N-Hibernate中的长字符串与Oracle导致错误 [英] Long strings in N-Hibernate with Oracle cause error

问题描述

下面是我的对象类

  public class UserFieldEvent 
 {
 public virtual int Id {get;组; } 
 public virtual UserFieldBase UserField {get;组; } 
 public virtual EventType EventType {get;组; } 
 public virtual string EventScript {get;组; } 
} 
  

EventScript的长度可以从0到4000.
在数据库中，我为EventScript创建了一个CLOB类型的列。

下面是我的映射类：

 public UserFieldEventMap（）
 {
表（TBLDS_USERFIELDEVENT）; 
 Id（x => x.Id）.GeneratedBy.Sequence（SEQDS_USERFIELDEVENT）; 
 Map（x => x.EventType）.CustomType< EventType>（）; 
 Map（x => x.EventScript）.CustomSqlType（CLOB）; 
引用（x => x.UserField）.Column（USERFIELDBASEID）; 
 
 
 
 
 
 $ b现在每当EventScript的长度大于2000时，我都会收到错误ORA -01461：只能绑定LONG值才能插入到LONG列中。同时将对象保存到数据库中。任何人都可以提供帮助。 
 
解决方案
这是.NET提供的 System.Data .OracleClient.OracleConnection 驱动程序。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（引用自： http://thebasilet.blogspot.be/2009/07/nhibernate-oracle-clobs.html  a>）。
 
 pre $ public $ CustomOracleDriver：OracleClientDriver 
 {
 protected override void InitializeParameter（System.Data .dbbDataParameter dbParam，字符串名称，SqlType sqlType）
 {
 base.InitializeParameter（dbParam，name，sqlType）; 
 
 
 // System.Data.OracleClient.dll驱动程序生成一个ORA-01461异常，因为
 //驱动程序错误地推断了正在保存的字符串的列类型，
 //尝试强制服务器将LONG值更新为CLOB / NCLOB列类型。 
 //不正确行为的原因更加模糊，只有满足以下所有条件时才会发生
 // //。 
 // 1.）IDbDataParameter.Value =（字符串，其长度：4000>长度> 2000）
 // 2.）IDbDataParameter.DbType = DbType.String 
 // 3。 ）DB列的类型是NCLOB / CLOB 
 
 //上面是NHibernate的默认行为.OracleClientDriver 
 //所以我们使用内建的StringClobSqlType来告诉驱动程序使用NClob Oracle类型
 //这对于两个NCLOB / CLOB都没有问题。 
 //映射文件必须更新为使用StringClob作为属性类型
 //请参阅：http://thebasilet.blogspot.be/2009/07/nhibernate-oracle-clobs.html 
（if（sqlType is StringClobSqlType））
 {
（（OracleParameter）dbParam）.OracleType = OracleType.NClob; 
 
 
 
 
 
 
你需要更新你的 SessionFactory 来使用这个驱动，以及更新你的clob映射来使用 StringClob 自定义类型
  Map（x => x.EventType）.CustomSqlType（Clob）。CustomType（StringClob）; 
  
 
I am using oracle as db and fluent Nhibernate for mapping.


Below is my Object Class
 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; }
    }
The length of property EventScript can be from 0 to 4000.
In the database I made the column type for EventScript a CLOB.

Below is my mapping Class: 
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");
        }
Now whenever the length of EventScript is greater than 2000 I get the error "ORA-01461: can bind a LONG value only for insert into a LONG column ." while saving the object into database. Can anyone help on this.
解决方案
This is a known issue with the .NET provided System.Data.OracleClient.OracleConnection driver.  The fix is either to use the Oracle provided ODP.net client Oracle.DataAccess.Client.OracleConnection (see: http://nuget.org/packages/odp.net.x86/) or use the following workaround (referenced from: 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;
        }
    }
}
You need to update your SessionFactory to use this driver, as well as update any of your clob mappings to use StringClob custom type
Map(x => x.EventType).CustomSqlType("Clob").CustomType("StringClob");


                        
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