[Pls Help] Why DI doesn't work as expected when using Azure Function

[tangdaowan]

When I use Azure Function to do some work, there comes a problem. Here are some details:

Please refer to the code snippet below. I am using denpendency injection to achieve Inversion of Control between classes and their dependencies. I have a class named MessagingEventGridPublisher with 2 constuctors, whose params are MessagingEventGridPublisher's dependencies. During function startup, I have DI this MessagingEventGridPublisher through services.AddSingleton<IEventGridPublisher, MessagingEventGridPublisher>(); . After I DI EventGridSecretOptions, I assume it will automatically resolve MessagingEventGridPublisher using the second constuctor. However it turns out I am wrong. It actually uses the first constructor to resolve MessagingEventGridPublisher. Do you know why it cannot be auto resolved as expected?

Besides, I want to call out that when using Azure Web APP, it works as expected.

public class MessagingEventGridPublisher : IEventGridPublisher
{
       public MessagingEventGridPublisher(EventGridManagedIdentityOptions options, TokenProvider tokenProvider, ILoggerX logger)
            : this(options, InitEventGridManagedIdentityClient(options, tokenProvider, logger), logger)
        {
        }

        public MessagingEventGridPublisher(EventGridSecretOptions options, ILoggerX logger)
            : this(options, InitEventGridSecretClient(options, logger), logger)
        {
        }
}

[CasperWSchmidt]

In general, having multiple public constructors is an anti-pattern when using DI. There's no way the DI framework can unambiguously decide which constructor to use. Why do you have the first constructor if you only use the second?

[jviau]

As @CasperWSchmidt multiple public ctors is an anti-pattern for DI. You will need to figure out how to specify which ctor to use (we use DryIoc, so see if there have a way to do that), manually register this service with a callback using the ctor you want, or remove the extra ctor.

Going to close this as it is a general DI question and not specific to the responsibility of this project.