How to revert back WorkItems' old component after changing them to new component

How about this:

1. Get Affected Work Item IDs

Use your WIQL query to get the list of affected work items:

GET https://dev.azure.com/{organization}/{project}/_apis/wit/wiql/{queryId}?api-version=6.0

Extract the workItemIds from the response.

2. Fetch Work Item History

For each work item ID, call:

GET https://dev.azure.com/{organization}/{project}/_apis/wit/workItems/{id}/updates?api-version=5.1

• Look for the update where the Component field (or whatever custom field name you're using) was changed.
• Extract the old value from the fields["System.AreaPath"].oldValue or your custom field.

3. Prepare a Patch Payload

Once you have the old value, use a PATCH request to update the work item:

PATCH https://dev.azure.com/{organization}/{project}/_apis/wit/workitems/{id}?api-version=6.0
Content-Type: application/json-patch+json

[
  {
    "op": "add",
    "path": "/fields/Custom.Component",
    "value": "OldComponentValue"
  }
]

Replace Custom.Component with your actual field reference name.

4. Automate with a Script

Use PowerShell, Python, or a tool like Postman Collection Runner to automate this for all 13K items. Here's a Python snippet using requests:

import requests
from requests.auth import HTTPBasicAuth

PAT = 'your_personal_access_token'
headers = {
    'Content-Type': 'application/json-patch+json'
}

def revert_component(work_item_id, old_value):
    url = f"https://dev.azure.com/your_org/your_project/_apis/wit/workitems/{work_item_id}?api-version=6.0"
    payload = [{
        "op": "add",
        "path": "/fields/Custom.Component",
        "value": old_value
    }]
    response = requests.patch(url, json=payload, headers=headers, auth=HTTPBasicAuth('', PAT))
    return response.status_code

# Loop through your work items and call revert_component