Mapping clobs using Fluent NHibernate, Oracle 10g and OracleClientConfiguration.Oracle10 - nhibernate

Question

I've been trying to map a clob field using Fluent NHibernate 1.2.0.712 against Oracle 10g. I'm using System.Data provider as it's available by default and was trying to avoid adding reference to ODP.Net due to previous client issues.
However, when I try to insert entities with mapped clob properties, I get the error:
ORA-01461: can bind a LONG value only for insert into a LONG column
I've tried to fix this by using the below convention, and decorating the appropriate property with [StringLength(4000)]:
public class StringLengthConvention : AttributePropertyConvention<StringLengthAttribute>
{
protected override void Apply(StringLengthAttribute attribute, IPropertyInstance instance)
{
instance.Length(attribute.MaximumLength);
}
}
This didn't work.
Then I tried the below using "TEXT", "CLOB" and "clob" values. Neither worked:
public class plaparteMappingOverride : IAutoMappingOverride<plaparte>
{
public void Override(AutoMapping<plaparte> mapping)
{
Map(x => x.disposiciones).CustomSqlTypeIs("TEXT");
}
}
Does anyone have further suggestions for this fix other than adding ODP as the provider?

Answer 1

For future reference: this post perfectly describes what causes this error and how you can solve it.
ORA-01461: can bind a LONG value only for insert into a LONG column
This error is not very helpful and goggling it will most likely result
in topics regarding oracle patches and the like. In reality this is a
bug with the microsoft oracle client driver. 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.
when we set the IDbDataParameter.Value = (string whose length is : 4000 > length > 2000 )
when we set the IDbDataParameter.DbType = DbType.String
when DB Column is of type NCLOB/CLOB
Unfortunately NHibernate 2.0's default behavior is to do exactly the
above, making it quite more likely to run into this ugly bug when
using nhibernate and oracle.
Solution offered in the blog post: a custom NHibernate Oracle Driver:
/// <summary>
/// Initializes the parameter.
/// </summary>
/// <param name="dbParam">The db param.
/// <param name="name">The name.
/// <param name="sqlType">Type of the SQL.
protected override void InitializeParameter(System.Data.IDbDataParameter dbParam, string name, global::NHibernate.SqlTypes.SqlType sqlType)
{
base.InitializeParameter(dbParam, name, sqlType);
//System.Data.OracleClient.dll driver generates an exception
//we set the IDbDataParameter.Value = (string whose length: 4000 > length > 2000 )
//when we set the IDbDataParameter.DbType = DbType.String
//when 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 will need to be update to use StringClob as the property type
if ((sqlType is StringClobSqlType))
{
((OracleParameter)dbParam).OracleType = OracleType.NClob;
}
}