Question

这是我第一次使用asp 5 \ core1而我在设置实体框架dbcontext时出现问题

我有一个带有我的对象的类库

public class Utilizador
    {
        public Utilizador()
        {

        }

        public int id { get; set; }
    }

然后我有一个Web Api项目，其中包含对我的类和上下文的引用

public class Context : DbContext
{
    public Context(DbContextOptions<Context> options)
        : base(options)
    {

    }

    public DbSet<Utilizador> Utilizadores { get; set; }

}

我的package.json就像实体框架一样

"dependencies": {
    "Microsoft.NETCore.App": {
      "version": "1.0.0-rc2-3002702",
      "type": "platform"
    },
    "Microsoft.AspNetCore.Mvc": "1.0.0-rc2-final",
    "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0-rc2-final",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0-rc2-final",
    "Microsoft.AspNetCore.Mvc.WebApiCompatShim": "1.0.0-rc2-final",
    "Microsoft.EntityFrameworkCore": "1.0.0-rc2-final",
    "Microsoft.EntityFrameworkCore.Tools":  "1.0.0-preview1-final" ,
    "Microsoft.EntityFrameworkCore.SqlServer": "1.0.0-rc2-final"
  },

  "tools": {
    "Microsoft.AspNetCore.Server.IISIntegration.Tools": {
      "version": "1.0.0-preview1-final",
      "imports": "portable-net45+win8+dnxcore50"
    },
    "Microsoft.EntityFrameworkCore.Tools": {
    "version": "1.0.0-preview1-final",
    "imports": [
      "portable-net45+win8+dnxcore50",
      "portable-net45+win8"
    ]
  }
  },

  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "dotnet5.6",
        "dnxcore50",
        "portable-net45+win8"
      ]
    }
  }

最后我的startup.cs

            public void ConfigureServices(IServiceCollection services)
    {
        // Add framework services.
        services.AddMvc();
      services.AddEntityFramework().AddEntityFrameworkSqlServer().AddDbContext<Context>(options => options.UseSqlServer(Configuration["ConnectionStrings:DefaultConnection"]));

    }

我使用了Add-Migrations命令，它创建了我的数据库和一个名为__MigrationsHistory的表，但没有为我的类创建任何表，所以我使用了Add-Migration＆＃34; mycontext＆＃34;一切都停止了工作，现在我每次尝试进行迁移时都会收到此错误：

System.ArgumentException: GenericArguments[0], 'WebApiSolution.Migrations.Context', on 'Microsoft.EntityFrameworkCore.Infrastructure.IDbContextFactory`1[TContext]' violates the constraint of type 'TContext'. ---> System.TypeLoadException: GenericArguments[0], 'WebApiSolution.Migrations.Context', on 'Microsoft.EntityFrameworkCore.Infrastructure.IDbContextFactory`1[TContext]' violates the constraint of type parameter 'TContext'.    at System.RuntimeTypeHandle.Instantiate(RuntimeTypeHandle handle, IntPtr* pInst, Int32 numGenericArgs, ObjectHandleOnStack type)
   at System.RuntimeTypeHandle.Instantiate(Type[] inst)
   at System.RuntimeType.MakeGenericType(Type[] instantiation)
   --- End of inner exception stack trace ---
    at System.RuntimeType.ValidateGenericArguments(MemberInfo definition, RuntimeType[] genericArguments, Exception e)
    at System.RuntimeType.MakeGenericType(Type[] instantiation)
    at Microsoft.EntityFrameworkCore.Design.DbContextOperations.FindContextFactory(Type contextType) 
    at Microsoft.EntityFrameworkCore.Design.DbContextOperations.FindContextTypes() 
   at Microsoft.EntityFrameworkCore.Design.DbContextOperations.FindContextType(String name)
   at Microsoft.EntityFrameworkCore.Design.DbContextOperations.CreateContext(String contextType)
   at Microsoft.EntityFrameworkCore.Design.MigrationsOperations.RemoveMigration(String contextType, Boolean force)
    at Microsoft.EntityFrameworkCore.Tools.Cli.MigrationsRemoveCommand.<>c__DisplayClass0_0.<Configure>b__0()
    at Microsoft.Extensions.CommandLineUtils.CommandLineApplication.Execute(String[] args) 
   at Microsoft.EntityFrameworkCore.Tools.Cli.Program.Main(String[] args)
 GenericArguments[0], 'WebApiSolution.Migrations.Context', on 'Microsoft.EntityFrameworkCore.Infrastructure.IDbContextFactory`1[TContext]' violates the constraint of type 'TContext'.

有人可以指出我正确的方向吗？我做错了什么，我在这里失踪了什么？

感谢

Answer 1

尝试将数据库初始值设定项添加到您的上下文中：

编辑：我的初步答案基于实体框架6. Database.EnsureCreated（）听起来可能是最新版本中的等效方法：

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

＆＃39; Microsoft.EntityFrameworkCore.Infrastructure.IDbContextFactory`1 [TContext]＆＃39;违反了类型参数的限制＆＃39; TContext＆＃39;

1 个答案: