client = MongoClient('localhost', 27017)
db = client['countries_db']
collection_currency = db['currency']

with open('currencies.json') as f:
    file_data = json.load(f)

collection_currency.insert(file_data) # pymongo < 3.0
collection_currency.insert_one(file_data) # pymongo >= 3.0
collection_currency.insert_many(file_data) # pymongo >= 3.0

client.close()