Modify Parcel Size & Weight

API Overview

Updates the dimensions and/or weight of a parcel that has already been registered but not yet shipped out on a closed order. Send only the measurements you want to change.

Request Information

• Method: POST
• Path: /api/parcel/edit-parcel-size-weight
• Authentication: Bearer Token

Request Headers

Field	Description
Content-Type	application/json
Authorization	Bearer <token>

Request Parameters

The request body is in JSON format and includes the following fields:

Parameter	Type	Required	Description
wmg_tracking_num	string	Conditional	The WMG tracking number of the parcel. Maximum 60 characters. Either this or tracking_number must be supplied.
tracking_number	string	Conditional	Your own tracking number for the parcel. Maximum 50 characters. Either this or wmg_tracking_num must be supplied.
weight	number	No	New declared weight. Stored with up to 3 decimal places. Omit to leave unchanged.
length	number	No	New length. Stored with up to 2 decimal places. Omit to leave unchanged.
width	number	No	New width. Stored with up to 2 decimal places. Omit to leave unchanged.
height	number	No	New height. Stored with up to 2 decimal places. Omit to leave unchanged.

Request Body Example

{
    "wmg_tracking_num": "CY18000004XX4SG",
    "weight": "12.028",
    "length": "12.08",
    "width": "12.08",
    "height": "12.08"
}

Authentication

This endpoint uses Bearer token authentication.

Obtain a token from Get Token and send it as Authorization: Bearer <Token>.

Response Information

The response is in JSON format.

Response Format

Field	Type	Description
Code	integer	0 = success; non-zero = failure
Message	string	Human-readable result
Data	array	Always an empty array for this endpoint

Success Response

• Status Code: 200

{
    "Code": 0,
    "Message": "Success",
    "Data": []
}

This endpoint returns no payload. A Code of 0 means the parcel was updated.

Error Response

• Status Code: 200 (business logic error) or 4xx/5xx (system error)

{
    "Code": 1,
    "Message": "Parcel Not Found",
    "Data": []
}

Code Reference

Code	Description
0	Success
1	Failure

Example

Bash

BASE_URL="https://api.postal.test.wmgdelivery.com"
TOKEN="your_access_token"

curl -X POST "$BASE_URL/api/parcel/edit-parcel-size-weight" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $TOKEN" \
  -d '{"wmg_tracking_num":"CY18000004XX4SG","weight":"12.028","length":"12.08","width":"12.08","height":"12.08"}'

Windows PowerShell

$BASE_URL = "https://api.postal.test.wmgdelivery.com"
$TOKEN    = "your_access_token"

# Send only the measurements you want to change
$body = @{
    wmg_tracking_num = "CY18000004XX4SG"
    weight           = "12.028"
    length           = "12.08"
    width            = "12.08"
    height           = "12.08"
} | ConvertTo-Json

$response = Invoke-RestMethod -Uri "$BASE_URL/api/parcel/edit-parcel-size-weight" -Method Post `
    -ContentType "application/json" -Body $body -Headers @{Authorization = "Bearer $TOKEN"}
$response | ConvertTo-Json -Depth 10

Python

import requests

BASE_URL = "https://api.postal.test.wmgdelivery.com"
TOKEN    = "your_access_token"

# Send only the measurements you want to change
resp = requests.post(f"{BASE_URL}/api/parcel/edit-parcel-size-weight", json={
    "wmg_tracking_num": "CY18000004XX4SG",
    "weight": "12.028",
    "length": "12.08",
    "width": "12.08",
    "height": "12.08",
}, headers={"Authorization": f"Bearer {TOKEN}"}, timeout=10)
print(resp.json())

Node.js / TypeScript

const BASE_URL = "https://api.postal.test.wmgdelivery.com";
const TOKEN = "your_access_token";

const res = await fetch(`${BASE_URL}/api/parcel/edit-parcel-size-weight`, {
  method: "POST",
  headers: {
    "Content-Type": "application/json",
    "Authorization": `Bearer ${TOKEN}`,
  },
  // Send only the measurements you want to change
  body: JSON.stringify({
    wmg_tracking_num: "CY18000004XX4SG",
    weight: "12.028",
    length: "12.08",
    width: "12.08",
    height: "12.08",
  }),
});
console.log(await res.json());

PHP

<?php
$BASE_URL = 'https://api.postal.test.wmgdelivery.com';
$TOKEN    = 'your_access_token';

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $BASE_URL . '/api/parcel/edit-parcel-size-weight');
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [
    'Content-Type: application/json',
    'Authorization: Bearer ' . $TOKEN,
]);
// Send only the measurements you want to change
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode([
    'wmg_tracking_num' => 'CY18000004XX4SG',
    'weight'           => '12.028',
    'length'           => '12.08',
    'width'            => '12.08',
    'height'           => '12.08',
]));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_TIMEOUT, 10);
$response = curl_exec($ch);
curl_close($ch);

echo json_encode(json_decode($response, true), JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE) . "\n";
?>

Notes

• Identify the parcel with wmg_tracking_num, with tracking_number, or with both. Supplying neither returns Tracking Number or wmg tracking num is invalid. When both are supplied, the parcel must match both values.
• Both identifiers are normalised to upper case before matching, so their case does not matter.
• Omitted measurements are left untouched, so a partial update is the normal case. An explicit 0 is applied — send 0 only if you really mean zero.
• The parcel must not already belong to a closed order. Once its order is closed the measurements are locked and the call returns Parcel was used.
• The resulting length, width, height and weight are validated together against the limits for the parcel's service and destination. Because omitted values fall back to what is already stored, a single new dimension can still push the parcel over a limit — the message names the limit that was breached.
• Every change is recorded against the parcel for audit purposes.
• Only parcels belonging to the authenticated account can be modified.
• All parameters are case-sensitive.

Error Codes

code	message	Description
1	Tracking Number or wmg tracking num is invalid	Neither wmg_tracking_num nor tracking_number was supplied.
1	Parcel Not Found	No parcel in your account matches the supplied identifier(s).
1	Parcel was used	The parcel belongs to an order that has already been closed.
1	max size of wmg_tracking_num must be 60	wmg_tracking_num is longer than 60 characters.
1	max size of tracking_number must be 50	tracking_number is longer than 50 characters.
1		The resulting dimensions or weight exceed the limit for the parcel's service and destination. The message states which limit was breached.
1	Error encountered, please contact tech@wmg-group.com with screenshot of error page for resolution.	Unexpected server error.
1003	Token error	The token is missing, expired, or superseded by a newer login. Call Get Token again.