Repository: falconry/falcon

Issue:
URI template conflicts after router update
I have been abusing the route order a bit, and would like to know if there is a way to do this with the new router, or if this is actually a bug.

``` python
application = falcon.API()
application.add_route('/action1', Action1Handler())
application.add_route('/action2', Action2Handler())
application.add_route('/action3', Action3Handler())
application.add_route('/{action}', ActionFallbackHandler())
```

I realize this is probably a strange use case, and I could move the top 3 handlers into the bottom one and just relay the requests to the various other handlers, but this way seems cleaner.



Discussion:
Interesting, thanks for sharing your use case. Let me take a look and see what it would take to support this in the new router, since I'd rather not have a regression in functionality.

Please see https://github.com/falconry/falcon/pull/536

I'm not sure if that introduces some more obscure bug, but the tests pass at least.


Resolving patch:
diff --git a/falcon/routing/compiled.py b/falcon/routing/compiled.py
--- a/falcon/routing/compiled.py
+++ b/falcon/routing/compiled.py
@@ -29,74 +29,6 @@ class CompiledRouter(object):
     tree for each look-up, it generates inlined, bespoke Python code to
     perform the search, then compiles that code. This makes the route
     processing quite fast.
-
-    The generated code looks something like this::
-
-        def find(path, return_values, expressions, params):
-            path_len = len(path)
-            if path_len > 0:
-                if path[0] == "repos":
-                    if path_len > 1:
-                        params["org"] = path[1]
-                        if path_len > 2:
-                            params["repo"] = path[2]
-                            if path_len > 3:
-                                if path[3] == "commits":
-                                    return return_values[3]
-                                if path[3] == "compare":
-                                    if path_len > 4:
-                                        match = expressions[0].match(path[4])
-                                        if match is not None:
-                                            params.update(match.groupdict())
-                                            if path_len > 5:
-                                                if path[5] == "full":
-                                                    return return_values[5]
-                                                if path[5] == "part":
-                                                    return return_values[6]
-                                                return None
-                                            return return_values[4]
-                                        if path[4] == "all":
-                                            return return_values[7]
-                                        match = expressions[1].match(path[4])
-                                        if match is not None:
-                                            params.update(match.groupdict())
-                                            if path_len > 5:
-                                                if path[5] == "full":
-                                                    return return_values[9]
-                                                return None
-                                            return return_values[8]
-                                        return None
-                                    return None
-                                return None
-                            return return_values[2]
-                        return return_values[1]
-                    return return_values[0]
-                if path[0] == "teams":
-                    if path_len > 1:
-                        params["id"] = path[1]
-                        if path_len > 2:
-                            if path[2] == "members":
-                                return return_values[11]
-                            return None
-                        return return_values[10]
-                    return None
-                if path[0] == "user":
-                    if path_len > 1:
-                        if path[1] == "memberships":
-                            return return_values[12]
-                        return None
-                    return None
-                if path[0] == "emojis":
-                    if path_len > 1:
-                        if path[1] == "signs":
-                            if path_len > 2:
-                                params["id"] = path[2]
-                                return return_values[14]
-                            return None
-                        return None
-                    return return_values[13]
-                return None
-            return None
     """
 
     def __init__(self):
@@ -125,6 +57,7 @@ def insert(nodes, path_index=0):
                 if node.matches(segment):
                     path_index += 1
                     if path_index == len(path):
+                        # NOTE(kgriffs): Override previous node
                         node.method_map = method_map
                         node.resource = resource
                     else:
@@ -179,6 +112,10 @@ def line(text, indent_offset=0):
         level_indent = indent
         found_simple = False
 
+        # NOTE(kgriffs): Sort static nodes before var nodes so that
+        # none of them get masked. False sorts before True.
+        nodes = sorted(nodes, key=lambda node: node.is_var)
+
         for node in nodes:
             if node.is_var:
                 if node.is_complex:
@@ -225,7 +162,13 @@ def line(text, indent_offset=0):
             if node.resource is None:
                 line('return None')
             else:
-                line('return return_values[%d]' % resource_idx)
+                # NOTE(kgriffs): Make sure that we have consumed all of
+                # the segments for the requested route; otherwise we could
+                # mistakenly match "/foo/23/bar" against "/foo/{id}".
+                line('if path_len == %d:' % (level + 1))
+                line('return return_values[%d]' % resource_idx, 1)
+
+                line('return None')
 
             indent = level_indent
 
@@ -326,7 +269,7 @@ def conflicts_with(self, segment):
         #
         #   simple, simple ==> True
         #   simple, complex ==> True
-        #   simple, string ==> True
+        #   simple, string ==> False
         #   complex, simple ==> True
         #   complex, complex ==> False
         #   complex, string ==> False
@@ -334,7 +277,6 @@ def conflicts_with(self, segment):
         #   string, complex ==> False
         #   string, string ==> False
         #
-
         other = CompiledRouterNode(segment)
 
         if self.is_var:
@@ -352,10 +294,13 @@ def conflicts_with(self, segment):
                 #   /foo/{thing1}
                 #   /foo/{thing2}
                 #
-                # or
+                # On the other hand, this is OK:
                 #
                 #   /foo/{thing1}
                 #   /foo/all
-                return True
+                #
+                return other.is_var
 
+        # NOTE(kgriffs): If self is a static string match, then all the cases
+        # for other are False, so no need to check.
         return False


Test patch:
diff --git a/tests/test_default_router.py b/tests/test_default_router.py
--- a/tests/test_default_router.py
+++ b/tests/test_default_router.py
@@ -7,6 +7,9 @@ class ResourceWithId(object):
     def __init__(self, resource_id):
         self.resource_id = resource_id
 
