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How to Expand a Contract and Migrate Data in Python

Expand an old data contract by renaming fields and adding defaults, then migrate to a final version with deepcopy isolation.

contract migration deepcopy

Python

import json
from copy import deepcopy

# Mock data representing a user record (old contract)
old_contract = {
    "id": 1,
    "name": "Alice",
    "email": "alice@example.com",
    "age": 30,
    "status": "active"
}

# Expanded contract: adds fields with defaults and renames some fields
expand_rules = {
    "id": "u…

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