how to use Channel in Background Tasks

[godshades]

I want using chanel in backgroundservice, but I have this error when run my code, what I need to do.

Sorry for bad english

Unable to resolve service for type 'System.Threading.Channels.ChannelReader`1[ALGY.Model.SendMailChanel]' while attempting to activate 'ALGY.Util.SendEmailService'

public class SendMailChanel
    {
        public List<SendMail> SendMails { get; set; }
        public List<string> MailTos { get; set; }
    }

public class SendEmailService: BackgroundService
{
      
        private readonly ChannelReader<SendMailChanel> _channel;

        public HostedService(         
            ChannelReader<SendMailChanel> channel)
        {
            _channel = channel;
        }

        protected override async Task ExecuteAsync(CancellationToken cancellationToken)
        {
            await foreach (var item in _channel.ReadAllAsync(cancellationToken))
            {
                try
                {
                    // do your work with data
                }
                catch (Exception e)
                {
                    
                }
            }
        }
}

[ApiController]
[Route("api/data/upload")]
public class UploadController : ControllerBase
{
    private readonly ChannelWriter<SendMailChanel> _channel;

    public UploadController (
        ChannelWriter<SendMailChanel> channel)
    {
        _channel = channel;
    }

    public async Task<IActionResult> Upload([FromForm] FileInfo fileInfo)
    {
        SendMailChanel mailChanel = new SendMailChanel();
        mailChanel.SendMails = lstSendMail;
        mailChanel.MailTos = lstEmailTo;
        await _channel.WriteAsync(mailChanel);

        return Ok();
    }
}

Startup.cs
services.AddHostedService<SendEmailService>();

[davidfowl]

The error message is telling you that there's no service registered for the ChannelReader (and ChannelWriter). You can do something like this in ConfigureServices:

public void ConfigureServices(IServiceCollection services)
{
    // You should use a bounded channel, you'll need to adjust the queue size based on whatever performance metrics you have.
    var channel = Channel.CreateBounded<SendMailChanel>(100);
    services.AddSingleton(channel.Reader);
    services.AddSingleton(channel.Writer);
}