找到了多个 DbContext

Question

我正在使用 AspCore 2 实现代码优先数据库。我有一个“DataContext.cs”，如下所示：

public class ApplicationUser : IdentityUser
{
    public string FirstName { get; set; }
    public string MiddelName { get; set; }
    public string LastName { get; set; }
    public bool IsActive { get; set; }
    public DateTime? DateAdded { get; set; }
}

public class DataContext : IdentityDbContext<ApplicationUser>
{
    public DataContext(DbContextOptions<DataContext> options) : base(options) {}

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

          //AspNetUsers -> User
        modelBuilder.Entity<ApplicationUser>()
            .ToTable("User");
        //AspNetRoles -> Role
        modelBuilder.Entity<IdentityRole>()
            .ToTable("Role");
        //AspNetUserRoles -> UserRole
        modelBuilder.Entity<IdentityUserRole>()
            .ToTable("UserRole");
        //AspNetUserClaims -> UserClaim
        modelBuilder.Entity<IdentityUserClaim>()
            .ToTable("UserClaim");
        //AspNetUserLogins -> UserLogin
        modelBuilder.Entity<IdentityUserLogin>()
            .ToTable("UserLogin");
    }
}

这在我的“startup.cs”中

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddDbContext<DataContext>(x => x.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseMvc();
    }
}

当我尝试运行 dotnet 迁移时，dotnet ef migrations add InitialCreate出现以下错误：

“找到了多个 DbContext。指定要使用的 DbContext。对 PowerShell 命令使用 '-Context' 参数，对 dotnet 命令使用 '--context' 参数。”

你能帮我把这个做对吗​​？谢谢！

Answer 1

看起来有几个类是从 DbContext 类继承而来的（可能来自某个 NuGet 包）。所以添加迁移

Add-Migration MyMigration -context DataContextName

Answer 2

请遵循此语法

Add-Migration [-Name] <String> [-OutputDir <String>] [-Context <String>] [-Project <String>] [-StartupProject <String>] [-Environment <String>] [<CommonParameters>]

在你的情况下，

add-migration MyMigration -Context DataContext

Answer 3

dotnet ef migrations add <your_migration_name> -c <your_context_class_name>

[--上下文| -C]

要使用的 DbContext 类。仅类名或使用命名空间完全限定。如果省略此选项，EF Core 将查找上下文类。如果有多个上下文类，则需要此选项。

来自https://learn.microsoft.com/en-us/ef/core/miscellaneous/cli/dotnet#common-options

Answer 4

update-database -Context YourContext