nhibernate - NHibernate IUserType将可为空的DateTime转换为DB非空值

Question

我有旧版数据库，存储的日期表示无日期为9999-21-31，
列Till_Date的类型为DateTime not-null="true"。

在应用程序中，我要构建持久化类，将no-date表示为null，
所以我在C＃// public DateTime中使用了可为空的DateTime？ TillDate {获取；组; }

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

但似乎NHibernate不会在我的IUserType上调用SafeNullGet，SafeNullSet
当实体值为null且报告为null时，用于非null列。

我试图通过将列映射为not-null =“ false”来绕过它
（仅更改了映射文件，而不更改了数据库）
但是它仍然没有帮助，只是现在它尝试将null值插入数据库并获取ADOException。

是否知道NHibernate不支持将null转换为非null值的IUseType？

//实施所需的修复程序！！！

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; }
        }
    }
}

//带有修复程序的最终实现。

//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

您实施Equals时可能会出现问题。 NHibernate使用Equals来确定是否需要获取或设置该值。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转换为DateTime?。您实施的Equals看起来不错。