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c# - System.TypeInitializationException：''Bid' 的类型初始化程序引发了异常。'

问题描述

我有一个服务层，目标框架设置为.NET Standard 2.0. 一些服务使用DbContext来自EntityFrameWorkCore.

有两个 Web 项目使用此服务层：

该Core项目使用这样的依赖注入（缩短）：

public void ConfigureServices(IServiceCollection services)
{
    var json = File.ReadAllText("appsettings.json");
    var settings = JsonConvert.DeserializeObject<Settings>(json);
    services.AddScoped(provider => new CompetitorContext(settings.ConnectionStrings.Web));
    services.AddScoped<ICompetitorService, CompetitorService>();
}

该MVC项目通过 Unity 使用依赖注入，如下所示（缩短）：

public static void RegisterComponents()
{
    _container = new UnityContainer();

    var settings = 
        JsonConvert.DeserializeObject<Settings>(
            File.ReadAllText(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, 
            @"appsettings.json")));

    _container.RegisterInstance(typeof(CompetitorContext), new CompetitorContext(settings.ConnectionStrings.Web));
    _container.RegisterType<ICompetitorService, CompetitorService>();

    DependencyResolver.SetResolver(new UnityDependencyResolver(_container));
}

当调用调用CompetitorContext（继承自DbContext）的服务方法之一时，它在项目中工作正常，Core但在MVC项目中我收到此错误：

System.TypeInitializationException
  HResult=0x80131534
  Message=The type initializer for 'Bid' threw an exception.
  Source=<Cannot evaluate the exception source>
  StackTrace:
<Cannot evaluate the exception stack trace>

  This exception was originally thrown at this call stack:
    Bid.internalInitialize()
    Bid.Bid()

Inner Exception 1:
EntryPointNotFoundException: Unable to find an entry point named 'DllBidEntryPoint' in DLL 'System.Data.dll'.

其他不使用的服务EntityFrameWorkCore工作正常，所以我认为问题在于与项目EntityFrameWorkCore一起使用，.NET MVC 4.6.2但我不确定。

此异常的问题可能是什么，或者我如何才能找到更多信息？

已编辑CompetitorService：

public class CompetitorService : ICompetitorService
    {
        private readonly CompetitorContext _ctx;

        public CompetitorService(CompetitorContext ctx)
        {
            _ctx = ctx;
        }

        public IList<CompetitorModel> GetAll()
        {
           return _ctx.Competitors.OrderBy(c => c.ID).ToList();
        }

        public CompetitorModel GetById(int id)
        {
            return this.GetAll().Where(c => c.ID == id).First();
        }

        public CompetitorModel GetByCompetitorKey(string competitorKey)
        {
            return this.GetAll().Where(c => c.CompetitorKey == competitorKey).FirstOrDefault();
        }
    }

CompetitorContext: _

public class CompetitorContext : DbContext
    {
        public DbSet<CompetitorModel> Competitors { get; set; }

        public CompetitorContext(string connectionString) :
            base(SqlServerDbContextOptionsExtensions.UseSqlServer(new DbContextOptionsBuilder(), connectionString).Options)
        {
        }
    }

CompetitorModel: _

[Table("vw_competitors")]
    public class CompetitorModel
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.None)]
        public int ID { get; set; }
        public string CompetitorKey { get; set; }
        public string Name { get; set; }
        public string ShortName { get; set; }
        public string Experience { get; set; }
        public string BBB_Rating { get; set; }
        public string BBB_URL { get; set; }
        public string BBB_Complaints { get; set; }
        public string BBB_Accredited { get; set; }
        public string TrustPilot_URL { get; set; }
        public string TrustPilot_Rating { get; set; }
        public string TrustPilot_Reviews { get; set; }
        public string RipoffReport_Complaints { get; set; }
        public string MoneyBackGuarantee { get; set; }
        public DateTime LastUpdated { get; set; }
    }

注意：引用的Bid类不是我的数据模型，我也不了解它

标签： c#asp.net-mvc.net-4.6.2entity-framework-core-3.0

解决方案

我们遇到了这个问题，并通过将 EF 核心更改为 EF 6.4.4 来解决它可能是您有这样的问题，需要更改或降级您的 EF 版本（如果您使用 EF）

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