Work around a bug in Python. ~ is an unreserved character and should not

be quoted in URLs.

CHANGES.txt

@@ -8,6 +8,12 @@ CHANGES
 
 - Document ``scan`` function in API docs.
 
+- Work around an issue in Python where ~ (tilde) is quoted by
+  urllib.quote & urllib.encode, even though it should not be according
+  to the RFC, as ~ is considered unreserved.
+
+  https://www.ietf.org/rfc/rfc3986.txt
+
 0.13 (2016-04-06)
 =================
 

morepath/request.py

@@ -235,14 +235,14 @@ def class_link(self, model, variables=None, name='', app=SAME_APP):
     def _encode_link(self, path, name, parameters):
         parts = []
         if path:
-            parts.append(quote(path.encode('utf-8')))
+            parts.append(fixed_quote(path.encode('utf-8')))
         if name:
             parts.append(name)
         result = self.link_prefix() + '/' + '/'.join(parts)
         if parameters:
             parameters = dict((key, [v.encode('utf-8') for v in value])
                               for (key, value) in parameters.items())
-            result += '?' + urlencode(parameters, True)
+            result += '?' + fixed_urlencode(parameters, True)
         return result
 
     def resolve_path(self, path, app=SAME_APP):
@@ -377,3 +377,27 @@ def mounted_link(path, parameters, app):
         app = app.parent
     result.reverse()
     return '/'.join(result).strip('/'), parameters
+
+
+def fixed_quote(s, safe='/'):
+    """urllib.quote fixed for ~
+
+    Workaround for Python bug:
+
+    https://bugs.python.org/issue16285
+
+    tilde should not be encoded according to RFC3986
+    """
+    return quote(s, safe=safe + '~')
+
+
+def fixed_urlencode(s, doseq=0):
+    """urllib.urlencode fixed for ~
+
+    Workaround for Python bug:
+
+    https://bugs.python.org/issue16285
+
+    tilde should not be encoded according to RFC3986
+    """
+    return urlencode(s, doseq).replace('%7E', '~')

morepath/tests/test_path_directive.py

@@ -1669,6 +1669,42 @@ def link(self, request):
     assert response.body == b'http://localhost/sim%C3%ABple'
 
 
+def test_quoting_link_generation_tilde():
+    # tilde is an unreserved character according to
+    # https://www.ietf.org/rfc/rfc3986.txt but urllib.quote
+    # quotes it anyway. We test whether our workaround using
+    # the safe parameter works
+
+    class App(morepath.App):
+        pass
+
+    class Model(object):
+        def __init__(self):
+            pass
+
+    @App.path(model=Model, path='sim~ple')
+    def get_model():
+        return Model()
+
+    @App.view(model=Model)
+    def default(self, request):
+        return "View"
+
+    @App.view(model=Model, name='link')
+    def link(self, request):
+        return request.link(self)
+
+    dectate.commit(App)
+
+    c = Client(App())
+
+    response = c.get('/sim~ple')
+    assert response.body == b'View'
+
+    response = c.get('/sim~ple/link')
+    assert response.body == b'http://localhost/sim~ple'
+
+
 def test_parameter_quoting():
     class App(morepath.App):
         pass
@@ -1700,6 +1736,37 @@ def link(self, request):
     assert response.body == b'http://localhost/?s=sim%C3%ABple'
 
 
+def test_parameter_quoting_tilde():
+    class App(morepath.App):
+        pass
+
+    class Model(object):
+        def __init__(self, s):
+            self.s = s
+
+    @App.path(model=Model, path='')
+    def get_model(s):
+        return Model(s)
+
+    @App.view(model=Model)
+    def default(self, request):
+        return u"View: %s" % self.s
+
+    @App.view(model=Model, name='link')
+    def link(self, request):
+        return request.link(self)
+
+    dectate.commit(App)
+
+    c = Client(App())
+
+    response = c.get('/?s=sim~ple')
+    assert response.body == u"View: sim~ple".encode('utf-8')
+
+    response = c.get('/link?s=sim~ple')
+    assert response.body == b'http://localhost/?s=sim~ple'
+
+
 def test_class_link_without_variables():
     class App(morepath.App):
         pass