Keep structured fields before composing a label
A practical US address model separates recipient, street, optional secondary line, city, state code, and postal code. Your interface can compose those fields into a readable preview, but retain the original values for editing and validation. A visual example might show “Taylor Example,” “125 Sample Road,” and “Example City, XX 01234.” Those are illustrative tokens, not a destination to use for registration or delivery.
Treat postal codes as text
Postal codes are identifiers rather than quantities. Converting a five-character value such as “01234” to a number loses information. Keep the string through form state, request serialization, storage, JSON parsing, and CSV import. When you inspect an exported spreadsheet, check that automatic number conversion has not changed it. Display formatting should not silently alter the value that your application later submits.
Test the region and locality relationship
Use the generator’s state and city selectors to obtain a locality sample, then inspect the resulting code and postal field together. When you specify conflicting region, city, and postal filters, an explicit no-result state is more useful than an unrelated substitute. Your own form should also explain a conflict rather than keeping an old success message after the user changes the destination.
- Confirm that the state name and stored two-letter code stay aligned.
- Check that changing a state resets or revalidates an incompatible city.
- Preserve an optional secondary line during preview and editing.
- Exercise long locality names without clipping the postal code or action buttons.
Keep formatting and verification separate
A well-formatted label can still describe a fictional street. This generator provides synthetic street and recipient information; the postal dataset does not verify a particular building or unit. If your application needs delivery verification, show the result from that separate integration and distinguish suggestions from user-entered values. Use generated examples for layout and data handling, then use maintained, authorized fixtures for the service-specific checks that formatting alone cannot establish.