Entity Framework核心无法添加迁移

Question

执行 dotnet ef add migration InitialMigration 命令出现此错误 A suitable constructor for type 'Vega.Repository.VegaContext' could not be located. Ensure the type is concrete and services are registered for all parameters of a public constructor.

我的 ConfigureServices 启动方法 class 如下：

public void ConfigureServices(IServiceCollection services)
{            
   services.AddMvc();       
   services.AddScoped<IUnitOfWork, UnitOfWork>();
   var connectionString = Configuration.GetConnectionString("VegaConnection");
   services.AddDbContext<VegaContext>(options =>
            options.UseSqlServer(connectionString));
}

VegaContext class 是：

public class VegaContext : DbContext
{
    VegaContext(DbContextOptions<VegaContext> options):base(options)
    {}
    public DbSet<Make> Makes { get; set; }
}

csproj 文件的一部分是：

<ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.0.5" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.0.1" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.0.2" />
</ItemGroup>

<ItemGroup>
    <DotNetCliToolReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Tools" Version="2.0.2" />
    <DotNetCliToolReference Include="Microsoft.EntityFrameworkCore.Tools.DotNet" Version="2.0.1" />
</ItemGroup>

Answer 1

如果您的代码与您发布的代码完全相同，那么解决方案就非常简单。只需创建您的 DbContext-constructor public，一切都应该没问题：

public class VegaContext : DbContext
{
    public VegaContext(DbContextOptions<VegaContext> options):base(options) { }
    public DbSet<Make> Makes { get; set; }
}