asp.net-core - 构造函数是不明确的错误.NET Core Web API

Question

我是 Web API 的新手。在我的 .NET Core 3.1 web api 中，我定义了 3 个相信重载的构造函数。

[Route("api/[controller]")]
[ApiController]
public class KipController : ControllerBase
{
    private readonly IConfiguration _configuration;
    private readonly IMapper _mapper;
    private readonly dbLNePMODev1Context _context;
    public KipController(IConfiguration configuration)
    {
        _configuration = configuration;
    }
    public KipController(IMapper mapper)
    {
        _mapper = mapper;
    }

    public KipController(dbLNePMODev1Context context)
    {
        _context = context;
    }
    ......

但是在执行应用程序时，它会说以下错误

System.AggregateException HResult=0x80131500 Message=Some services are not able to be constructed (Error while validating the service descriptor 'ServiceType: epmoAPI.Models.dbLNePMODev1Context Lifetime: Scoped ImplementationType: epmoAPI.Models.dbLNePMODev1Context': Unable to activate type 'epmoAPI.Models.dbLNePMODev1Context'. The following constructors are ambiguous: Void .ctor(Microsoft.EntityFrameworkCore.DbContextOptions) Void .ctor(Microsoft.EntityFrameworkCore.DbContextOptions1[epmoAPI.Models.dbLNePMODev1Context]))
Source=Microsoft.Extensions.DependencyInjection StackTrace: at
Microsoft.Extensions.DependencyInjection.ServiceProvider..ctor(IEnumerable1 serviceDescriptors, ServiceProviderOptions options) at Microsoft.Extensions.DependencyInjection.ServiceCollectionContainerBuilderExtensions.BuildServiceProvider(IServiceCollection services, ServiceProviderOptions options) at Microsoft.Extensions.DependencyInjection.DefaultServiceProviderFactory.CreateServiceProvider(IServiceCollection containerBuilder) at Microsoft.Extensions.Hosting.Internal.ServiceFactoryAdapter`1.CreateServiceProvider(Object containerBuilder) at Microsoft.Extensions.Hosting.HostBuilder.CreateServiceProvider() at Microsoft.Extensions.Hosting.HostBuilder.Build() at epmoAPI.Program.Main(String[] args) in C:\Projects\Enterprise PMO\ePMOHub\epmoAPI\Program.cs:line 16

This exception was originally thrown at this call stack: [External Code]

Inner Exception 1: InvalidOperationException: Error while validating the service descriptor 'ServiceType: epmoAPI.Models.dbLNePMODev1Context Lifetime: Scoped ImplementationType: epmoAPI.Models.dbLNePMODev1Context': Unable to activate type 'epmoAPI.Models.dbLNePMODev1Context'. The following constructors are ambiguous: Void .ctor(Microsoft.EntityFrameworkCore.DbContextOptions) Void .ctor(Microsoft.EntityFrameworkCore.DbContextOptions`1[epmoAPI.Models.dbLNePMODev1Context])

Inner Exception 2: InvalidOperationException: Unable to activate type 'epmoAPI.Models.dbLNePMODev1Context'. The following constructors are ambiguous: Void .ctor(Microsoft.EntityFrameworkCore.DbContextOptions) Void .ctor(Microsoft.EntityFrameworkCore.DbContextOptions`1[epmoAPI.Models.dbLNePMODev1Context])

请帮我。我不知道我的代码有什么问题

Answer 1

您的 IConfiguration (可能 IMapper )使用依赖注入(inject)，而 dbLNePMODev1Context才不是。这就是 ASP.NET Core 无法实例化它的原因。

更清洁的解决方案:

public KipController(IConfiguration configuration = null, IMapper mapper = null, dbLNePMODev1Context context = null)
{
    _configuration = configuration;
    _mapper = mapper;
    _context = context;
}