c# - .Net Core 一对多关系导航不起作用

Question

我正在将 .Net Framework 网站转换为 .Net Core 网站。

当我放置一个断点并深入到Company 数据时，我看到了关系，但我没有看到任何Server 数据。我已检查 SQL Server 并验证我确实有一个 Company 和一个关联的 Server。

我有一个一对多关系反射(reflect)在 SQL Server 图中，如下所示:

Company 的一些实体类如下:

public class Company
{
    //
    [Required(ErrorMessage = "'Company Id' is required.")]
    public int CompanyId { get; set; }
    [Required(ErrorMessage = "'Company Short Name' is required."), MaxLength(12, ErrorMessage = "'CompanyShortName' must be 12 or less characters.")]
    public string CompanyShortName { get; set; }
    [Required(ErrorMessage = "'Company Name' is required."), MaxLength(80, ErrorMessage = "'CompanyName' must be 80 or less characters.")]
    public string CompanyName { get; set; }
    [MaxLength(80, ErrorMessage = "'Address' must be 80 or less characters.")]
    public string Address { get; set; }
    ...
    //
    public ICollection<Server> Servers { get; } = new List<Server>();
    public ICollection<ApplicationUser> Users { get; } = new List<ApplicationUser>();
    public ICollection<EmailTemplate> EmailTemplates { get; } = new List<EmailTemplate>();
    //
}

Server的部分实体类如下:

[Table("Servers")]
public class Server : IServer
{
    //
    [Required(ErrorMessage = "'Server Id' is required.")]
    public int ServerId { get; set; }
    [Required(ErrorMessage = "'Company Id' is required.")]
    public int CompanyId { get; set; }      // FK of the company that manages the server.
    [Required(ErrorMessage = "'Server Short Name' is required."),
        MinLength(6, ErrorMessage = "'Server Short Name' must be 6 or up to 12 characters."),
        MaxLength(12, ErrorMessage = "'Server Short Name' must be 12 or less characters.")]
    public string ServerShortName { get; set; }  // for login
    [Required(ErrorMessage = "'Server Name' is required."), MaxLength(80, ErrorMessage = "'Server Name' must be 80 or less characters.")]
    public string ServerName { get; set; }      // internal 
    ...
    //
    public virtual Company Company { get; set; }
    //
    public ICollection<ApplicationUserServer> UserServers { get; }
        = new List<ApplicationUserServer>();
    public ICollection<NetworkLog> NetworkLogs { get; }
        = new List<NetworkLog>();
    public ICollection<Incident> Incidents { get; }
        = new List<Incident>();
    //
}

在数据库上下文中，OnModelCreating 如下:

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        ...
        modelBuilder.Entity<Company>((item) =>
        {
            item.HasKey(c => c.CompanyId);
            item.HasMany(u => u.Servers).WithOne(s => s.Company).HasForeignKey(s => s.CompanyId);
            item.HasIndex(c => c.CompanyShortName).IsUnique()
                .HasName("Idx_Companies_ShortName");
        });
        //
        modelBuilder.Entity<Server>((item) =>
        {
            item.HasKey(s => s.ServerId);
            item.HasMany(u => u.UserServers).WithOne(u => u.Server).HasForeignKey(u => u.ServerId);
            item.HasOne(c => c.Company).WithMany(s => s.Servers)
                .HasForeignKey(s => s.CompanyId).OnDelete(DeleteBehavior.Restrict);
            // index
            item.HasIndex(s => s.ServerShortName).IsUnique()
                .HasName("Idx_AspNetServers_ShortName");
        });
        ...
    }

.Net Core 中的许多内容与我的 .Net Framework 版本不同，因此显然我不理解某些内容。随着我收集更多信息，我注意到其他缺失的导航数据。此外，我的内存测试工作正常，我可以看到导航 Server 数据。这是 GitHub 上的 .Net Framework 版本:

Net-Incident on GitHub

Answer 1

您必须在查询结果中包含这些关系

using (var context = new BloggingContext())
{
    var blogs = context.Blogs
        .Include(blog => blog.Posts)
        .ToList();
}

More info