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|
# -*- test-case-name: twisted.web.test.test_web -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Implementation of the lowest-level Resource class.
"""
import warnings
from zope.interface import Attribute, implements, Interface
from twisted.python.reflect import prefixedMethodNames
from twisted.web import http
class IResource(Interface):
"""
A web resource.
"""
isLeaf = Attribute(
"""
Signal if this IResource implementor is a "leaf node" or not. If True,
getChildWithDefault will not be called on this Resource.
""")
def getChildWithDefault(name, request):
"""
Return a child with the given name for the given request.
This is the external interface used by the Resource publishing
machinery. If implementing IResource without subclassing
Resource, it must be provided. However, if subclassing Resource,
getChild overridden instead.
"""
def putChild(path, child):
"""
Put a child IResource implementor at the given path.
"""
def render(request):
"""
Render a request. This is called on the leaf resource for
a request. Render must return either a string, which will
be sent to the browser as the HTML for the request, or
server.NOT_DONE_YET. If NOT_DONE_YET is returned,
at some point later (in a Deferred callback, usually)
call request.write("<html>") to write data to the request,
and request.finish() to send the data to the browser.
L{twisted.web.error.UnsupportedMethod} can be raised if the
HTTP verb requested is not supported by this resource.
"""
def getChildForRequest(resource, request):
"""
Traverse resource tree to find who will handle the request.
"""
while request.postpath and not resource.isLeaf:
pathElement = request.postpath.pop(0)
request.prepath.append(pathElement)
resource = resource.getChildWithDefault(pathElement, request)
return resource
class Resource:
"""
I define a web-accessible resource.
I serve 2 main purposes; one is to provide a standard representation for
what HTTP specification calls an 'entity', and the other is to provide an
abstract directory structure for URL retrieval.
"""
implements(IResource)
entityType = IResource
server = None
def __init__(self):
"""Initialize.
"""
self.children = {}
isLeaf = 0
### Abstract Collection Interface
def listStaticNames(self):
return self.children.keys()
def listStaticEntities(self):
return self.children.items()
def listNames(self):
return self.listStaticNames() + self.listDynamicNames()
def listEntities(self):
return self.listStaticEntities() + self.listDynamicEntities()
def listDynamicNames(self):
return []
def listDynamicEntities(self, request=None):
return []
def getStaticEntity(self, name):
return self.children.get(name)
def getDynamicEntity(self, name, request):
if not self.children.has_key(name):
return self.getChild(name, request)
else:
return None
def delEntity(self, name):
del self.children[name]
def reallyPutEntity(self, name, entity):
self.children[name] = entity
# Concrete HTTP interface
def getChild(self, path, request):
"""
Retrieve a 'child' resource from me.
Implement this to create dynamic resource generation -- resources which
are always available may be registered with self.putChild().
This will not be called if the class-level variable 'isLeaf' is set in
your subclass; instead, the 'postpath' attribute of the request will be
left as a list of the remaining path elements.
For example, the URL /foo/bar/baz will normally be::
| site.resource.getChild('foo').getChild('bar').getChild('baz').
However, if the resource returned by 'bar' has isLeaf set to true, then
the getChild call will never be made on it.
@param path: a string, describing the child
@param request: a twisted.web.server.Request specifying meta-information
about the request that is being made for this child.
"""
return NoResource("No such child resource.")
def getChildWithDefault(self, path, request):
"""
Retrieve a static or dynamically generated child resource from me.
First checks if a resource was added manually by putChild, and then
call getChild to check for dynamic resources. Only override if you want
to affect behaviour of all child lookups, rather than just dynamic
ones.
This will check to see if I have a pre-registered child resource of the
given name, and call getChild if I do not.
"""
if path in self.children:
return self.children[path]
return self.getChild(path, request)
def getChildForRequest(self, request):
warnings.warn("Please use module level getChildForRequest.", DeprecationWarning, 2)
return getChildForRequest(self, request)
def putChild(self, path, child):
"""
Register a static child.
