def find_resource(resource, path):
""" Given a resource object and a string or tuple representing a path
(such as the return value of :func:`pyramid.traversal.resource_path` or
:func:`pyramid.traversal.resource_path_tuple`), return a resource in this
application's resource tree at the specified path. The resource passed
in *must* be :term:`location`-aware. If the path cannot be resolved (if
the respective node in the resource tree does not exist), a
:exc:`KeyError` will be raised.
This function is the logical inverse of
:func:`pyramid.traversal.resource_path` and
:func:`pyramid.traversal.resource_path_tuple`; it can resolve any
path string or tuple generated by either of those functions.
Rules for passing a *string* as the ``path`` argument: if the
first character in the path string is the ``/``
character, the path is considered absolute and the resource tree
traversal will start at the root resource. If the first character
of the path string is *not* the ``/`` character, the path is
considered relative and resource tree traversal will begin at the resource
object supplied to the function as the ``resource`` argument. If an
empty string is passed as ``path``, the ``resource`` passed in will
be returned. Resource path strings must be escaped in the following
manner: each Unicode path segment must be encoded as UTF-8 and as
each path segment must escaped via Python's :mod:`urllib.quote`.
For example, ``/path/to%20the/La%20Pe%C3%B1a`` (absolute) or
``to%20the/La%20Pe%C3%B1a`` (relative). The
:func:`pyramid.traversal.resource_path` function generates strings
which follow these rules (albeit only absolute ones).
Rules for passing *text* (Unicode) as the ``path`` argument are the same
as those for a string. In particular, the text may not have any nonascii
characters in it.
Rules for passing a *tuple* as the ``path`` argument: if the first
element in the path tuple is the empty string (for example ``('',
'a', 'b', 'c')``, the path is considered absolute and the resource tree
traversal will start at the resource tree root object. If the first
element in the path tuple is not the empty string (for example
``('a', 'b', 'c')``), the path is considered relative and resource tree
traversal will begin at the resource object supplied to the function
as the ``resource`` argument. If an empty sequence is passed as
``path``, the ``resource`` passed in itself will be returned. No
URL-quoting or UTF-8-encoding of individual path segments within
the tuple is required (each segment may be any string or unicode
object representing a resource name). Resource path tuples generated by
:func:`pyramid.traversal.resource_path_tuple` can always be
resolved by ``find_resource``.
.. note:: For backwards compatibility purposes, this function can also
be imported as :func:`pyramid.traversal.find_model`, although doing so
will emit a deprecation warning.
"""
if isinstance(path, text_type):
path = ascii_native_(path)
D = traverse(resource, path)
view_name = D['view_name']
context = D['context']
if view_name:
raise KeyError('%r has no subelement %s' % (context, view_name))
return context
def traverse(resource, path):
"""Given a resource object as ``resource`` and a string or tuple
representing a path as ``path`` (such as the return value of
:func:`pyramid.traversal.resource_path` or
:func:`pyramid.traversal.resource_path_tuple` or the value of
``request.environ['PATH_INFO']``), return a dictionary with the
keys ``context``, ``root``, ``view_name``, ``subpath``,
``traversed``, ``virtual_root``, and ``virtual_root_path``.
A definition of each value in the returned dictionary:
- ``context``: The :term:`context` (a :term:`resource` object) found
via traversal or url dispatch. If the ``path`` passed in is the
empty string, the value of the ``resource`` argument passed to this
function is returned.
- ``root``: The resource object at which :term:`traversal` begins.
If the ``resource`` passed in was found via url dispatch or if the
``path`` passed in was relative (non-absolute), the value of the
``resource`` argument passed to this function is returned.
- ``view_name``: The :term:`view name` found during
:term:`traversal` or :term:`url dispatch`; if the ``resource`` was
found via traversal, this is usually a representation of the
path segment which directly follows the path to the ``context``
in the ``path``. The ``view_name`` will be a Unicode object or
the empty string. The ``view_name`` will be the empty string if
there is no element which follows the ``context`` path. An
example: if the path passed is ``/foo/bar``, and a resource
object is found at ``/foo`` (but not at ``/foo/bar``), the 'view
name' will be ``u'bar'``. If the ``resource`` was found via
urldispatch, the view_name will be the name the route found was
registered with.
- ``subpath``: For a ``resource`` found via :term:`traversal`, this
is a sequence of path segments found in the ``path`` that follow
the ``view_name`` (if any). Each of these items is a Unicode
object. If no path segments follow the ``view_name``, the
subpath will be the empty sequence. An example: if the path
passed is ``/foo/bar/baz/buz``, and a resource object is found at
``/foo`` (but not ``/foo/bar``), the 'view name' will be
``u'bar'`` and the :term:`subpath` will be ``[u'baz', u'buz']``.
