for i in range(0,len(user_list)):
    collection_4.update_one({'user_id':ObjectId(user_list[i])},{'$set':{'products': temp_list }},upsert=True)

This is giving me error, TypeError: list indices must be integers or slices, not ObjectId

collection_4.update_one({'user_id':ObjectId("5c471d607f")},{'$set':{'products': temp_list }},upsert=True)