What a mapping really is

A mapping is a CONTRACT between two schemas, expressed as expressions rather than code. That framing decides how you approach every one you build. THE SHAPE OF THE TARGET DRIVES EVERYTHING. You are not transforming a source; you are FILLING a target, and the target's structure decides what questions you have to answer. Work target-first, element by element, asking of each: what fills this, and what happens when the source has nothing for it. Working source-first produces a mapping that transfers what happened to be there and leaves target elements nobody thought about. MAPPING IS A DESIGN TASK BEFORE IT IS A BUILD TASK. The build is dragging; the design is deciding what each target element means, where its value comes from, what the default is, and which mismatches between the two schemas are real business questions rather than technical ones. And there are always real business questions. The partner…

In this module: Module 5 · Mappings and transformations

1. 1What a mapping really isFree preview
2. 2The mapper, practically
3. 3Required, optional and the empty element
4. 4Repeating elements and loops
5. 5Conditional mapping
6. 6Functions: strings, numbers and dates
7. 7Dates and time zones, carefully
8. 8Numbers, precision and currency
9. 9Lookups inside a mapping
10. 10Testing a mapping with real data
11. 11Namespaces, and the errors they cause
12. 12Keeping a mapping maintainable
13. 13What breaks: five mapping failures
14. 14Lab briefing · Map two schemas that disagree