Merge pull request #201 from readthedocs/davidfischer/variables-in-ad…

…-links

Allow simple variables in Advertisement.link

adserver/models.py

@@ -891,6 +891,8 @@ class Advertisement(TimeStampedModel, IndestructibleModel):
         blank=True,
         help_text=_("Different ad types have different text requirements"),
     )
+    # Supports simple variables like ${publisher} and ${advertisement}
+    # using string.Template syntax
     link = models.URLField(_("Link URL"), max_length=255)
     image = models.ImageField(
         _("Image"),

adserver/tests/test_api.py

@@ -1046,6 +1046,27 @@ def test_view_tracking_invalid_ad(self):
         resp = self.client.get(url)
         self.assertEqual(resp.status_code, 404)
 
+    def test_click_tracking_variable_expansion(self):
+        self.ad.link = "http://example.com?utm_source=${publisher}"
+        self.ad.save()
+
+        resp = self.client.get(self.click_url)
+
+        self.assertEqual(resp.status_code, 302)
+        self.assertEqual(
+            resp["Location"], "http://example.com?utm_source=test-publisher"
+        )
+
+        # invalid string replacement template
+        self.ad.link = "http://example.com?utm_source=$%7Btest%7Bpublisher&t=1"
+        self.ad.save()
+
+        resp = self.client.get(self.click_url)
+
+        # Even with an invalid template, this should "work" without failing
+        self.assertEqual(resp.status_code, 302)
+        self.assertEqual(resp["Location"], self.ad.link)
+
     def test_click_tracking_valid(self):
         resp = self.client.get(self.click_url)
 

adserver/views.py

@@ -2,6 +2,7 @@
 import collections
 import csv
 import logging
+import string
 from datetime import datetime
 from datetime import timedelta
 
@@ -416,7 +417,7 @@ def get(self, request, advertisement_id, nonce):
             )
 
         message = ignore_reason or self.success_message
-        response = self.get_response(request, advertisement)
+        response = self.get_response(request, advertisement, publisher)
 
         self.send_to_analytics(request, advertisement, message)
 
@@ -427,7 +428,7 @@ def get(self, request, advertisement_id, nonce):
 
         return response
 
-    def get_response(self, request, advertisement):
+    def get_response(self, request, advertisement, publisher):
         """Subclasses *must* override this method."""
         raise NotImplementedError
 
@@ -439,7 +440,7 @@ class AdViewProxyView(BaseProxyView):
     impression_type = VIEWS
     success_message = "Billed view"
 
-    def get_response(self, request, advertisement):
+    def get_response(self, request, advertisement, publisher):
         return HttpResponse(
             "<svg><!-- View Proxy --></svg>", content_type="image/svg+xml"
         )
@@ -473,8 +474,13 @@ def send_to_analytics(self, request, advertisement, message):
             uip=ip_address,  # will be anonymized
         )
 
-    def get_response(self, request, advertisement):
-        return HttpResponseRedirect(advertisement.link)
+    def get_response(self, request, advertisement, publisher):
+        # Allows using variables in links such as `?utm_source=${publisher}`
+        template = string.Template(advertisement.link)
+        url = template.safe_substitute(
+            publisher=publisher.slug, advertisement=advertisement.slug
+        )
+        return HttpResponseRedirect(url)
 
 
 class BaseReportView(UserPassesTestMixin, TemplateView):