DB2/400: ArgumentException Column 'SQL_TYPE_NAME' does not belong to table DataTypes

[shessane]

Using NHibernate to access DB2 AS400 database. When upgrading to NHibernate 5.3.13 from 5.2.7, we face a regression in the FluentConfiguration.BuildSessionFactory() :

FluentNHibernate.Cfg.FluentConfigurationException : An invalid or incomplete configuration was used while creating a SessionFactory. Check PotentialReasons collection, and InnerException for more detail.

---- System.ArgumentException : Column 'SQL_TYPE_NAME' does not belong to table DataTypes.

Stack Trace: 
FluentConfiguration.BuildSessionFactory()

----- Inner Stack Trace -----
DB2MetaData.GetReservedWords()
SchemaMetadataUpdater.GetReservedWords(Dialect dialect, IConnectionHelper connectionHelper)
SchemaMetadataUpdater.UpdateDialectKeywords(Dialect dialect, IConnectionHelper connectionHelper)
SchemaMetadataUpdater.Update(ISessionFactoryImplementor sessionFactory)
SessionFactoryImpl.ctor(Configuration cfg, IMapping mapping, Settings settings, EventListeners listeners)
Configuration.BuildSessionFactory()
FluentConfiguration.BuildSessionFactory()

The problem seems the same as #fluent-nhibernate/504

Here's the line that create the problem :

nhibernate-core/src/NHibernate/Dialect/Schema/DB2MetaData.cs

Line 39 in 4dac4ca

result.Add(row["SQL_TYPE_NAME"].ToString());

In a debug session I can see that there's no colomn named "SQL_TYPE_NAME". I have instead a column named "TypeName".

The workaround consists of disabling IncludeDataTypesInReservedWords :

// ...
fluentConfiguration.Database(DB2400Configuration.Standard.ShowSql().ConnectionString(connectionString)
    .Dialect<CustomDB2As400Dialect>())
//...

public class CustomDB2As400Dialect : DB2400Dialect
{
    public override IDataBaseSchema GetDataBaseSchema(DbConnection connection)
    {
        return new CustomAs400MetaData(connection);
    }

    private class CustomAs400MetaData : DB2MetaData
    {
        public CustomAs400MetaData(DbConnection connection) : base(connection)
        {
        }

        public override bool IncludeDataTypesInReservedWords => false;
    }
}

I'll try to submit a fix that returns if the column "SQL_TYPE_NAME" is not found.

[hazzik]

I'm not entirely sure how this was working in 5.2.x for you, because, in 5.2.7 both DB2Dialect and DB2400Dialect were not implementing GetDataBaseSchema method, and dialect is (still) throwing a NotSupportedException:

nhibernate-core/src/NHibernate/Dialect/Dialect.cs

Lines 491 to 494 in 40779f9

	public virtual IDataBaseSchema GetDataBaseSchema(DbConnection connection)
	{
	throw new NotSupportedException();
	}

[hazzik]

Ok, found how, which is really bad:

nhibernate-core/src/NHibernate/Impl/SessionFactoryImpl.cs

Lines 213 to 228 in ac14311

	try
	{
	if (settings.IsKeywordsImportEnabled)
	{
	SchemaMetadataUpdater.Update(this);
	}
	if (settings.IsAutoQuoteEnabled)
	{
	SchemaMetadataUpdater.QuoteTableAndColumns(cfg, Dialect);
	}
	}
	catch (NotSupportedException ex)
	{
	// Ignore if the Dialect does not provide DataBaseSchema
	log.Warn(ex, "Dialect does not provide DataBaseSchema, but keywords import or auto quoting is enabled.");
	}

In short, you were using incorrect configuration in the first place. This is not a regression per se.

[bahusoid]

This is not a regression per se.

So now DB2400Dialect uses wrong metadata. Still looks like regression to me (as it's caused by #2058)

Your suggestion Restore previous behavior for DB2400Dialect, eg, throwing NotSupportedException; looks like the way to go.

[hazzik]

Sounds good