A catalogue supplier may propose changing a free-text dimension into a typed measurement. Before approving a schema edit, decide which old values can be mapped, which require review and which must remain unresolved. A tidy field definition does not prove the catalogue survived.
Primary evidence and claim boundaries
Shopify warns that migrating between incompatible metafield types makes existing values invalid. Definition changes need a value-level migration plan. Primary reference · Read 17 October 2026.
Filled acceptance example
Synthetic teaching scenario, not a client case, provider integration test or business result. Scroll the example table on narrow screens.
| Synthetic old value | Proposed typed output | Decision |
|---|---|---|
| P1: “120 cm” | dimension:120 CENTIMETERS | Map after unit confirmation |
| P2: “1.2 m” | dimension:1.2 METERS | Equivalent120 cm; preserve original evidence |
| P3: “120” | Unit unknown | Quarantine; do not assume cm |
| P4: “120–140 cm adjustable” | Single scalar loses range | Needs a different data model |
Practical handover procedure
- Export a protected snapshot with product ID, namespace/key, current type and exact raw value. Agree the target type and unit vocabulary with the catalogue owner.
- Run an offline mapping first. Mark ambiguous units and ranges as blocked rather than cleaning them into plausible numbers. Keep a reversible old-to-new mapping keyed by stable product ID.
- Rehearse on authorised test data, verify template rendering and export readback, then ask the merchant to approve the change plan and rollback procedure.
Interpret the outcome
Only two of four rows are presently mappable. P3 is not zero, and P4 is not simply 120. Counting “four fields migrated” would conceal two information losses. A useful supplier quote includes the exception workload and the display changes required by the new type.
Acceptance decision
Require full input-row reconciliation, explicit blocked rows and a readback of typed values plus rendered outputs. Passing a JSON shape check alone is insufficient.
Limits and unverified work
Illustrative mapping, not a Shopify API call or universal conversion tool. Actual target types, validation constraints, app dependencies and compatibility must be checked against the chosen version and store.
Download the filled bilingual acceptance record — Contains these inputs, steps, expectations and limits. This is a teaching record, not an executable integration.