如何在 asp.net-core 中使用代码优先迁移删除唯一约束

Question

我有一个项目，我添加了一个带有外键的初始迁移，如下所示：

 public class ApplicationUser : IdentityUser 
 {
  public string RegistrarId { get; set; }
 
  [ForeignKey("RegistrarId")]
  public virtual ApplicationUser Registrar { get; set; }

 }

但是，我意识到当我运行代码优先迁移时，它会自动在 Registrar 列上创建一个唯一索引，这违背了我的意愿。

 migrationBuilder.CreateIndex(
            name: "IX_AspNetUsers_RegistrarId",
            table: "AspNetUsers",
            column: "RegistrarId",
            unique: true,
            filter: "[RegistrarId] IS NOT NULL");

我的问题是，有没有办法修改我的类以通过另一个迁移删除此约束。

下面是我对 ApplicationUser 实体 onModelCreating 所拥有的

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

        modelBuilder.Entity<ApplicationUser>(b =>
        {
            // Each User can have many UserClaims
            b.HasMany(e => e.Claims)
                .WithOne(e => e.User)
                .HasForeignKey(uc => uc.UserId)
                .IsRequired();

            // Each User can have many UserLogins
            b.HasMany(e => e.Logins)
                .WithOne(e => e.User)
                .HasForeignKey(ul => ul.UserId)
                .IsRequired();

            // Each User can have many UserTokens
            b.HasMany(e => e.Tokens)
                .WithOne(e => e.User)
                .HasForeignKey(ut => ut.UserId)
                .IsRequired();

            // Each User can have many entries in the UserRole join table
            b.HasMany(e => e.UserRoles)
                .WithOne(e => e.User)
                .HasForeignKey(ur => ur.UserId)
                .IsRequired();

            b.HasIndex(e => e.Email)
                .IsUnique();             
        });

我的应用程序在 ASP.NET-Core 3.1 上，带有 EF-Core 3.1 和 SQLServer

请帮忙谢谢

Answer 1

您很可能在OnModelCreating配置了唯一索引。 如果这样做，只需将其翻转为 false。

protected override void OnModelCreating(ModelBuilder builder)
{
    builder.Entity<ApplicationUser>()
        .HasIndex(x => x.RegistrarId)
        .IsUnique(false);

    base.OnModelCreating(builder);
}

它将生成“删除和创建”索引迁移，但没有唯一属性

protected override void Up(MigrationBuilder migrationBuilder)
{
    migrationBuilder.DropIndex(
        name: "IX_AspNetUsers_RegistrarId",
        table: "AspNetUsers");

    migrationBuilder.CreateIndex(
        name: "IX_AspNetUsers_RegistrarId",
        table: "AspNetUsers",
        column: "RegistrarId");
}