mongo-trigger-match-by-specific-field

{
    "$expr": {
        "$not": {
            "$cmp": [{
                "$let": {
                    "vars": {
                        "updated": {
                            "$objectToArray": "$updateDescription.updatedFields"
                        }
                    },
                    "in": {
                        "$arrayElemAt": ["$updated.k", {
                            "$numberInt": "0"
                        }]
                    }
                }
            }, "app.gpsDevice"]
        }
    }
}

Mongo Trigger fire based on a specific field update