how to use rest-api to patch member interface into lag

[nelliefrance]

I have created device interface et-0/0/28 - 30. Also ae0 lacp interface. How can I patch
https://demo.netbox.dev/api/dcim/interfaces/?device=BB_ACX7100_1&name=BB_ACX7100_1

per https://demo.netbox.dev/api/docs/ for PATCH, the required fileds are device, name, type, with lag as:
lag integer
title: Parent LAG
x-nullable: true

I gave the body of patch as, the 1800 as the lag id of interface ae0
{
"device": 112,
"name": "et-0/0/30",
"type": "100gbase-x-qsfp28",
"lag": 1800
}

But the patch gives an error
{
"non_field_errors": [
"Expected a list of items but got type "dict"."
]
}