C# EF Core 2.2新迁移不断删除和重新创建种子数据

无论何时创建新迁移，出于某种原因，种子数据总是被删除并重新创建。我怎样才能防止这种情况发生

这似乎是EF Core 2.1中的一个bug，但应该在2.2中修复，但这个问题仍然存在

这是我的OnModelCreating：

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);
    Application application = new Application
    {
        Id = Guid.NewGuid().ToString(),
        Name = "APPONE",
        Description = "APPONE",
        TagColor = "#fb3640",
        IsActive = true,
        CreatedOn = DateTime.Now,
        UpdatedOn = DateTime.Now
    };

    User user = new User
    {
        Id = "223862af-978e-41a9-90ca-fda4b0f49c77",
        UserName = "system@managementstudio.com",
        NormalizedUserName = "SYSTEM@MANAGEMENTSTUDIO.COM",
        Email = "system@managementstudio.com",
        NormalizedEmail = "SYSTEM@MANAGEMENTSTUDIO.COM",
        SecurityStamp = "42032b8b-4581-46cf-8c56-a53e155176a3",
        PhoneNumber = "1234567890",
        FirstName = "System",
        LastName = "Administrator",
        ConcurrencyStamp = "8a75b8eb-01e6-4aff-b59b-849ad93cd28e",
        CreatedOn = Convert.ToDateTime("2020-04-16 19:22:09.546094"),
        UpdatedOn = Convert.ToDateTime("2020-04-16 19:22:09.546094"),
        PasswordHash = "AQAAAAEAACcQAAAAEATcP3mZf4Ok1uuUwpnG4v6ES3XJ4VsyiM3G9hhKgZNwen4Z3ke5DEIvK1acSJOhDQ==",
    };

    UserPasswordPolicy upp = new UserPasswordPolicy
    {
        Id = Guid.NewGuid().ToString(),
        IsPolicyActivated = false,
        RetentionDays = 0,
        TenantId = null,
        UserId = user.Id,
        CreatedOn = DateTime.Now,
    };

    Role role = new Role
    {
        Id = "d5e3f676-e489-479d-b739-8ea9a8483496",
        Name = "SystemAdministrator",
        NormalizedName = "SYSTEMADMINISTRATOR",
        ApplicationId = application.Id,
        Order = 1,
        ConcurrencyStamp = "ba953d0b-89dc-4550-9962-c9ba08a3980e",
    };

    Role role2 = new Role
    {
        Id = "225c067c-c703-419e-9fc9-8186ded506f8",
        Name = "Administrator",
        NormalizedName = "ADMINISTRATOR",
        ApplicationId = application.Id,
        Order = 2,
        ConcurrencyStamp = "a09ab67f-02d6-4910-8659-3385759d8036",
    };

    UserRole userRole = new UserRole
    {
        RoleId = role.Id,
        UserId = user.Id
    };

    SystemAdministrator systemAdministrator = new SystemAdministrator
    {
        Id = Guid.NewGuid().ToString(),
        UserId = user.Id,
        CreatedOn = DateTime.Now
    };

    //https://www.learnentityframeworkcore.com/migrations/seeding
    PasswordHasher<User> passwordHasher = new PasswordHasher<User>();
    user.PasswordHash = passwordHasher.HashPassword(user, "P@ssw0rd");

    modelBuilder.Entity<Application>().HasData(application);
    modelBuilder.Entity<User>().HasData(user);
    var rolesTable = modelBuilder.Entity<Role>().ToTable("Roles");
    var userRolesTable = modelBuilder.Entity<UserRole>().ToTable("UserRoles");
    var userClaimsTable = modelBuilder.Entity<IdentityUserClaim<string>>().ToTable("UserClaims");
    var usersTable = modelBuilder.Entity<User>().ToTable("Users");

    modelBuilder.Entity<Role>(builder =>
    {
        builder.Metadata.RemoveIndex(new[] { builder.Property(u => u.NormalizedName).Metadata });
    });
    modelBuilder.Entity<User>(builder =>
    {
        builder.Metadata.RemoveIndex(new[] { builder.Property(u => u.NormalizedUserName).Metadata });
    });
    modelBuilder.Entity<User>(builder =>
    {
        builder.Metadata.RemoveIndex(new[] { builder.Property(u => u.UserName).Metadata });
    });
    modelBuilder.Entity<User>(b =>
        b.HasIndex("NormalizedUserName", "TenantId").HasName("UserNameIndex").IsUnique());

    modelBuilder.Entity<Role>().HasData(role);
    modelBuilder.Entity<Role>().HasData(role2);
    modelBuilder.Entity<UserRole>().HasData(userRole);
    modelBuilder.Entity<UserPasswordPolicy>().HasData(upp);
    modelBuilder.Entity<SystemAdministrator>().HasData(systemAdministrator);

}

---

这是由于对ID使用了

Guid.NewGuid（）.ToString（）

。当EF为种子数据（将在每个迁移应用程序期间发生）时，它使用id确定是否应创建新实体或使用种子数据更新现有实体。由于id始终不同，因此它将始终创建而不是更新。如果希望更新，则需要使用静态值

protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.UpdateData(
                table: "UserPasswordPolicy",
                keyColumn: "Id",
                keyValue: "845c4aff-ed80-45c3-a5c3-7dba838e575b",
                column: "UpdatedOn",
                value: new DateTime(2020, 4, 21, 7, 9, 46, 923, DateTimeKind.Local).AddTicks(6432));

            migrationBuilder.UpdateData(
                table: "Users",
                keyColumn: "Id",
                keyValue: "223862af-978e-41a9-90ca-fda4b0f49c77",
                column: "PasswordHash",
                value: "AQAAAAEAACcQAAAAEATcP3mZf4Ok1uuUwpnG4v6ES3XJ4VsyiM3G9hhKgZNwen4Z3ke5DEIvK1acSJOhDQ==");
        }