EOAdaptor.Concepts

Creating an EOAdaptor Subclass

Enterprise Objects Framework provides concrete adaptors for three standard relational database management systems-Informix, Oracle, and Sybase-as well as a concrete adaptor for ODBC-compliant databases. You may want to create a subclass of one of these adaptors to extend its behavior, or you may want to create a concrete EOAdaptor subclass for a different database or persistent storage system. EOAdaptor provides many default method implementations that are sufficient for concrete subclasses:

• assignExternalInfoForEntireModel
• connectionDictionary
• contexts
• delegate
• hasOpenChannels
• name

The following methods establish structure and conventions that other Enterprise Objects Framework classes depend on and should be overridden with caution:

• adaptorWithModel
• adaptorWithName
• setExpressionClassName
• setConnectionDictionary
• setDelegate

If you override setConnectionDictionary or setDelegate, your implementations should incorporate the superclass's implementation through a message to super.

The remaining EOAdaptor methods must be overridden by concrete adaptor subclasses in terms of the persistent storage system with which it interacts:

• assignExternalInfoForAttribute
• assignExternalInfoForEntity
• externalTypesWithModel
• internalTypeForExternalType
• assertConnectionDictionaryIsValid
• createAdaptorContext
• fetchedValueForDataValue
• fetchedValueForDateValue
• fetchedValueForNumberValue
• fetchedValueForStringValue
• fetchedValueForValue
• isValidQualifierType

© 2001 Apple Computer, Inc. (Last Published April 13, 2001)