使用Oracle的N-Hibernate中的长字符串会导致错误
本文关键字:字符串 错误 Oracle N-Hibernate 使用 | 更新日期: 2023-09-27 18:19:32
我使用oracle作为数据库,使用fluent Nhibernate进行映射。
下面是我的对象类
public class UserFieldEvent
{
public virtual int Id { get; set; }
public virtual UserFieldBase UserField { get; set; }
public virtual EventType EventType { get; set; }
public virtual string EventScript { get; set; }
}
属性EventScript的长度可以在0到4000之间。在数据库中,我将EventScript的列类型设置为CLOB。
下面是我的映射类:
public UserFieldEventMap()
{
Table("TBLDS_USERFIELDEVENT");
Id(x => x.Id).GeneratedBy.Sequence("SEQDS_USERFIELDEVENT");
Map(x => x.EventType).CustomType<EventType>();
Map(x => x.EventScript).CustomSqlType("CLOB");
References(x => x.UserField).Column("USERFIELDBASEID");
}
现在,每当EventScript的长度大于2000时,我都会在将对象保存到数据库时收到错误"ORA-01461:can bind a LONG value only for insert into a LONG column"。有人能帮上忙吗。
这是.NET提供的System.Data.OracleClient.OracleConnection
驱动程序的已知问题。修复方法是使用Oracle提供的ODP.net客户端Oracle.DataAccess.Client.OracleConnection
(请参阅:http://nuget.org/packages/odp.net.x86/)或使用以下解决方法(参考自:http://thebasilet.blogspot.be/2009/07/nhibernate-oracle-clobs.html)。
public class CustomOracleDriver : OracleClientDriver
{
protected override void InitializeParameter(System.Data.IDbDataParameter dbParam, string name, SqlType sqlType)
{
base.InitializeParameter(dbParam, name, sqlType);
// System.Data.OracleClient.dll driver generates an ORA-01461 exception because
// the driver mistakenly infers the column type of the string being saved, and
// tries forcing the server to update a LONG value into a CLOB/NCLOB column type.
// The reason for the incorrect behavior is even more obscure and only happens
// when all the following conditions are met.
// 1.) IDbDataParameter.Value = (string whose length: 4000 > length > 2000 )
// 2.) IDbDataParameter.DbType = DbType.String
// 3.) DB Column is of type NCLOB/CLOB
// The above is the default behavior for NHibernate.OracleClientDriver
// So we use the built-in StringClobSqlType to tell the driver to use the NClob Oracle type
// This will work for both NCLOB/CLOBs without issues.
// Mapping file must be updated to use StringClob as the property type
// See: http://thebasilet.blogspot.be/2009/07/nhibernate-oracle-clobs.html
if ((sqlType is StringClobSqlType))
{
((OracleParameter)dbParam).OracleType = OracleType.NClob;
}
}
}
您需要更新SessionFactory
以使用此驱动程序,还需要更新任何clob映射以使用StringClob
自定义类型
Map(x => x.EventType).CustomSqlType("Clob").CustomType("StringClob");