EF CORE - 创建一对多地图

Posted 2023-03-17

【中文标题】EF CORE - 创建一对多地图

【英文标题】：EF CORE - Create one-to-many map

【发布时间】：2020-12-16 20:32:00

【问题描述】：

我正在尝试创建一个一对多的地图，我尝试了很多方法来做到这一点，但我还没有弄清楚：/

我有 2 个实体，Wallet 和 Transfer，我想在 Transfer 中添加一个 FK WalletId，所以一次转账只有一个钱包，但一个钱包可以关联多个转账。

Wallet.cs -

public class Wallet
    

        public int Id  get; private set; 
        public decimal Balance  get; private set; 
    

Transfer.cs -

public class Transfer
    
        #region Properties
        public int Id  get; private set; 
        public decimal Value  get; private set; 
        public DateTime? TransferDate  get; private set; 
        public DateTime RegisterDate  get; private set; 
        public ETransferType TransferType  get; private set; 
    

WalletMap.cs -

public class WalletMap : IEntityTypeConfiguration<Wallet>
    
        public void Configure(EntityTypeBuilder<Wallet> builder)
        
            builder.HasKey(x => x.Id);
            builder.Property(x => x.Balance).HasColumnType("Money").IsRequired();
        
    

TransferMap.cs -

public class TransferMap : IEntityTypeConfiguration<Transfer>
    
        public void Configure(EntityTypeBuilder<Transfer> builder)
        
            builder.HasKey(x => x.Id);
            builder.Property(x => x.Value).HasColumnType("Money").IsRequired();
            builder.Property(x => x.TransferDate);
            builder.Property(x => x.RegisterDate).IsRequired();
            builder.Property(x => x.TransferType).IsRequired();
        
    

【参考方案1】：

添加foreign key 和navigation property：

public class Wallet

    public int Id  get; set; 
    public decimal Balance  get; set; 
    public virtual ICollection<Transfer> Transfers  get; set;  // Navigation Property


public class Transfer

    pubic int Id  get; private set; 
    public decimal Value  get; private set; 
    public Datetime? TransferDate  get; private set; 
    //.....Remaining properties
    public int WalletId  get; set;   //Foreign Key
    public virtual Wallet Wallet  get; set;   //Reference Navigation

这将添加所需的foreign key 和navigation properties。

//using fluent api
protected override void OnModelCreating(ModelBuilder modelBuilder)

    modelBuilder.Entity<Transfer>().HasOne(x => x.Wallet)
        .WithMany(x => x.Transfers)
        .HasForeignKey(x => x.WalletId);
    modelBuilder.Entity<Wallet>.HasMany(x => x.Transfers)
        .WithOne();

【参考方案2】：

到 Wallet.cs 添加：

public virtual ICollection<Transfer> Tranfers  get; set; 

到 Transfer.cs 添加：

public virtual Wallet Wallet  get; set; 

在您的配置块中添加 TransferMap.cs：

builder.HasRequired(x => x.Wallet).WithMany(x => x.Transfers).Map(x => x.MapKey("WalletId")).WillCascadeOnDelete();

如果您没有在数据库中配置级联删除，您可以删除 WillCascadeOnDelete()。这假设您已经在数据库的 Transfers 表中定义了 WalletId。