Enum fields cannot be mapped to database on DB2

Fixed with refactoring of PersistentEnumType (r3568).

This patch solves the enumeration mapping problem on DB2 databases using IBM DB2 Data Provider.

Today I had free time to try to find the bug. I started debugging with a small application that maps a student class with properties id, name, number and "GENDER" to the database. While debugging i compared the property values of inner NHibernate classes for MySQL and DB2 databases. All the values are same for both databases. And i wrote another application using plain OLE DB as below

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Student s = new Student();
s.ID = 2;
s.Name = "Tolga Onbay";
s.Number = 23456;
s.Gender = Gender.Female;

iDB2Connection connection = new iDB2Connection("DataSource=XXXXXXX;UserID=YYYYYYYY;Password=ZZZZZZZZZ;Database=WWWWWW");
connection.Open();

iDB2Command command = new iDB2Command("INSERT INTO S65A2F1D.EMOTDB.OGRENCI (ID, NUMBER, NAME, GENDER) VALUES (?, ?, ?, ?)", connection);

iDB2Parameter paramID = new iDB2Parameter("p1", iDB2DbType.iDB2Integer);
iDB2Parameter paramNumber = new iDB2Parameter("p2", iDB2DbType.iDB2Integer);
iDB2Parameter paramName = new iDB2Parameter("p3", iDB2DbType.iDB2VarChar, 50);
iDB2Parameter paramGender = new iDB2Parameter("p4", iDB2DbType.iDB2Integer);

paramID.Value = s.ID;
paramNumber.Value = s.Number;
paramName.Value = s.Name;
paramGender.Value = s.Gender;

command.Parameters.Add(paramID);
command.Parameters.Add(paramNumber);
command.Parameters.Add(paramName);
command.Parameters.Add(paramGender);

command.ExecuteNonQuery();
connection.Close();

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The code above is throwing an exception as below

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System.NotSupportedException was unhandled
Message="Invalid data type."
Source="IBM.Data.DB2.iSeries"
StackTrace:
at IBM.Data.DB2.iSeries.MPParamConverter.normalizeData(Object& data)
at IBM.Data.DB2.iSeries.iDB2Command.setRowOfParameterData(MpDcData[]& dcDataRow)
at IBM.Data.DB2.iSeries.iDB2Command.execute()
at IBM.Data.DB2.iSeries.iDB2Command.ExecuteNonQuery()
at SampleApp.Program.Main(String[] args) in C:\NHibernate-1.2.1.GA-src\src\SampleApp\Program.cs:line 63
at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()

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I realized that the problem is on IBM DB2 Provider. The db2 parameter is not accepting enum values directly. If i change the line

paramGender.Value = s.Gender;

with this

paramGender.Value = (int) s.Gender;

the problem has gone away.

Then i searched NHibernate code for assigning values to enum properties. In Set method of PersistentEnumType class the value of a enum type is assigning as below

par.Value = value;

Of course the value cannot be directly casted to integer value. So i found GetValue method in same class which i think it is made for just Oracle. Then i change the above line with this and the problem is solved

par.Value = GetValue(value);

I tested this with MySQL and DB2. Also i changed the Genders enum type to long and there is no problem. I think there will be no problem with other databases and enum types.

I attached the patch which is generated for revision 3563 in 1.2.x branch. This solution is OK?

I don't have a DB2 to test this, so I have no idea what the problem is.
The best scenario is that you can create a patch that solve this issue.
I believe that this may be an issue with parameter types set in the ADO parameter set.
But again, can't test that.

I can't understand what you mean with create the ADO.NET code. Could you explain it?