Adding JSON to an array in mongo database

I'm trying to add a json map to an array in my database using monger but there is something wrong. I've found how to do it in monger documentation, but $push and $addToSet aren't working:

Here is my function:

(defn add-vehicle [vehicle]
    (let [connect-string (System/getenv "MONGO_CONNECTION")
          {:keys [conn db]} (mg/connect-via-uri connect-string)]
        (mc/update db "drivers-collection" 
                   {:email (:email vehicle)} 
                   {$addToSet {:cars (:vehicle vehicle)}})))

And this is how I'm calling this function in nREPL:

(add-vehicle {:email "teste111@hotmail.com" 
              :vehicle {:model "fusca" 
                        :color "rosa" 
                        :plate "AIO-9807"}})

Any ideas?

EDIT

This is my document in drivers-collection:

{
    "_id": {
        "$oid": "57bee61edcba0f2f7559eb56"
    },
    "email": "teste111@hotmail.com",
    "name": "Guilherme Job",
    "cars": [],
    "customerId": "cus_9O4dhvtuF2926m"
}

My car's array are empty and I'm trying to add a vehicle into it.

Solution

Make sure that your query part of monger.collection/update call contains a correct criteria. You should also inspect the WriteResult returned by Mongo driver to see if they were successful or not.

I have tested using $push in REPL and everything works correctly. As you can see a car is added:

(require '[monger.core :as mg])
(require '[monger.collection :as mc])
(require '[monger.operators :refer :all])

(def conn (mg/connect))
(def db (mg/get-db conn "test-db"))
(def coll "test-collection")

(mc/insert db coll {:email "a@example.com" :name "Guilherme Job" :cars []})

(mc/find-maps db coll)
;; => ({:_id #object[org.bson.types.ObjectId 0x58f153ea "580e826e7e92729ffb000611"], :email "a@example.com", :name "Guilherme Job", :cars []})

(mc/update db coll {:email" "a@example.com"} {$push {:cars" {:name "Ford"}}})

(mc/find-maps db coll)
;; => ({:_id #object[org.bson.types.ObjectId 0x494168cd "580e826e7e92729ffb000611"], :email "a@example.com", :name "Guilherme Job", :cars [{:name "Ford"}]})