c# - 实体类型需要在 EF Core 2.0 中定义主键

Question

我正在将带有 EF Core 项目的 ASP.NET Core 1.1 升级到 ASP.NET Core 2.0。

我有以下以前有效的实体和配置:

  public class Ebook {    
    public Int32 Id { get; set; }
    public String Title { get; set; }     
    public virtual ICollection<EbookFile> EbookFiles { get; set; } = new List<EbookFile>();    
  }

  public class EbookFile {        
    public Int32 EbookId { get; set; }
    public Int32 FileId { get; set; }    
    public virtual Ebook Ebook { get; set; }
    public virtual File File { get; set; }    
  }

  public class File {
    public Int32 Id { get; set; }
    public Byte[] Content { get; set; } 
    public virtual ICollection<EbookFile> EbookFiles { get; set; } = new List<EbookFile>();
  }

配置是:

builder.Entity<Ebook>(b => {
  b.ToTable("Ebooks");
  b.HasKey(x => x.Id);
  b.Property(x => x.Id).ValueGeneratedOnAddOrUpdate().UseSqlServerIdentityColumn();
  b.Property(x => x.Title).IsRequired(true).HasMaxLength(200);
  b.HasIndex(x => x.Title).IsUnique();
});

builder.Entity<EbookFile>(b => {
  b.ToTable("EbookFiles");
  b.HasKey(x => new { x.EbookId, x.FileId });
  b.HasOne(x => x.Ebook).WithMany(x => x.EbookFiles).HasForeignKey(x => x.EbookId).IsRequired(true).OnDelete(DeleteBehavior.Cascade);
  b.HasOne(x => x.File).WithMany(x => x.EbookFiles).HasForeignKey(x => x.FileId).IsRequired(true).OnDelete(DeleteBehavior.Cascade);
});

builder.Entity<File>(b => {
  b.ToTable("Files");
  b.HasKey(x => x.Id);
  b.Property(x => x.Id).UseSqlServerIdentityColumn();
  b.Property(x => x.Content).IsRequired(false);
});

在我的 Context 类中，我有以下属性:

public DbSet<Ebook> Ebooks { get; set; }
public DbSet<EbookFile> EbookFiles { get; set; }
public DbSet<File> Files { get; set; }

当我运行它时出现错误:

The entity type 'EbookFile' requires a primary key to be defined.

我在这里错过了什么？ EF Core 2.0 有什么变化吗？

Answer 1

除 Ivan 的回答外，我想您了解标识列不需要 ValueGeneratedOnAddOrUpdate。

您可以使用脚手架生成代码，在我的例子中我使用 CatFactory，您可以在此链接中查看它:https://www.codeproject.com/Articles/1160615/Generating-Code-for-EF-Core-with-CatFactory

问候