+    def __repr__(self):
+        return 'ResourceWithId({0})'.format(self.resource_id)
+
     def on_get(self, req, resp):
         resp.body = self.resource_id
 
@@ -36,19 +39,33 @@ def setup_routes(router_interface):
         {}, ResourceWithId(10))
     router_interface.add_route(
         '/repos/{org}/{repo}/compare/all', {}, ResourceWithId(11))
+
+    # NOTE(kgriffs): The ordering of these calls is significant; we
+    # need to test that the {id} field does not match the other routes,
+    # regardless of the order they are added.
     router_interface.add_route(
         '/emojis/signs/0', {}, ResourceWithId(12))
     router_interface.add_route(
         '/emojis/signs/{id}', {}, ResourceWithId(13))
+    router_interface.add_route(
+        '/emojis/signs/42', {}, ResourceWithId(14))
+    router_interface.add_route(
+        '/emojis/signs/42/small', {}, ResourceWithId(14.1))
+    router_interface.add_route(
+        '/emojis/signs/78/small', {}, ResourceWithId(14.1))
+
     router_interface.add_route(
         '/repos/{org}/{repo}/compare/{usr0}:{branch0}...{usr1}:{branch1}/part',
-        {}, ResourceWithId(14))
+        {}, ResourceWithId(15))
     router_interface.add_route(
         '/repos/{org}/{repo}/compare/{usr0}:{branch0}',
-        {}, ResourceWithId(15))
+        {}, ResourceWithId(16))
     router_interface.add_route(
         '/repos/{org}/{repo}/compare/{usr0}:{branch0}/full',
-        {}, ResourceWithId(16))
+        {}, ResourceWithId(17))
+
+    router_interface.add_route(
+        '/gists/{id}/raw', {}, ResourceWithId(18))
 
 
 @ddt.ddt
@@ -61,14 +78,23 @@ def before(self):
     @ddt.data(
         '/teams/{collision}',
         '/repos/{org}/{repo}/compare/{simple-collision}',
-        '/emojis/signs/1',
+        '/emojis/signs/{id_too}',
     )
     def test_collision(self, template):
         self.assertRaises(
             ValueError,
-            self.router.add_route, template, {}, ResourceWithId(6)
+            self.router.add_route, template, {}, ResourceWithId(-1)
         )
 
+    def test_dump(self):
+        print(self.router._src)
+
+    def test_override(self):
+        self.router.add_route('/emojis/signs/0', {}, ResourceWithId(-1))
+
+        resource, method_map, params = self.router.find('/emojis/signs/0')
+        self.assertEqual(resource.resource_id, -1)
+
     def test_missing(self):
         resource, method_map, params = self.router.find('/this/does/not/exist')
         self.assertIs(resource, None)
@@ -90,17 +116,24 @@ def test_literal_segment(self):
         resource, method_map, params = self.router.find('/emojis/signs/1')
         self.assertEqual(resource.resource_id, 13)
 
-    def test_dead_segment(self):
-        resource, method_map, params = self.router.find('/teams')
-        self.assertIs(resource, None)
+        resource, method_map, params = self.router.find('/emojis/signs/42')
+        self.assertEqual(resource.resource_id, 14)
 
-        resource, method_map, params = self.router.find('/emojis/signs')
-        self.assertIs(resource, None)
+        resource, method_map, params = self.router.find('/emojis/signs/42/small')
+        self.assertEqual(resource.resource_id, 14.1)
 
-        resource, method_map, params = self.router.find('/emojis/signs/stop')
-        self.assertEqual(params, {
-            'id': 'stop',
-        })
+        resource, method_map, params = self.router.find('/emojis/signs/1/small')
+        self.assertEqual(resource, None)
+
+    @ddt.data(
+        '/teams',
+        '/emojis/signs',
+        '/gists',
+        '/gists/42',
+    )
+    def test_dead_segment(self, template):
+        resource, method_map, params = self.router.find(template)
+        self.assertIs(resource, None)
 
     def test_malformed_pattern(self):
         resource, method_map, params = self.router.find(
@@ -120,6 +153,16 @@ def test_variable(self):
         self.assertEqual(resource.resource_id, 6)
         self.assertEqual(params, {'id': '42'})
 
+        resource, method_map, params = self.router.find('/emojis/signs/stop')
+        self.assertEqual(params, {'id': 'stop'})
+
+        resource, method_map, params = self.router.find('/gists/42/raw')
+        self.assertEqual(params, {'id': '42'})
+
+    def test_subsegment_not_found(self):
+        resource, method_map, params = self.router.find('/emojis/signs/0/x')
+        self.assertIs(resource, None)
+
     def test_multivar(self):
         resource, method_map, params = self.router.find(
             '/repos/racker/falcon/commits')
@@ -131,7 +174,7 @@ def test_multivar(self):
         self.assertEqual(resource.resource_id, 11)
         self.assertEqual(params, {'org': 'racker', 'repo': 'falcon'})
 
-    @ddt.data(('', 5), ('/full', 10), ('/part', 14))
+    @ddt.data(('', 5), ('/full', 10), ('/part', 15))
     @ddt.unpack
     def test_complex(self, url_postfix, resource_id):
         uri = '/repos/racker/falcon/compare/johndoe:master...janedoe:dev'
@@ -147,7 +190,7 @@ def test_complex(self, url_postfix, resource_id):
             'branch1': 'dev'
         })
 
-    @ddt.data(('', 15), ('/full', 16))
+    @ddt.data(('', 16), ('/full', 17))
     @ddt.unpack
     def test_complex_alt(self, url_postfix, resource_id):
         uri = '/repos/falconry/falcon/compare/johndoe:master'