asp.net-core - Entity Framework Core 无法添加迁移

Question

执行dotnet ef add migration InitialMigration给出此错误的命令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ConfigureServices在 Startup 类上的方法如下：

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

VegaContext类是：

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

部分csproj文件是：

<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

如果您的代码正是您发布的内容，那么解决方案非常简单。只需公开您的 DbContext 构造函数，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; }
}