Tutorial

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from zope.interface import implements
from repoze.bfg.interfaces import IContextURL
from repoze.bfg.interfaces import VH_ROOT_KEY

from repoze.bfg.traversal import find_model
from repoze.bfg.traversal import find_root
from repoze.bfg.traversal import model_path

NON_VH_URL_KEY = 'HTTP_X_NON_VHM_URL'

class TraversalContextURL(object):
    """ The IContextURL adapter used to generate URLs for a context
    object obtained via graph traversal"""
    implements(IContextURL)

    vroot_varname = VH_ROOT_KEY
    non_vroot_varname = NON_VH_URL_KEY

    def __init__(self, context, request):
        self.context = context
        self.request = request

    def virtual_root(self):
        environ = self.request.environ
        vroot_varname = self.vroot_varname
        if vroot_varname in environ:
            return find_model(self.context, environ[vroot_varname])
        # shortcut instead of using find_root; we probably already
        # have it on the request
        try:
            return self.request.root
        except AttributeError:
            return find_root(self.context)
        
    def __call__(self):
        """ Generate a URL based on the :term:`lineage` of a
        :term:`model` object obtained via :term:`traversal`.  If any
        model in the context lineage has a Unicode name, it will be
        converted to a UTF-8 string before being attached to the URL.
        If a ``HTTP_X_VHM_ROOT`` key is present in the WSGI
        environment, its value will be treated as a 'virtual root
        path': the path of the URL generated by this will be
        left-stripped of this virtual root path value.
        """
        path = model_path(self.context)
        if path != '/':
            path = path + '/'
        request = self.request
        environ = request.environ
        vroot_varname = self.vroot_varname
        non_vroot_varname = self.non_vroot_varname

        app_url = request.application_url # never ends in a slash
        
        # if the path starts with the virtual root path, trim it out
        if vroot_varname in environ:
            vroot_path = environ[vroot_varname]
            if path.startswith(vroot_path):
                path = path[len(vroot_path):]
            elif non_vroot_varname in environ:
                # If an alternative domain is configured, use that
                app_url = environ[non_vroot_varname].rstrip('/') # never ends in a slash

        return app_url + path



#### tests ####

from repoze.bfg.tests.test_traversal import TraversalContextURLTests as BFGTraversalContextURLTests
from repoze.bfg.tests.test_traversal import DummyContext, DummyRequest

class TraversalContextURLTests(BFGTraversalContextURLTests):
    def _getTargetClass(self):
        return TraversalContextURL

    def test_call_outside_vroot_no_non_vhm_url(self):
        """ If the ``NON_VH_URL_KEY`` var is not set, the original
            behaviour should remain.
        """
        from repoze.bfg.interfaces import VH_ROOT_KEY
        root = DummyContext()
        root.__parent__ = None
        root.__name__ = None
        one = DummyContext()
        one.__parent__ = root
        one.__name__ = 'one'
        two = DummyContext()
        two.__parent__ = one
        two.__name__ = 'two'
        three = DummyContext()
        three.__parent__ = root
        three.__name__ = 'three'
        request = DummyRequest({VH_ROOT_KEY:'/one'})
        context_url = self._makeOne(three, request)
        result = context_url()
        self.assertEqual(result, 'http://example.com:5432/three/')
        
        request = DummyRequest({VH_ROOT_KEY:'/one/two'})
        context_url = self._makeOne(three, request)
        result = context_url()
        self.assertEqual(result, 'http://example.com:5432/three/')

    def test_call_outside_vroot_with_non_vhm_url(self):
        """ If the ``NON_VH_URL_KEY`` var is set, any model_url()
            calls for objects located outside the vroot should use
            the configured url.
        """
        from repoze.bfg.interfaces import VH_ROOT_KEY
        root = DummyContext()
        root.__parent__ = None
        root.__name__ = None
        one = DummyContext()
        one.__parent__ = root
        one.__name__ = 'one'
        two = DummyContext()
        two.__parent__ = one
        two.__name__ = 'two'
        three = DummyContext()
        three.__parent__ = root
        three.__name__ = 'three'
        request = DummyRequest({VH_ROOT_KEY:'/one',
                                NON_VH_URL_KEY:'http://example.com:4321'})
        context_url = self._makeOne(three, request)
        result = context_url()
        self.assertEqual(result, 'http://example.com:4321/three/')
        
        context_url = self._makeOne(two, request)
        result = context_url()
        self.assertEqual(result, 'http://example.com:5432/two/')
        
        request = DummyRequest({VH_ROOT_KEY:'/one/two',
                                NON_VH_URL_KEY:'http://example.com:4321'})
        context_url = self._makeOne(three, request)
        result = context_url()
        self.assertEqual(result, 'http://example.com:4321/three/')
        
        context_url = self._makeOne(two, request)
        result = context_url()
        self.assertEqual(result, 'http://example.com:5432/')