Merge lp:~cjwatson/lazr.restful/url-dereferencing-better-environ into lp:lazr.restful

[Colin Watson]

Make ObjectLookupFieldMarshaller accept URLs that redirect.

The redirected-to resource must have a context attribute that evaluates to the appropriate model object.

Among other things, this makes it more feasible to adjust the URL layout of exported resources.

[Ioana Lasc (ilasc)]

looks good

review: Approve

=== modified file 'NEWS.rst'
--- NEWS.rst	2020-06-30 13:33:53 +0000
+++ NEWS.rst	2020-06-30 15:58:27 +0000
@@ -7,6 +7,10 @@
 
 Fix test failure with zope.interface >= 5.0.0.
 
+Make ``ObjectLookupFieldMarshaller`` accept URLs that redirect, provided
+that the redirected-to resource has a ``context`` attribute that evaluates
+to the appropriate model object.
+
 0.22.0 (2020-06-12)
 ===================
 
 
=== modified file 'src/lazr/restful/_resource.py'
--- src/lazr/restful/_resource.py	2020-05-12 11:57:28 +0000
+++ src/lazr/restful/_resource.py	2020-06-30 15:58:27 +0000
@@ -122,6 +122,7 @@
     IWebServiceVersion,
     LAZR_WEBSERVICE_NAME,
     )
+from lazr.restful.marshallers import URLDereferencingMixin
 from lazr.restful.utils import (
     extract_write_portion,
     get_current_web_service_request,
@@ -253,7 +254,7 @@
 
 
 @implementer(IHTTPResource)
-class RedirectResource:
+class RedirectResource(URLDereferencingMixin):
     """A resource that redirects to another URL."""
 
     def __init__(self, url, request):
@@ -265,6 +266,10 @@
         self.request.response.setStatus(301)
         self.request.response.setHeader("Location", url)
 
+    @property
+    def context(self):
+        return self.dereference_url_as_object(self.url)
+
 
 @implementer(IHTTPResource)
 class HTTPResource:
 
=== modified file 'src/lazr/restful/docs/webservice-marshallers.rst'
--- src/lazr/restful/docs/webservice-marshallers.rst	2020-02-04 11:52:59 +0000
+++ src/lazr/restful/docs/webservice-marshallers.rst	2020-06-30 15:58:27 +0000
@@ -705,6 +705,19 @@
     >>> print(cookbook.name)
     Everyday Greens
 
+Redirections
+~~~~~~~~~~~~
+
+Objects may have multiple URLs, with non-canonical forms redirecting to
+canonical forms.  The object marshaller accepts URLs that redirect, provided
+that the redirected-to resource knows how to find the ultimate target
+object.
+
+    >>> cookbook = reference_marshaller.marshall_from_json_data(
+    ...     '/cookbooks/featured')
+    >>> print(cookbook.name)
+    Mastering the Art of French Cooking
+
 Collections
 -----------
 
 
=== modified file 'src/lazr/restful/marshallers.py'
--- src/lazr/restful/marshallers.py	2020-02-04 13:17:32 +0000
+++ src/lazr/restful/marshallers.py	2020-06-30 15:58:27 +0000
@@ -82,10 +82,11 @@
         else:
             site_protocol = 'http'
             default_port = '80'
-        request_host = self.request.get('HTTP_HOST', 'localhost')
-        if ':' in request_host:
-            request_host, request_port = request_host.split(':', 2)
+        full_request_host = self.request.get('HTTP_HOST', 'localhost')
+        if ':' in full_request_host:
+            request_host, request_port = full_request_host.split(':', 2)
         else:
+            request_host = full_request_host
             request_port = default_port
 
         if not isinstance(url, basestring):
@@ -116,11 +117,32 @@
         path_parts = [unquote(part) for part in path.split('/')]
         path_parts.pop(0)
         path_parts.reverse()
-        request = config.createRequest(StringIO(), {'PATH_INFO': path})
+        environ = {'PATH_INFO': path, 'HTTP_HOST': full_request_host}
+        server_url = self.request.get('SERVER_URL')
+        if server_url is not None:
+            environ['SERVER_URL'] = server_url
+        request = config.createRequest(StringIO(), environ)
         request.setTraversalStack(path_parts)
         root = request.publication.getApplication(self.request)
         return request.traverse(root)
 
+    def dereference_url_as_object(self, url):
+        """Look up a data model object in the web service by URL."""
+        try:
+            resource = self.dereference_url(url)
+        except NotFound:
+            # The URL doesn't correspond to any real object.
+            raise ValueError(u'No such object "%s".' % url)
+        except InvalidURIError:
+            raise ValueError(u'"%s" is not a valid URI.' % url)
+        # We looked up the URL and got the thing at the other end of
+        # the URL: a resource. But internally, a resource isn't a
+        # valid value for any schema field. Instead we want the object
+        # that serves as a resource's context. Any time we want to get
+        # to the object underlying a resource, we need to strip its
+        # security proxy.
+        return removeSecurityProxy(resource).context
+
 
 @implementer(IFieldMarshaller)
 class SimpleFieldMarshaller:
@@ -633,17 +655,4 @@
 
         Look up the data model object by URL.
         """
-        try:
-            resource = self.dereference_url(value)
-        except NotFound:
-            # The URL doesn't correspond to any real object.
-            raise ValueError(u'No such object "%s".' % value)
-        except InvalidURIError:
-            raise ValueError(u'"%s" is not a valid URI.' % value)
-        # We looked up the URL and got the thing at the other end of
-        # the URL: a resource. But internally, a resource isn't a
-        # valid value for any schema field. Instead we want the object
-        # that serves as a resource's context. Any time we want to get
-        # to the object underlying a resource, we need to strip its
-        # security proxy.
-        return removeSecurityProxy(resource).context
+        return self.dereference_url_as_object(value)