In this chapter, a description of how to group data into separate data objects has been presented, including the decisions made as to how many data objects are required and how to allocate data to the appropriate object. The benefits of using a consistent naming convention have been described, and some of the conventions used in Ruby and the Rails framework have been introduced. In most real world cases, it can be impossible to avoid data errors, and therefore, the need to ensure that we design systems to cope with and manage data errors has been highlighted. Some methods of controlling and logging user access have been described and their merits and limitations discussed. Data validation and user input control via form design was also discussed.

As many small business applications arise from the imprecise requirements of users, methods to best manage this have been presented. These methods involve the end users throughout the process, creating mock up and prototypes early in the process, and setting clear goals.