Allow viewset to specify lookup value regex for routing

This patch allows a viewset to define a pattern for its lookup field, which the router will honor. Without this patch, any characters are allowed in the lookup field, and overriding this behavior requires subclassing router and copying and pasting the implementation of get_lookup_regex.

It's possible it would be better to remove this functionality from the routers and simply expose a parameter to get_lookup_regex which allows overriding the lookup_regex. That way the viewset config logic could be in the a subclass, which could invoke the super method directly.

I'm using this now for PostgreSQL UUID fields using https://github.com/dcramer/django-uuidfield . Without this patch, that field passes the lookup string to the database driver, which raises a DataError to complain about the invalid UUID. It's possible the field ought to signal this error in a different way, which could obviate the need to specify a pattern.

2 files changed, 35 insertions, 6 deletions

diff --git a/rest_framework/routers.py b/rest_framework/routers.py
index 740d58f0..8766ecb2 100644
--- a/rest_framework/routers.py
+++ b/rest_framework/routers.py
@@ -219,13 +219,21 @@ class SimpleRouter(BaseRouter):
 
         https://github.com/alanjds/drf-nested-routers
         """
-        if self.trailing_slash:
-            base_regex = '(?P<{lookup_prefix}{lookup_field}>[^/]+)'
-        else:
-            # Don't consume `.json` style suffixes
-            base_regex = '(?P<{lookup_prefix}{lookup_field}>[^/.]+)'
+        base_regex = '(?P<{lookup_prefix}{lookup_field}>{lookup_value})'
         lookup_field = getattr(viewset, 'lookup_field', 'pk')
-        return base_regex.format(lookup_field=lookup_field, lookup_prefix=lookup_prefix)
+        try:
+            lookup_value = viewset.lookup_value_regex
+        except AttributeError:
+            if self.trailing_slash:
+                lookup_value = '[^/]+'
+            else:
+                # Don't consume `.json` style suffixes
+                lookup_value = '[^/.]+'
+        return base_regex.format(
+            lookup_prefix=lookup_prefix,
+            lookup_field=lookup_field,
+            lookup_value=lookup_value
+        )
 
     def get_urls(self):
         """
diff --git a/rest_framework/tests/test_routers.py b/rest_framework/tests/test_routers.py
index 1c34648f..0f6d62c7 100644
--- a/rest_framework/tests/test_routers.py
+++ b/rest_framework/tests/test_routers.py
@@ -121,6 +121,27 @@ class TestCustomLookupFields(TestCase):
         )
 
 
+class TestLookupValueRegex(TestCase):
+    """
+    Ensure the router honors lookup_value_regex when applied
+    to the viewset.
+    """
+    def setUp(self):
+        class NoteViewSet(viewsets.ModelViewSet):
+            queryset = RouterTestModel.objects.all()
+            lookup_field = 'uuid'
+            lookup_value_regex = '[0-9a-f]{32}'
+
+        self.router = SimpleRouter()
+        self.router.register(r'notes', NoteViewSet)
+        self.urls = self.router.urls
+
+    def test_urls_limited_by_lookup_value_regex(self):
+        expected = ['^notes/$', '^notes/(?P<uuid>[0-9a-f]{32})/$']
+        for idx in range(len(expected)):
+            self.assertEqual(expected[idx], self.urls[idx].regex.pattern)
+
+
 class TestTrailingSlashIncluded(TestCase):
     def setUp(self):
         class NoteViewSet(viewsets.ModelViewSet):