webhook condition - trigger on change

[jnc27]

I would like to fire the webhook if there was a change in a specific custom field.
I couldn't find a way to retrieve the values. I was thinking it could work like this:

    {
        "attr": "snapshots.prechange.custom_fields.cf_test",
        "negate": true,
        "value": "data.custom_fields.cf_test"
    }

[candlerb]

I think you've reached the limits of what's possible in webhook filtering. Your example looks for the case where the target field is not the literal value "data.custom_fields.cf_test"

Doing anything more sophisticated would involve changing Netbox, either to allow you to plug in python code here (as is possible with custom validation), or to use a more powerful expression language like Jsonnet:

# A webhook condition expressed as a Jsonnet function
function(obj)
  obj.snapshots.prechange.custom_fields.cf_test != obj.snapshots.postchange.custom_fields.cf_test

local f = import 'cond.libsonnet';
local data = {
  snapshots: {
    prechange: {
      custom_fields: {
        cf_test: "abc",
      },
    },
    postchange: {
      custom_fields: {
        cf_test: "def",
      },
    },
  },
};
f(data)

But for now, I think this logic needs to live in your webhook receiver.