实体框架错误：引入 FOREIGN KEY 约束指定 ON DELETE NO ACTION 或 ON UPDATE NO ACTION

Question

我正在尝试实现实体框架代码优先的方法，但出现错误：

引入 FOREIGN KEY 约束 表上的“FK_dbo.StateMasters_dbo.CountryMasters_CountryRefId” 'StateMasters' 可能会导致循环或多个级联路径。指定开 DELETE NO ACTION 或 ON UPDATE NO ACTION，或修改其他 FOREIGN KEY 约束。

这是我的 EF 代码。只需在数据库中插入记录。

领域类：

public class CountryMaster
{
    public CountryMaster()
    {
    }

    [Key]
    public int CountryCode { get; set; }

    [ConcurrencyCheck, Required, MaxLength(50), MinLength(2)]
    public string CountryName { get; set; }

    public ICollection<StateMaster> States { get; set; }
    public ICollection<CityMaster> Cities { get; set; }
}

public class StateMaster
{
    public StateMaster()
    {
    }

    [Key]
    public int StateCode { get; set; }

    public int CountryRefId { get; set; }

    [ForeignKey("CountryRefId")]
    public CountryMaster Country { get; set; }

    [ConcurrencyCheck, Required, MaxLength(50), MinLength(2)]
    public string StateName { get; set; }
    //  public ICollection<CityMaster> Cities { get; set; }
}

public class CityMaster
{
     public CityMaster()
     {
     }

     [Key]
     public int CityCode { get; set; }

     public int CountryRefId { get; set; }

     [ForeignKey("CountryRefId")]
     public CountryMaster Country { get; set; }

     public int StateRefId { get; set; }

     [ForeignKey("StateRefId")]
     public StateMaster State { get; set; }

     [ConcurrencyCheck, Required, MaxLength(50), MinLength(2)]
     public string CityName { get; set; }
}

存储库接口：

public interface I_COUNTRY_STATE_CITYRepository:IDisposable
{
    void InsertCountry(CountryMaster Country);
    void SaveCountry();
}

存储库实现：

public class COUNTRY_STATE_CITYRepository : IDisposable, I_COUNTRY_STATE_CITYRepository
{
    private COUNTRY_STATE_CITYContext context;

    public COUNTRY_STATE_CITYRepository(COUNTRY_STATE_CITYContext context)
    {
        this.context = context;
    }

    public void InsertCountry(CountryMaster Country)
    {
        context.Countries.Add(Country);
    }

    private bool disposed = false;

    protected virtual void Dispose(bool disposing)
    {
        if (!this.disposed)
        {
            if (disposing)
            {
                context.Dispose();
            }
        }

        this.disposed = true;
    }

    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    public void SaveCountry()
    {
         context.SaveChanges();
    }
}

上下文类：

public class COUNTRY_STATE_CITYContext: DbContext
{
     public COUNTRY_STATE_CITYContext() : base("ConnectionString")
     { }

     public DbSet<CountryMaster> Countries { get; set; }
     public DbSet<StateMaster> States { get; set; }
     public DbSet<CityMaster> Cities { get; set; }

     protected override void OnModelCreating(DbModelBuilder modelBuilder)
     {
         modelBuilder.Entity<CountryMaster>().HasMany(i => i.States).WithRequired().WillCascadeOnDelete(false);
     }
 }

C# 代码是简单地传递国家名称的值并插入数据库：

public partial class CheckCountryStateCity : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    { }

    protected void btnAdd_Click(object sender, EventArgs e)
    {
        using (var ctx = new COUNTRY_STATE_CITYContext())
        {
            COUNTRY_STATE_CITYRepository wr = new                  COUNTRY_STATE_CITYRepository(ctx);
            CountryMaster wt = new CountryMaster();

            wt.CountryName = "ABC";
            wr.InsertCountry(wt);
            wr.SaveCountry();
        }
    }
}

Answer 1

您在某些表中有带有外键的现有记录。因此，当您尝试删除此类数据时会导致错误。

解决方案： 如果要删除父记录删除中的引用数据，则应在数据库中提及级联删除。

或

您必须在删除引用记录时限制用户。