Fix URL pattern parsing in schema generation (#5689)

* Fix url parsing in schema generation

- Call `str(pattern)` to get non-escaped route
- Strip converters from path to comply with uritemplate format. 
   Background: https://github.com/encode/django-rest-framework/issues/5675#issuecomment-352829363

Fixes #5675

rest_framework/compat.py

@@ -32,7 +32,7 @@ except ImportError:
 def get_regex_pattern(urlpattern):
     if hasattr(urlpattern, 'pattern'):
         # Django 2.0
-        return urlpattern.pattern.regex.pattern
+        return str(urlpattern.pattern)
     else:
         # Django < 2.0
         return urlpattern.regex.pattern
@@ -255,6 +255,14 @@ try:
 except ImportError:
     InvalidTimeError = Exception
 
+# Django 1.x url routing syntax. Remove when dropping Django 1.11 support.
+try:
+    from django.urls import include, path, re_path # noqa
+except ImportError:
+    from django.conf.urls import include, url # noqa
+    path = None
+    re_path = url
+
 
 # `separators` argument to `json.dumps()` differs between 2.x and 3.x
 # See: http://bugs.python.org/issue22767

rest_framework/schemas/generators.py

@@ -3,6 +3,7 @@ generators.py   # Top-down schema generation
 
 See schemas.__init__.py for package overview.
 """
+import re
 import warnings
 from collections import Counter, OrderedDict
 from importlib import import_module
@@ -135,6 +136,11 @@ def endpoint_ordering(endpoint):
     return (path, method_priority)
 
 
+_PATH_PARAMETER_COMPONENT_RE = re.compile(
+    r'<(?:(?P<converter>[^>:]+):)?(?P<parameter>\w+)>'
+)
+
+
 class EndpointEnumerator(object):
     """
     A class to determine the available API endpoints that a project exposes.
@@ -189,7 +195,9 @@ class EndpointEnumerator(object):
         Given a URL conf regex, return a URI template string.
         """
         path = simplify_regex(path_regex)
-        path = path.replace('<', '{').replace('>', '}')
+
+        # Strip Django 2.0 convertors as they are incompatible with uritemplate format
+        path = re.sub(_PATH_PARAMETER_COMPONENT_RE, r'{\g<parameter>}', path)
         return path
 
     def should_include_endpoint(self, path, callback):

tests/test_schemas.py

@@ -9,7 +9,7 @@ from django.test import TestCase, override_settings
 from rest_framework import (
     filters, generics, pagination, permissions, serializers
 )
-from rest_framework.compat import coreapi, coreschema, get_regex_pattern
+from rest_framework.compat import coreapi, coreschema, get_regex_pattern, path
 from rest_framework.decorators import (
     api_view, detail_route, list_route, schema
 )
@@ -361,6 +361,59 @@ class TestSchemaGenerator(TestCase):
         assert schema == expected
 
 
+@unittest.skipUnless(coreapi, 'coreapi is not installed')
+@unittest.skipUnless(path, 'needs Django 2')
+class TestSchemaGeneratorDjango2(TestCase):
+    def setUp(self):
+        self.patterns = [
+            path('example/', ExampleListView.as_view()),
+            path('example/<int:pk>/', ExampleDetailView.as_view()),
+            path('example/<int:pk>/sub/', ExampleDetailView.as_view()),
+        ]
+
+    def test_schema_for_regular_views(self):
+        """
+        Ensure that schema generation works for APIView classes.
+        """
+        generator = SchemaGenerator(title='Example API', patterns=self.patterns)
+        schema = generator.get_schema()
+        expected = coreapi.Document(
+            url='',
+            title='Example API',
+            content={
+                'example': {
+                    'create': coreapi.Link(
+                        url='/example/',
+                        action='post',
+                        fields=[]
+                    ),
+                    'list': coreapi.Link(
+                        url='/example/',
+                        action='get',
+                        fields=[]
+                    ),
+                    'read': coreapi.Link(
+                        url='/example/{id}/',
+                        action='get',
+                        fields=[
+                            coreapi.Field('id', required=True, location='path', schema=coreschema.String())
+                        ]
+                    ),
+                    'sub': {
+                        'list': coreapi.Link(
+                            url='/example/{id}/sub/',
+                            action='get',
+                            fields=[
+                                coreapi.Field('id', required=True, location='path', schema=coreschema.String())
+                            ]
+                        )
+                    }
+                }
+            }
+        )
+        assert schema == expected
+
+
 @unittest.skipUnless(coreapi, 'coreapi is not installed')
 class TestSchemaGeneratorNotAtRoot(TestCase):
     def setUp(self):