When ECO builds the O/R mapping layer, it has to decide how to convert the values of the database column to the values of the attributes in the ecospace. This is performed by an attribute mapper, and the O/R mapping layer has to decide which attribute mapper to use for each attribute. To decide this, there is the collection PersistenceMapper.SqlDatabaseConfig.PersistenceMappers. This contains of a collection of name/mapper pairs. The name is normally the CLR-name of a type (such as System.String or System.DateTime), but can be anything. The algorithm for deciding the mapper for an attribute is to look for an attribute mapper in the following order:

• the Tagged Value "PMapper" on the attribute
• The string "ClassName.AttributeName"
• The CLR-name of the type of the attribute

If you want to replace the mapper for all DateTime attributes, then all you need to do is to create your new mapper, and fit it into the collection with the name System.DateTime. The attribute mapper controls the following things:

• how to convert from db to memory and back
• the sql type of the column if we need to generate or evolve a db
• the default db value (practically only used when evolving)
• converting a value to a string literal