C# 未配置任何数据库提供程序。身份与EF7

这与其他问题不同

运行所选代码生成器时出错：
'未配置任何数据库提供程序。在设置服务时，通过覆盖DbContext类或AddDbContext方法中的OnConfigurang来配置数据库提供程序。“

将另一个数据库添加到我的项目时出现此错误。在此之前，我的项目与ASP.NET Identity 3配合得很好

现在我有两个数据库，一个自定义数据库：

public class ShopDbContext : DbContext
{
    public DbSet<Category> Categories { get; set; }
    public DbSet<Product> Products { get; set; }
    public DbSet<Producer> Producers { get; set; } 

    public ShopDbContext(DbContextOptions<ShopDbContext> options) : base (options)
    {
        Database.EnsureCreated();
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        // Follow the default behaviour of SqlServer for Identity Columns (Auto Increment)
        modelBuilder.ForSqlServerUseIdentityColumns();
    }
}

编辑2:

如果我将

UsersDbContext

更改为同时覆盖

onconfigurang

方法，它实际上会从那里创建数据库并工作（即使我没有从

Startup.cs

中删除行，并且应该这样做：

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    base.OnConfiguring(optionsBuilder);
    optionsBuilder.UseSqlServer(
        "Server=(localdb)\\mssqllocaldb;Database=DigitalShop_Identity;Trusted_Connection=True;MultipleActiveResultSets=true");
}

现在的问题是为什么从

Startup.cs

设置连接字符串不起作用？

编辑3:

---

在调试

UsersDbContext

的过程中，我注意到

onconfigurang

方法在构造函数之前运行！我想这就是为什么它从不执行

Database.EnsureCreated（）

并因此引发异常。这怎么可能呢？？？

请添加错误并显示IdentityDbContext。@DenisBubnov显示它？对不起IdentityDbContext。我指的是一条消息。堆栈跟踪-很好，但什么是错误消息？@DenisBubnov，这个问题的标题是错误消息！不是我。我跟踪了问题。我没有不要使用EF7，我对这个问题感兴趣。我投你一票

public void ConfigureServices(IServiceCollection services)
{
    // Add framework services.
    services.AddEntityFramework().AddSqlServer()
        .AddDbContext<UsersDbContext>(options =>
            options.UseSqlServer(Configuration["DatabaseConnections:Identity"]))
        .AddDbContext<ShopDbContext>(options =>
            options.UseSqlServer(Configuration["DatabaseConnections:Shop"]));

    services.AddIdentity<ApplicationUser, IdentityRole>()
        .AddEntityFrameworkStores<UsersDbContext>()
        .AddDefaultTokenProviders();

    services.AddMvc();

    // IoC Container
    // Add application services.
    services.AddTransient<IEmailSender, AuthMessageSender>();
    services.AddTransient<ISmsSender, AuthMessageSender>();
    services.AddTransient<UsersDbContext>();
    services.AddTransient<ShopDbContext>();
}

Microsoft.Data.Entity.Internal.DatabaseProviderSelector.SelectServices(ServiceProviderSource providerSource)
Microsoft.Data.Entity.Internal.DbContextServices.<>c__DisplayClass6_0.<Initialize>b__0()
Microsoft.Data.Entity.Internal.LazyRef`1.get_Value()
Microsoft.Data.Entity.Internal.DbContextServices.get_DatabaseProviderServices()
Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.GetProviderServices(IServiceProvider serviceProvider)
Microsoft.Extensions.DependencyInjection.EntityFrameworkServiceCollectionExtensions.<>c.<AddEntityFramework>b__0_11(IServiceProvider p)
Microsoft.Extensions.DependencyInjection.ServiceLookup.FactoryService.Invoke(ServiceProvider provider)
Microsoft.Extensions.DependencyInjection.ServiceProvider.ScopedCallSite.Invoke(ServiceProvider provider)
Microsoft.Extensions.DependencyInjection.ServiceProvider.<>c__DisplayClass12_0.<RealizeService>b__0(ServiceProvider provider)
Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType)
Microsoft.Extensions.DependencyInjection.ServiceProviderExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
Microsoft.Extensions.DependencyInjection.ServiceProviderExtensions.GetRequiredService[T](IServiceProvider provider)
Microsoft.Data.Entity.Infrastructure.AccessorExtensions.GetService[TService](IInfrastructure`1 accessor)
Microsoft.Data.Entity.Infrastructure.DatabaseFacade.EnsureCreated()
DigitalShop.Models.Db.UsersDbContext..ctor() in UsersDbContext.cs
namespace DigitalShop.Models.Db
{
    public class UsersDbContext : IdentityDbContext<ApplicationUser>
    {
        public UsersDbContext()
        {
            Database.EnsureCreated(); // <-- Error
        }
        protected override void OnModelCreating(ModelBuilder builder)
        {
            base.OnModelCreating(builder);
            // Customize the ASP.NET Identity model and override the defaults if needed.
--- End of stack trace from previous location where exception was thrown ---

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    base.OnConfiguring(optionsBuilder);
    optionsBuilder.UseSqlServer(
        "Server=(localdb)\\mssqllocaldb;Database=DigitalShop_Identity;Trusted_Connection=True;MultipleActiveResultSets=true");
}