run", "-d" }, "Simulate the actions without making any actual changes"));
    }

    public new class Handler : ICommandHandler
    {
        private readonly ILogger<MyCommandClass> _log;

        public Handler(ILogger<MyCommandClass> log)
        {
            _log = log;
        }

        public async Task<int> InvokeAsync(InvocationContext context)
        {
            var isDryRun = /* check if the user has provided the parameter "--dry-run" */

            if (isDryRun)
            {
                _log.LogInformation("is dry run");
            }
            else
            {
                _log.LogInformation("is no dry run");
            }
        }
    }
    
}

I already tried to do var isDryRun = context.ParseResult.GetValueForOption<bool>("--dry-run"); but this just gives me the following error: Argument 1: cannot convert from 'string' to 'System.CommandLine.Option'.

Please help, thanks.

Answer 1

Instead of using context.ParseResult.GetValueForOption("--dry-run") it's better to refer directly to the Option object created when adding the option to the command.

public class MyCommandClass : Command 
{
    // Declaring the dry-run option at the class level
    private Option<bool> dryRunOpt = new Option<bool>(
        aliases: new[] { "--dry-run", "-d" },
        description: "Run in dry mode without actual changes"
    );

    public MyCommandClass() : base("start-my-command", "Testing the functionalities")
    {
        // Adding the dry-run option to our command
    // This line is important :)
        AddOption(dryRunOpt);
    }

    public class Handler : ICommandHandler
    {
        private readonly ILogger<MyCommandClass> logger;

        public Handler(ILogger<MyCommandClass> logger)
        {
            this.logger = logger;
        }

        public async Task<int> InvokeAsync(InvocationContext context)
        {
            // Checking the dry-run option value
            var isDryRun = context.ParseResult.GetValueForOption(dryRunOpt);

            if (isDryRun)
            {
                logger.LogInformation("Running in dry-run mode.");
            }
            else
            {
                logger.LogInformation("Executing normal operation.");
            }

            // ...

            return 0;
        }
    }
}