You almost certainly don't want '/' in your path. If you
intended to have the root of a folder, e.g. /foo/, you want
path to be ''.
"""
self.children[path] = child
child.server = self.server
def render(self, request):
"""
Render a given resource. See L{IResource}'s render method.
I delegate to methods of self with the form 'render_METHOD'
where METHOD is the HTTP that was used to make the
request. Examples: render_GET, render_HEAD, render_POST, and
so on. Generally you should implement those methods instead of
overriding this one.
render_METHOD methods are expected to return a string which
will be the rendered page, unless the return value is
twisted.web.server.NOT_DONE_YET, in which case it is this
class's responsibility to write the results to
request.write(data), then call request.finish().
Old code that overrides render() directly is likewise expected
to return a string or NOT_DONE_YET.
"""
m = getattr(self, 'render_' + request.method, None)
if not m:
# This needs to be here until the deprecated subclasses of the
# below three error resources in twisted.web.error are removed.
from twisted.web.error import UnsupportedMethod
allowedMethods = (getattr(self, 'allowedMethods', 0) or
_computeAllowedMethods(self))
raise UnsupportedMethod(allowedMethods)
return m(request)
def render_HEAD(self, request):
"""
Default handling of HEAD method.
I just return self.render_GET(request). When method is HEAD,
the framework will handle this correctly.
"""
return self.render_GET(request)
def _computeAllowedMethods(resource):
"""
Compute the allowed methods on a C{Resource} based on defined render_FOO
methods. Used when raising C{UnsupportedMethod} but C{Resource} does
not define C{allowedMethods} attribute.
"""
allowedMethods = []
for name in prefixedMethodNames(resource.__class__, "render_"):
allowedMethods.append(name)
return allowedMethods
class ErrorPage(Resource):
"""
L{ErrorPage} is a resource which responds with a particular
(parameterized) status and a body consisting of HTML containing some
descriptive text. This is useful for rendering simple error pages.
@ivar template: A C{str} which will have a dictionary interpolated into
it to generate the response body. The dictionary has the following
keys:
- C{"code"}: The status code passed to L{ErrorPage.__init__}.
- C{"brief"}: The brief description passed to L{ErrorPage.__init__}.
- C{"detail"}: The detailed description passed to
L{ErrorPage.__init__}.
@ivar code: An integer status code which will be used for the response.
@ivar brief: A short string which will be included in the response body.
@ivar detail: A longer string which will be included in the response body.
"""
template = """
<html>
<head><title>%(code)s - %(brief)s</title></head>
<body>
<h1>%(brief)s</h1>
<p>%(detail)s</p>
</body>
</html>
"""
def __init__(self, status, brief, detail):
Resource.__init__(self)
self.code = status
self.brief = brief
self.detail = detail
def render(self, request):
request.setResponseCode(self.code)
request.setHeader("content-type", "text/html; charset=utf-8")
return self.template % dict(
code=self.code,
brief=self.brief,
detail=self.detail)
def getChild(self, chnam, request):
return self
class NoResource(ErrorPage):
"""
L{NoResource} is a specialization of L{ErrorPage} which returns the HTTP
response code I{NOT FOUND}.
"""
def __init__(self, message="Sorry. No luck finding that resource."):
ErrorPage.__init__(self, http.NOT_FOUND,
"No Such Resource",
message)
class ForbiddenResource(ErrorPage):
"""
L{ForbiddenResource} is a specialization of L{ErrorPage} which returns the
I{FORBIDDEN} HTTP response code.
"""
def __init__(self, message="Sorry, resource is forbidden."):
ErrorPage.__init__(self, http.FORBIDDEN,
"Forbidden Resource",
message)
__all__ = [
'IResource', 'getChildForRequest',
'Resource', 'ErrorPage', 'NoResource', 'ForbiddenResource']
|
