Implementing Manufacturing and Materials Management: From Empty Plant to Costed Work Order · Module 7 · Items and the Item Model
Designing the class hierarchy
Lesson 65 of 188 · 3 min
Classes inherit from parents. Attributes, templates, rules and security defined high up apply below. Inheritance is what keeps a hierarchy small, and it is the mechanism the whole design method rests on. Here is the mistake everyone makes: modelling the marketing category tree. Fifteen product families, sixty sub-families, and a class for each. Now you have seventy-five classes with identical attribute sets and nothing gained — seventy-five things to maintain, seventy-five sets of required attributes to keep in step, seventy-five places for a rule to be applied in seventy-four of them. The right question is: what DIFFERS between these groups in terms of what data we hold about them? That is a different question from "how does the business think about its products". A machined part and a purchased fastener may genuinely need different attributes. Two finished goods in different market segments usually do not — they are the same…
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In this module: Module 7 · Items and the Item Model
- 1What we are building
- 2Why the item model is permanent
- 3The item object model
- 4Master versus organization attributes
- 5Designing the class hierarchy
- 6Item numbering
- 7Building item classes
- 8Item templates
- 9Creating items manually
- 10The attributes that matter most
- 11Assigning items to organizations
- 12Item statuses and lifecycle phases
- 13Importing items in bulk
- 14Data quality before migrationFree preview
- 15What breaks
- 16Lab briefing: the Halden item model
- 17Lab solution walkthrough