Currency API Updates (#4300)

* Adds an API endpoint for manually updating / refreshing currency data from the server

* Update currency rates manually from the settings page

* Add 'last updated' information to the currency exchange backend

* Load currency exchange data via API (on setings page)

* Bump API version

* Table cleanup

InvenTree/common/api.py

@@ -9,7 +9,7 @@ from django.views.decorators.csrf import csrf_exempt
 
 from django_filters.rest_framework import DjangoFilterBackend
 from django_q.tasks import async_task
-from djmoney.contrib.exchange.models import Rate
+from djmoney.contrib.exchange.models import ExchangeBackend, Rate
 from rest_framework import filters, permissions, serializers
 from rest_framework.exceptions import NotAcceptable, NotFound
 from rest_framework.permissions import IsAdminUser
@@ -104,10 +104,7 @@ class WebhookView(CsrfExemptMixin, APIView):
 
 
 class CurrencyExchangeView(APIView):
-    """API endpoint for displaying currency information
-
-    TODO: Add a POST hook to refresh / update the currency exchange data
-    """
+    """API endpoint for displaying currency information"""
 
     permission_classes = [
         permissions.IsAuthenticated,
@@ -122,9 +119,17 @@ class CurrencyExchangeView(APIView):
         except Exception:
             rates = []
 
+        # Information on last update
+        try:
+            backend = ExchangeBackend.objects.get(name='InvenTreeExchange')
+            updated = backend.last_update
+        except Exception:
+            updated = None
+
         response = {
             'base_currency': common.models.InvenTreeSetting.get_setting('INVENTREE_DEFAULT_CURRENCY', 'USD'),
-            'exchange_rates': {}
+            'exchange_rates': {},
+            'updated': updated,
         }
 
         for rate in rates:
@@ -133,6 +138,29 @@ class CurrencyExchangeView(APIView):
         return Response(response)
 
 
+class CurrencyRefreshView(APIView):
+    """API endpoint for manually refreshing currency exchange rates.
+
+    User must be a 'staff' user to access this endpoint
+    """
+
+    permission_classes = [
+        permissions.IsAuthenticated,
+        permissions.IsAdminUser,
+    ]
+
+    def post(self, request, *args, **kwargs):
+        """Performing a POST request will update currency exchange rates"""
+
+        from InvenTree.tasks import update_exchange_rates
+
+        update_exchange_rates
+
+        return Response({
+            'success': 'Exchange rates updated',
+        })
+
+
 class SettingsList(ListAPI):
     """Generic ListView for settings.
 
@@ -452,6 +480,7 @@ common_api_urls = [
     # Currencies
     re_path(r'^currency/', include([
         re_path(r'^exchange/', CurrencyExchangeView.as_view(), name='api-currency-exchange'),
+        re_path(r'^refresh/', CurrencyRefreshView.as_view(), name='api-currency-refresh'),
     ])),
 
     # Notifications