Is it possible to change the ItemID of a Portal Item (e.g. a webmap) to a specific value, or to set a specific ItemID when creating a new item? I don't see any API supporting that so I assume it isn't possible...is my assumption correct?
Hello Tobias!
You are correct, it is not possible to specify an itemID or modify an existing one, although I do see some potential value in doing so for certain use cases.
If it does not already exist, I would recommend posting an idea for this here on GeoNet.
-Danny
Here is an update
/addItem: Add Item—ArcGIS REST APIs | ArcGIS Developers
itemIdToCreate | New at 10.8.1. The item ID of the item. The item ID must not exist and must be 32 alphanumeric values. Note:itemIdToCreate applies only to ArcGIS Enterprise. Example itemIdToCreate=832157e321df46f721f9ededbe34ac58 |
Allows to specify the ItemID to Create:
/portal/sharing/rest/content/users/siteadmin/addItem