ASP. Net core using Autofac

ASP.NET Core Use Autofac

asp.net core Use autofac

1. install Autofac and Autofac.Extensions.DependencyInjection nuget package
2. modify Program class

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .UseServiceProviderFactory(new AutofacServiceProviderFactory())
                .ConfigureWebHostDefaults(webBuilder =>
                {
    
                    webBuilder.UseStartup<Startup>();
                });

3. modify Startup class , Add... To the class ConfigureContainer Method

Property introduction ：
RegisterAssemblyTypes： Register assembly type
AsImplementedInterfaces： Implemented interface
InstancePerDependency： Instance dependencies
PropertiesAutowired： Attribute auto connect ( Attribute auto Injection )

        /// <summary>
        ///  To configure Autofac Container replaces Microsoft DI
        /// </summary>
        /// <param name="containerBuilder"></param>
        public void ConfigureContainer(ContainerBuilder builder)
        {
    
            //  Single service class registration 
            builder.RegisterType<UserService>().As<IUserService>().InstancePerLifetimeScope();

            //  Multiple service classes , Assembly registration  //
            //  This is the assembly service that registers other projects 
            var basePath = AppContext.BaseDirectory;
            //DALService Assembly namespace 
            string DALPath = Path.Combine(basePath, "GraduationProject.DAL.dll");
            Assembly DAL = Assembly.LoadFrom(DALPath);
            //BLLService Assembly namespace 
            string BLLPath = Path.Combine(basePath, "GraduationProject.BLL.dll");
            Assembly BLL = Assembly.LoadFrom(BLLPath);
            builder.RegisterAssemblyTypes(DAL).InstancePerDependency().PropertiesAutowired();
            builder.RegisterAssemblyTypes(BLL).AsImplementedInterfaces().InstancePerDependency().PropertiesAutowired();

            //  This is to register the assembly service under the same project 
            builder.RegisterAssemblyTypes(typeof(Program).Assembly)
            .Where(t => t.Name.EndsWith("Service"))
            .AsImplementedInterfaces()
            .InstancePerLifetimeScope();
        }

Or new AutofacModelRegister Configuration class

//  Inherited from  Autofac.Model 
public class AutofacModelRegister : Autofac.Module
    {
    
      // rewrite Autofac The Conduit Load Method , Register injection here 
     protected override void Load(ContainerBuilder builder)
     {
    
         //  The configuration logic is the same as above 
         builder.RegisterType<UserService>().As<IUserService>();
 　　 }
}

//  And then in startup Class ConfigureContainer Method , To configure 
public void ConfigureContainer(ContainerBuilder builder)
{
    
    //  Direct use Autofac Sign up for our custom  
    builder.RegisterModule(new AutofacModuleRegister());
    //  Service project assembly 
    //Assembly service = Assembly.Load("XXX.Service");
    //  Service interface project assembly 
    //Assembly iservice = Assembly.Load("XXX.IService");
    //builder.RegisterAssemblyTypes(service, iservice).Where(t => t.FullName.EndsWith("Service") && !t.IsAbstract)
    //.InstancePerLifetimeScope()
    //.AsImplementedInterfaces();
}

Be careful ： If the service that needs to be injected doesn't interface , that builder.RegisterAssemblyTypes Just pass an assembly OK 了 . If the service and interface are in the same project , It also needs to transfer two assemblies .

4. controller Use in

    [ApiController]
    [Route("[controller]")]
    public class HomeController : ControllerBase
    {
    
        private readonly IUserService _userService;

        public HomeController(IUserService userService)
        {
    
            _userService = userService;
        }
        [HttpGet]
        public IActionResult Index()
        {
    
            return Ok(_userService.GetName("Test"));
        }
    }

Attribute auto Injection

Constructor injection is supported by default , If attribute injection is required , Compare constructor Injection , Attribute injection is added more **PropertiesAutowired() ** function

Be careful ： Property injection remember to change the access modifier of the property to the one accessible by the registered class , Otherwise, the injection will fail .

If not public An empty reference will be thrown .
The reason is probably Controller By Mvc Module managed , be not in IOC In container , So in Controller Not available in Autofac Injected instance .

//  Solve the above problems , stay  Startup  Of  ConfigureServices  Add the following code at the bottom of the method ：
//  Use  ServiceBasedControllerActivator  Replace  DefaultControllerActivator; // Controller  The default is a  Mvc  Module managed , be not in  Ioc  In the container . After replacement , Will be placed  Ioc  In the container . 
services.Replace(ServiceDescriptor.Transient<IControllerActivator, ServiceBasedControllerActivator>());
//  And then back to our  AutofacModuleRegister  Inject  Controller：
builder.RegisterTypes(GetAssemblyTypes<Startup>(type => typeof(ControllerBase).IsAssignableFrom(type)))                 .PropertiesAutowired();