REST API: Cannot PATCH to an empty field

Audience: Self-hosted and Cloud-hosted customers

Summary

When using a PATCH REST API command on an empty field, you receive a bad request message back:

{
  "meta": {
    "status": "Bad Request",
    "timestamp": "2024-04-07T17:51:18.034+0000",
    "message": "no such path in target JSON document\n{\"op\":\"replace\",\"path\":\"/fields/method$89\",\"value\":\"test\"}"
  }
}

And no update will take place.

Solution

If the field is empty,  you cannot replace it using PATCH. Instead, you will have to use add:

{
  "meta": {
    "status": "OK",
    "timestamp": "2024-04-07T17:53:20.841+0000"
  }
}

Cause

According to RF 6902, which we use for available changes with PATCH (https://datatracker.ietf.org/doc/html/rfc6902#section-4.1), it states for add: 
 
"If the target location specifies an object member that does not exist, a new member is added." 
 
Whereas replace states: 
 
"The "replace" operation replaces the value at the target location with a new value.  The operation object MUST contain a "value" member whose content specifies the replacement value."