Question

我有遗留数据库存储日期，意味着无日期为9999-21-31，列Till_Date的类型为DateTime not-null="true"。

在应用程序中

我想构建表示no-date为null的持久化类，所以我在C＃// public DateTime中使用了可以为空的DateTime？ TillDate {get;组; }

我创建了IUserType，它知道将实体空值转换为DB 9999-12-31

但似乎NHibernate没有在我的IUserType上调用SafeNullGet，SafeNullSet 当实体值为null时，报告null用于非空列。

我尝试通过将列映射为not-null =“false”来绕过它（仅更改了映射文件，而不是DB）但它仍然没有帮助，只是现在它尝试将空值插入数据库并获取ADOException。

知道NHibernate是否支持将null转换为非空值的IUseType？

//在必要的修复之前实施!!!

public class NullableDateTimeToNotNullUserType : IUserType
{
        private static readonly DateTime MaxDate = new DateTime(9999, 12, 31);

        public new bool Equals(object x, object y)
        {                                                   //This didn't work as well
            if (ReferenceEquals(x, y)) return true; //if(x == null && y == null) return false;

            if (x == null || y == null) return false;

            return x.Equals(y);
        }

        public int GetHashCode(object x)
        {
            return x == null ? 0 : x.GetHashCode();
        }

        public object NullSafeGet(IDataReader rs, string[] names, object owner)
        {
            var value = rs.GetDateTime(rs.GetOrdinal(names[0]));

            return (value == MaxDate)? null : value;
        }

        public void NullSafeSet(IDbCommand cmd, object value, int index)
        {
            var dateValue = (DateTime?)value;

            var dbValue = (dateValue.HasValue) ? dateValue.Value : MaxDate;

            ((IDataParameter)cmd.Parameters[index]).Value = dbValue;
        }

        public object DeepCopy(object value)
        {
            return value;
        }

        public object Replace(object original, object target, object owner)
        {
            return original;
        }

        public object Assemble(object cached, object owner)
        {
            return cached;
        }

        public object Disassemble(object value)
        {
            return value;
        }

        public SqlType[] SqlTypes
        {
            get { return new[] { NHibernateUtil.DateTime.SqlType }; }
        }

        public Type ReturnedType
        {
            get { return typeof(DateTime?); }
        }

        public bool IsMutable
        {
            get { return false; }
        }
    }
}

//使用修补程序进行最终实施。

//Make the column mapping in hbm.xml not-null="false" even if in DB null not allowed.
//Make sure the class mapping in xml doesn't have dynamic-insert="true"

public class NullableDateTimeToNotNullUserType : IUserType
{
        private static readonly DateTime MaxDate = new DateTime(9999, 12, 31);

        public new bool Equals(object x, object y)
        {                                                   //This didn't work as well
            if (ReferenceEquals(x, y)) return true; //if(x == null && y == null) return false;

            if (x == null || y == null) return false;

            return x.Equals(y);
        }

        public int GetHashCode(object x)
        {
            return x == null ? 0 : x.GetHashCode();
        }

        public object NullSafeGet(IDataReader rs, string[] names, object owner)
        {
            var value = NHibernateUtil.Date.NullSafeGet(rs, names[0]);

            return (value == MaxDate)? default(DateTime?) : value;
        }

        public void NullSafeSet(IDbCommand cmd, object value, int index)
        {
            var dateValue = (DateTime?)value;

            var dbValue = (dateValue.HasValue) ? dateValue.Value : MaxDate;

            NHibernateUtil.Date.NullSafeSet(cmd, valueToSet, index);
        }

        public object DeepCopy(object value)
        {
            return value;
        }

        public object Replace(object original, object target, object owner)
        {
            return original;
        }

        public object Assemble(object cached, object owner)
        {
            return cached;
        }

        public object Disassemble(object value)
        {
            return value;
        }

        public SqlType[] SqlTypes
        {
            get { return new[] { NHibernateUtil.DateTime.SqlType }; }
        }

        public Type ReturnedType
        {
            get { return typeof(DateTime?); }
        }

        public bool IsMutable
        {
            get { return false; }
        }
    }
}

Answer 1

问题可能出在Equals的实施中。 NHibernate使用Equals来确定它是否需要获取或设置值。请发布您的IUserType实现。

编辑：好的，我想我看到了问题。试试这个：

public object NullSafeGet(IDataReader rs, string[] names, object owner)
{
    var value = NHibernateUtil.Date.NullSafeGet(rs, names[0]);
    return (value == MaxDate) ? null : value;
}

public void NullSafeSet(IDbCommand cmd, object value, int index)
{
    var dateValue = (DateTime?)value;
    var dbValue = (dateValue.HasValue) ? dateValue.Value : MaxDate;
    NHibernateUtil.Date.NullSafeSet(cmd, valueToSet, index);
}

NullSafeGet可能还需要将返回值强制转换为DateTime？。你的Equals实现看起来是正确的。

NHibernate IUserType将可空的DateTime转换为DB非null值

1 个答案: