When I try to insert a object into the database, then NHibernate does the data binding as expected but the SQL command send to the database has unexpected type settings:

The Log trace from hibernate:

5688 [2112] DEBUG NHibernate.Type.StringType (null) - binding 'mr 1'NHibernateTestClient.exe': Loaded 'c:\projekte\tedradis\entwicklung\trunk\hauptprojekt\src\common\nhibernatetestclient\bin\debug\mono.security.dll', No symbols loaded.
' to parameter: 0
5868 [2112] DEBUG NHibernate.Type.Int32Type (null) - binding '1' to parameter: 1
5868 [2112] DEBUG NHibernate.Type.StringType (null) - binding 'modelrange 1' to parameter: 2
5868 [2112] DEBUG NHibernate.Type.StringType (null) - binding 'fb92f52c579c4369be0f56e1cb00ac45' to parameter: 3
5878 [2112] DEBUG NHibernate.SQL (null) - INSERT INTO modelrange (mr_name, mr_number, mr_comment, guid) VALUES (:p0, :p1, :p2, :p3)
5878 [2112] DEBUG NHibernate.Connection.DriverConnectionProvider (null) - Obtaining IDbConnection from Driver
7580 [2112] DEBUG NHibernate.Impl.BatcherImpl (null) - Closed IDbCommand, open IDbCommands :0
7590 [2112] DEBUG NHibernate.Util.ADOExceptionReporter (null) - could not insert: [DataEntity.ModelRange#fb92f52c579c4369be0f56e1cb00ac45]
Npgsql.NpgsqlException:
length for type varchar must be at least 1
Severity: ERROR
Code: 22023

The Database Log Trace shows:


2005-11-15 17:04:00 STATEMENT: INSERT INTO modelrange (mr_name, mr_number, mr_comment, guid) VALUES ('mr 1'::varchar(0), 1::int4, 'modelrange 1'::varchar(0), '4cb02594b82b438eb138a5acca1e32ea'::varchar(0))


The varchar(0) is incorrect. I have no idea to fix it. I already tried to set the length of the properties in the mapping configuration.

This looks like some Npgsql quirk, try contacting its author, he's quite responsive fixing bugs.

Thanks for the hint.

I tried the Npgsql Driver (Assembly Version 0.7) from src and it works, but I could not get a clou how nhibernate and npgsql work together to create the prepared statement, because the prepare method of the idbcommand implementation in the npgsql is not called :(

This looks like either NHibernate does not set the length of the IDbParameter, or Npgsql has a bug handling the length.