C# Entity Framework 链表外键

Question

我想在数据库中保存一个 LinkedList 以便稍后处理，因此我得到了一个包含一个字段“Next”和一个字段“Previous”的模型。对于“create table”语句，它应该创建两个名为 PreviousId 和 NextId 的外键，但是当我在 SQLite Db 中看到 create 语句时，只有一个。

我已将参考添加到 OnModelcreating 方法，但似乎第二个被解释为第一个的重复。

我有以下模型要存储在数据库中：

public class BlockLink : BaseEntry
{
    [ForeignKey(nameof(PreviousId))]
    public ulong? PreviousId { get; set; }
    [ForeignKey(nameof(NextId))]
    public ulong? NextId { get; set; }

    public BlockLink Previous { get; set; }
    public int Current { get; set; }
    public BlockLink Next { get; set; }
    public Targets Target { get; set; }

    public BlockLink(Targets target) => Target = target;
}

这里是 OnModelCreating 方法中的关系：

            modelBuilder.Entity<BlockLink>()
           .HasOne(f => f.Next)
           .WithOne(f => f.Previous)
           .HasForeignKey(typeof(BlockLink), nameof(BlockLink.NextId));
        
        modelBuilder.Entity<BlockLink>()
           .HasOne(f => f.Previous)
           .WithOne(f => f.Next)
           .HasForeignKey(typeof(BlockLink), nameof(BlockLink.PreviousId));

这是创建语句：

CREATE TABLE "BlockList" (
"Id" INTEGER NOT NULL CONSTRAINT "PK_BlockList" PRIMARY KEY AUTOINCREMENT,
"PreviousId" INTEGER NULL,
"NextId" INTEGER NULL,
"Current" INTEGER NULL,
"Target" INTEGER NOT NULL,
"CreationTime" TEXT NOT NULL,
"LastUpdate" TEXT NOT NULL,
"Info" TEXT NULL,
CONSTRAINT "FK_BlockList_BlockList_PreviousId" FOREIGN KEY ("PreviousId") REFERENCES "BlockList" ("Id") ON DELETE RESTRICT)

Answer 1

我发现，其实并没有那么难。解决方案：

modelBuilder.Entity<BlockLink>()
    .HasOne(x => x.Next);
modelBuilder.Entity<BlockLink>()
    .HasOne(n => n.Previous);

public class BlockLink : BaseEntry
{ 
    public ulong? PreviousId { get; set; }
    public ulong? NextId { get; set; }

    [ForeignKey(nameof(PreviousId))]
    public BlockLink Previous { get; set; }
    public TX_BASE_Type Current { get; set; }

    [ForeignKey(nameof(NextId))]
    public BlockLink Next { get; set; }
    public Targets Target { get; set; }

    public BlockLink(Targets target) => Target = target;
}

C# Entity Framework 链表外键

C# Entity Framework LinkedList ForeignKeys

c#

sqlite

entity-framework

linked-list

foreign-keys