Catch API exception and serve helpful error response

apps/greencheck/api/legacy_views.py

@@ -1,19 +1,24 @@
 import json
 import logging
 
-from apps.accounts.models import Hostingprovider, Datacenter
+
 from django.views.decorators.cache import cache_page
 from django_countries import countries
 from rest_framework import response
+from rest_framework import exceptions
 from rest_framework.decorators import api_view, permission_classes, renderer_classes
 from rest_framework.permissions import AllowAny
 from rest_framework_jsonp.renderers import JSONPRenderer
 
+from ...accounts.models import Hostingprovider
 from ..domain_check import GreenDomainChecker
 from ..models import Greencheck, GreenDomain
-from .legacy_image_view import legacy_greencheck_image
 from ..serializers import GreenDomainSerializer
 
+# we import legacy_greencheck_image, to provide one module to import all
+# legacy API views from
+from .legacy_image_view import legacy_greencheck_image  # noqa
+
 logger = logging.getLogger(__name__)
 
 checker = GreenDomainChecker()
@@ -112,7 +117,6 @@ def directory(request):
     country_list = {}
 
     for country in countries:
-
         country_obj = {
             "iso": country.code,
             "tld": f".{country.code.lower()}",
@@ -136,7 +140,19 @@ def directory_provider(self, id):
     what they do, and evidence supporting their
     sustainability claims
     """
-    provider = Hostingprovider.objects.get(pk=id)
+    try:
+        provider_id = int(id)
+    except ValueError as ex:
+        logger.warning(ex)
+        raise exceptions.NotAcceptable(
+            (
+                "You need to send a valid numeric ID to identify the "
+                "provider you are requesting information about. "
+                f"Received ID was: '{id}'"
+            )
+        )
+
+    provider = Hostingprovider.objects.get(pk=provider_id)
     datacenters = [dc.legacy_representation() for dc in provider.datacenter.all() if dc]
 
     # basic case, no datacenters or certificates

apps/greencheck/tests/test_legacy_directory.py

@@ -21,7 +21,6 @@
 
 @pytest.fixture
 def green_dc_certificate(datacenter):
-
     return DatacenterCertificate(
         energyprovider="Some Energy Co.",
         mainenergy_type="mixed",
@@ -138,7 +137,6 @@ class TestGreenWebDirectoryDetail:
     """
 
     def test_directory_provider(self, db, hosting_provider_a, client):
-
         hosting_provider_a.save()
         url_path = reverse("legacy-directory-detail", args=[hosting_provider_a.id])
 
@@ -255,3 +253,29 @@ def test_directory_provider_with_certificates(
         ]:
             assert key in cert
 
+    def test_directory_provider_raises_against_undefined_provider(
+        self, db, hosting_provider_a, client
+    ):
+        """
+        Make sure that when client side code tries to request a provider
+        with the id of 'undefined' we serve an appropriate error
+        40x response, rather than raising an helpful 500 server error
+        """
+        # Given: a valid hosting provider, but an invalid id of 'undefined' from
+        # client side code making requests
+        hosting_provider_a.save()
+        url_path = reverse("legacy-directory-detail", args=["undefined"])
+
+        # When: I send an API reqeest
+        resp = client.get(url_path)
+
+        # Then: I should receive a helpful API error response
+        assert resp.status_code == 406
+
+        # And: with hints about how to fix my request
+        error_detail = resp.data["detail"]
+        error_message = str(error_detail)
+
+        assert error_detail.code == "not_acceptable"
+        assert "You need to send a valid numeric ID" in error_message
+        assert "Received ID was: 'undefined'" in error_message