Best Practice / Design Patterns for data reformat

this is the JSON received from the backend server:

{
    "employee_id": 100464,
    "organization_id": 93,
    "start_date": "2018-09-05",
    "first_name": "Tom",
    "departments": [
        {
            "id": 2761,
            "name": "Sale",
            "organization_id": 93
        },
        {
            "id": 2762,
            "name": "Product",
            "organization_id": 93
        }
    ],
    "primary_department": {
        "id": 2761,
        "name": "Product",
        "organization_id": 93
    }
}

This is the data format I want for, so I need to do some data formatting:

{
    "employee_id": 100464,
    "organization_id": 93,
    "first_name": "Tom",
    "target_department": {
        "department_id": 2761,
        "name": "aProduct",
        "organization_id": 93,
        "is_primary_department": true
    }
}

As you can see, I need to remove, rename, and reformat attributes and the structure of the data.

During the process, there are many potential issues: attributes not existed? My question is what's the best practice for dealing with this issue from programming designing perspective?

I am using Rails, so any good gem or project is dealing with a similar issue?