For a ``resource`` found via url dispatch, the subpath will be a
sequence of values discerned from ``*subpath`` in the route
pattern matched or the empty sequence.
- ``traversed``: The sequence of path elements traversed from the
root to find the ``context`` object during :term:`traversal`.
Each of these items is a Unicode object. If no path segments
were traversed to find the ``context`` object (e.g. if the
``path`` provided is the empty string), the ``traversed`` value
will be the empty sequence. If the ``resource`` is a resource found
via :term:`url dispatch`, traversed will be None.
- ``virtual_root``: A resource object representing the 'virtual' root
of the resource tree being traversed during :term:`traversal`.
See :ref:`vhosting_chapter` for a definition of the virtual root
object. If no virtual hosting is in effect, and the ``path``
passed in was absolute, the ``virtual_root`` will be the
*physical* root resource object (the object at which :term:`traversal`
begins). If the ``resource`` passed in was found via :term:`URL
dispatch` or if the ``path`` passed in was relative, the
``virtual_root`` will always equal the ``root`` object (the
resource passed in).
- ``virtual_root_path`` -- If :term:`traversal` was used to find
the ``resource``, this will be the sequence of path elements
traversed to find the ``virtual_root`` resource. Each of these
items is a Unicode object. If no path segments were traversed
to find the ``virtual_root`` resource (e.g. if virtual hosting is
not in effect), the ``traversed`` value will be the empty list.
If url dispatch was used to find the ``resource``, this will be
``None``.
If the path cannot be resolved, a :exc:`KeyError` will be raised.
Rules for passing a *string* as the ``path`` argument: if the
first character in the path string is the with the ``/``
character, the path will considered absolute and the resource tree
traversal will start at the root resource. If the first character
of the path string is *not* the ``/`` character, the path is
considered relative and resource tree traversal will begin at the resource
object supplied to the function as the ``resource`` argument. If an
empty string is passed as ``path``, the ``resource`` passed in will
be returned. Resource path strings must be escaped in the following
manner: each Unicode path segment must be encoded as UTF-8 and
each path segment must escaped via Python's :mod:`urllib.quote`.
For example, ``/path/to%20the/La%20Pe%C3%B1a`` (absolute) or
``to%20the/La%20Pe%C3%B1a`` (relative). The
:func:`pyramid.traversal.resource_path` function generates strings
which follow these rules (albeit only absolute ones).
Rules for passing a *tuple* as the ``path`` argument: if the first
element in the path tuple is the empty string (for example ``('',
'a', 'b', 'c')``, the path is considered absolute and the resource tree
traversal will start at the resource tree root object. If the first
element in the path tuple is not the empty string (for example
``('a', 'b', 'c')``), the path is considered relative and resource tree
traversal will begin at the resource object supplied to the function
as the ``resource`` argument. If an empty sequence is passed as
``path``, the ``resource`` passed in itself will be returned. No
URL-quoting or UTF-8-encoding of individual path segments within
the tuple is required (each segment may be any string or unicode
object representing a resource name).
Explanation of the conversion of ``path`` segment values to
Unicode during traversal: Each segment is URL-unquoted, and
decoded into Unicode. Each segment is assumed to be encoded using
the UTF-8 encoding (or a subset, such as ASCII); a
:exc:`pyramid.exceptions.URLDecodeError` is raised if a segment
cannot be decoded. If a segment name is empty or if it is ``.``,
it is ignored. If a segment name is ``..``, the previous segment
is deleted, and the ``..`` is ignored. As a result of this
process, the return values ``view_name``, each element in the
``subpath``, each element in ``traversed``, and each element in
the ``virtual_root_path`` will be Unicode as opposed to a string,
and will be URL-decoded.
"""
if is_nonstr_iter(path):
# the traverser factory expects PATH_INFO to be a string, not
# unicode and it expects path segments to be utf-8 and
# urlencoded (it's the same traverser which accepts PATH_INFO
# from user agents; user agents always send strings).
if path:
path = _join_path_tuple(tuple(path))
else:
path = ''
# The user is supposed to pass us a string object, never Unicode. In
# practice, however, users indeed pass Unicode to this API. If they do
# pass a Unicode object, its data *must* be entirely encodeable to ASCII,
# so we encode it here as a convenience to the user and to prevent
# second-order failures from cropping up (all failures will occur at this
# step rather than later down the line as the result of calling
# ``traversal_path``).
path = ascii_native_(path)
if path and path[0] == '/':
resource = find_root(resource)
reg = get_current_registry()
request_factory = reg.queryUtility(IRequestFactory)
if request_factory is None:
from pyramid.request import Request # avoid circdep
request_factory = Request
request = request_factory.blank(path)
request.registry = reg
traverser = reg.queryAdapter(resource, ITraverser)
if traverser is None:
traverser = ResourceTreeTraverser(resource)
return traverser(request)
