def prepare_changes_data(self, cleaned_data):
    data = cleaned_data.copy()
    # Convert model instances to IDs for JSON serialization
    if data.get("owner"):
        data["owner"] = data["owner"].id
    # Convert dates to ISO format strings
    if data.get("opening_date"):
        data["opening_date"] = data["opening_date"].isoformat()
    if data.get("closing_date"):
        data["closing_date"] = data["closing_date"].isoformat()
    # Convert Decimal fields to strings
    decimal_fields = ["latitude", "longitude", "size_acres", "average_rating"]
    for field in decimal_fields:
        if data.get(field):
            data[field] = str(data[field])
    return data
