Question

My application supports both Oracle and MS SQL databases, with slightly different schemas having been implemented for each. One issue I’ve run into is a class that has an auto-increment primary key under MS SQL, but a manually-inserted primary key under Oracle.

Right now, the two different mappings for the class look like this:

Oracle:

<class lazy='false' name='EntityPropertyName' table='entity_property_name' > <id name='ID' column='id' type='Int32' unsaved-value='-1'>   <generator class='increment' /> </id> <property name='Name' column='name'/> 

MS SQL:

<class lazy='false' name='EntityPropertyName' table='entity_property_name' > <id name='ID' column='id' type='Int32' unsaved-value='-1'>   <generator class='native'>   </generator> </id> <property name='Name' column='name'/> 

This isn’t the worst thing in the world, because I can put them into different mapping files and load the correct one at runtime.

NHibernate.Cfg.Configuration cfg = new NHibernate.Cfg.Configuration();              if (newDBType == CompanyName.AppName.Data.Enum.DatabaseType.MsSqlServer)             {                 cfg.Properties['dialect'] = 'NHibernate.Dialect.MsSql2000Dialect';                 cfg.Properties['connection.driver_class'] = 'NHibernate.Driver.SqlClientDriver';                 cfg.AddFile('DataTypes\\MSSQLTypes.hbm.xml');             }             else             {                 cfg.Properties['dialect'] = 'NHibernate.Dialect.Oracle9Dialect';                 cfg.Properties['connection.driver_class'] = 'NHibernate.Driver.OracleClientDriver';                 cfg.AddFile('DataTypes\\OracleTypes.hbm.xml');             }              cfg.Properties['connection.provider'] = 'NHibernate.Connection.DriverConnectionProvider';              cfg.Properties['connection.connection_string'] = connectionString;              cfg.AddAssembly('CompanyName.AppName.Data');              Sessions = cfg.BuildSessionFactory(); 

The thing I dislike about this strategy though is that I now have some ugly XML files in my program’s bin directory, which need to be there or the application won’t work. It would be a lot better if I could embed the different files into the resource like I can with my main mapping file, but choose whether to load each file or not at runtime.

Is there any way to do this, or perhaps a different way to solve the problem?

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Edit: Thank you, Cristian! You did understand the question, I was just unaware that resources could be loaded by NHibernate like that. Thinking on it, I suppose it makes sense for the AddAssembly method would have to have some way to enumerate and load the resources that it finds!

My solution ended up being:

NHibernate.Cfg.Configuration cfg = new NHibernate.Cfg.Configuration();              if (newDBType == CompanyName.AppName.Data.Enum.DatabaseType.MsSqlServer)             {                 cfg.Properties['dialect'] = 'NHibernate.Dialect.MsSql2000Dialect';                 cfg.Properties['connection.driver_class'] = 'NHibernate.Driver.SqlClientDriver';                 cfg.AddInputStream(Assembly.GetExecutingAssembly().GetManifestResourceStream('CompanyName.AppName.Data.DataTypes.MSSQLTypes.hbm.xml'));             }             else             {                 cfg.Properties['dialect'] = 'NHibernate.Dialect.Oracle9Dialect';                 cfg.Properties['connection.driver_class'] = 'NHibernate.Driver.OracleClientDriver';                 cfg.AddInputStream(Assembly.GetExecutingAssembly().GetManifestResourceStream('CompanyName.AppName.Data.DataTypes.OracleTypes.hbm.xml'));             }              cfg.Properties['connection.provider'] = 'NHibernate.Connection.DriverConnectionProvider';              cfg.Properties['connection.connection_string'] = connectionString;              cfg.AddInputStream(Assembly.GetExecutingAssembly().GetManifestResourceStream('CompanyName.AppName.Data.DataTypes.Types.hbm.xml'));              Sessions = cfg.BuildSessionFactory(); 

Answer 1

I might be missing your crucial point. NHibernate is quite flexible in how you can feed it the mapping files. e.g.

cfg.AddInputStream(assembly.GetManifestResourceStream('MyNamespace.MyEmbeddedresource.hbm.xml')); 

or a custom built xml string:

cfg.AddXml(myCustomBuildXmlString); 

You can also add mappings programmatically directly but that’s a bit trickier.