Adding middleware to bot framework

Question

I am trying to add middleware into echo bot, that converts message into lower cases.

I have created Middleware class that inherits from IMiddleware

public class MiddlewareOne : IMiddleware
    {
        public async Task OnTurnAsync(ITurnContext turnContext, NextDelegate next, CancellationToken cancellationToken = default)
        {
            if(turnContext.Activity.Type == ActivityTypes.Message)
            {
                Debug.WriteLine(turnContext.Activity.Text);

                turnContext.Activity.Text = turnContext.Activity.Text.ToLower();
                await next(cancellationToken);

                Debug.WriteLine(turnContext.Activity.Text);
            }
            else
            {
                await next(cancellationToken);
            }
        }
    }
}

Now I am trying to add it into Startup.cs file. I found somewhere it should be added as Transient.

services.AddTransient<MiddlewareOne>();

Still, it's not working. I think MiddlewareOne class is okay, but how should I configure it in Startup.cs file?

Thank you

Answer 1

You have to register the middleware in your BotFrameworkAdapter descendant (e.g. BotFrameworkHttpAdapter) by calling the Use method in constructor. You can pass the middleware as a constructor parameter and DI will take care of activation.

An example (made without VS assistance)

public class MyAdapter : BotFrameworkHttpAdapter
{
    public MyAdapter(MiddlewareOne mw1, IConfiguration configuration, ILogger<BotFrameworkHttpAdapter> logger)
        : base(configuration, logger)
    {
        Use(mw1);
        // other code..
    }
}