How to get Service instance using generic asp.net core

Question

I am working on a console application where I want to get the instance of a generic service type. Here is my implementation it gives me null.

 public class HelperService
        {
            private readonly ServiceCollection collection;
            private readonly IServiceProvider serviceProvider;
            public HelperService()
            {
                collection = new ServiceCollection();
                serviceProvider = collection.BuildServiceProvider();
            }
            public void RegisterService()
            {
                #region [register Services]
    
                collection.AddScoped<ICustomerService, CustomerService>();
    
                #endregion
    
            }
    
            public T? GetServiceInstance<T>() where T : class
            {
                return serviceProvider.GetService<T>()?? null;
            }
    
        }

var helperService = new HelperService();
helperService.RegisterService();
var result = helperService.GetServiceInstance<ICustomerService>(); // result is null

I want to implement generic service to which I will pass any service and it will give instance.

Guru Stron · Accepted Answer · 2022-06-22 14:23:34Z

2

You are adding service to collection after the IServiceProvider was build so it will not know anything about this newly added service, you need to add service before building the provider:

    public class HelperService
    {
        private readonly ServiceCollection collection;
        private readonly IServiceProvider serviceProvider;
        public HelperService()
        {
            collection = new ServiceCollection();
            #region [register Services]

            collection.AddScoped<ICustomerService, CustomerService>();

            #endregion
            serviceProvider = collection.BuildServiceProvider();
        }

        public T? GetServiceInstance<T>() where T : class
        {
            return serviceProvider.GetService<T>();
        }
    }

Also ?? null does not make much sense and can be removed.

And in general I would say that such wrapper is not very helpful, at least based on provided code.

answered Jun 22, 2022 at 14:23

Guru Stron

151k11 gold badges186 silver badges232 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Muhammad Kamran Over a year ago

Can you please let me how to register IConfiguration I am facing an issue registering it

Guru Stron Over a year ago

@MuhammadKamran try building configuration as it done for example here and than adding it to DI. This can be helpful.

Muhammad Kamran Over a year ago

I don't have appsetting.json file it is a console application

Guru Stron Over a year ago

@MuhammadKamran you can add it. Or add any other source of configuration (like environment variables and so on) with Add... call. What is the source of config for your app?

Muhammad Kamran Over a year ago

I have solve the configuration but now I am facing this error Unable to resolve service for type 'Microsoft.AspNetCore.Hosting.IHostingEnvironment

|

Collectives™ on Stack Overflow

How to get Service instance using generic asp.net core

1 Answer 1

7 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related