Proposed solution for the NHibernate exception “Column ‘Reserved Word’ does not belong to table ReservedWords.”

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When I updated my NHibernate assembly to version 2.1.0.GA and tried to configure it against my MySQL installation with the .NET Connector v 5.2.7 I got an exception that I hadn’t encounter before:

System.ArgumentException : Column ‘Reserved Word’ does not belong to table ReservedWords.

After some searching and digging I found that this was a common problem when upgrading to the newer versions of the MySQL .NET Connectors and the cause seemed to be that the implementation of the DbConnection.GetSchema in the System.Data.Common namespace that is used when creating .NET connectors isn’t all that clear in MSDN and MySQL had changed their own implementation.

This change caused the exception in NHibernate because in the MySQLMetaData.cs the column name is reference by a hard coded string and thus resulted in a miss match between the column names. Here is the code that caused the problem:

public override ISet<string> GetReservedWords()
{
var result = new HashedSet<string>();
DataTable dtReservedWords = Connection.GetSchema(DbMetaDataCollectionNames.ReservedWords);
foreach (DataRow row in dtReservedWords.Rows)
{
result.Add(row["Reserved Word"].ToString());
}
return result;
}

Looking into how the MySQL team had implemented their connector and how NHibernate works and also searching through the documentation for the System.Data.Common namespace I propose a solution to this problem by using a similar approach as when calling the GetSchema with the static DbMetaDataCollectionNames.ReservedWords parameter and use the also static DbMetaDataColumnNames.ReservedWord when retrieving the reserved words column, resulting in the following:

public override ISet<string> GetReservedWords()
{
var result = new HashedSet<string>();
DataTable dtReservedWords = Connection.GetSchema(DbMetaDataCollectionNames.ReservedWords);

foreach (DataRow row in dtReservedWords.Rows)
{
result.Add(row[DbMetaDataColumnNames.ReservedWord].ToString());
}
return result;
}

I have tested this solution against NHibernate 2.1.0.GA with the MySQL connectors 5.1.7, 5.2.7 and 6.0.4 and they seems to play nice with this update. See the issue here