Merge pull request #106 from Robbie-Palmer/lazy-load-currency-data

Lazy load currency data

Author: abhijeet-1110

forex_python/converter.py

@@ -1,7 +1,8 @@
 import os
 from decimal import Decimal
-import simplejson as json
+
 import requests
+import simplejson as json
 
 
 class RatesNotAvailableError(Exception):
@@ -45,7 +46,7 @@ def _get_decoded_rate(
             self, response, dest_cur, use_decimal=False, date_str=None):
         return self._decode_rates(
             response, use_decimal=use_decimal, date_str=date_str).get(
-                dest_cur, None)
+            dest_cur, None)
 
 
 class CurrencyRates(Common):
@@ -102,7 +103,8 @@ def convert(self, base_cur, dest_cur, amount, date_obj=None):
                 converted_amount = rate * amount
                 return converted_amount
             except TypeError:
-                raise DecimalFloatMismatchError("convert requires amount parameter is of type Decimal when force_decimal=True")
+                raise DecimalFloatMismatchError(
+                    "convert requires amount parameter is of type Decimal when force_decimal=True")
         raise RatesNotAvailableError("Currency Rates Source Not Ready")
 
 
@@ -116,20 +118,22 @@ def convert(self, base_cur, dest_cur, amount, date_obj=None):
 class CurrencyCodes:
 
     def __init__(self):
-        pass
+        self.__currency_data = None
+
+    @property
+    def _currency_data(self):
+        if self.__currency_data is None:
+            file_path = os.path.dirname(os.path.abspath(__file__))
+            with open(file_path + '/raw_data/currencies.json') as f:
+                self.__currency_data = json.loads(f.read())
+        return self.__currency_data
 
     def _get_data(self, currency_code):
-        file_path = os.path.dirname(os.path.abspath(__file__))
-        with open(file_path+'/raw_data/currencies.json') as f:
-            currency_data = json.loads(f.read())
-        currency_dict = next((item for item in currency_data if item["cc"] == currency_code), None)
+        currency_dict = next((item for item in self._currency_data if item["cc"] == currency_code), None)
         return currency_dict
 
     def _get_data_from_symbol(self, symbol):
-        file_path = os.path.dirname(os.path.abspath(__file__))
-        with open(file_path + '/raw_data/currencies.json') as f:
-            currency_data = json.loads(f.read())
-        currency_dict = next((item for item in currency_data if item["symbol"] == symbol), None)
+        currency_dict = next((item for item in self._currency_data if item["symbol"] == symbol), None)
         return currency_dict
 
     def get_symbol(self, currency_code):
@@ -153,7 +157,6 @@ def get_currency_code_from_symbol(self, symbol):
 
 _CURRENCY_CODES = CurrencyCodes()
 
-
 get_symbol = _CURRENCY_CODES.get_symbol
 get_currency_name = _CURRENCY_CODES.get_currency_name
 get_currency_code_from_symbol = _CURRENCY_CODES.get_currency_code_from_symbol