# -*- test-case-name: twisted.web.test.test_web -*- # # Copyright (c) 2001-2004 Twisted Matrix Laboratories. # See LICENSE for details. """I hold the lowest-level Resource class.""" # System Imports from twisted.internet import defer from twisted.python import roots, components, reflect from zope.interface import Attribute, implements class IResource(components.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(self, 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(self, path, child): """Put a child IResource implementor at the given path. """ def render(self, 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("") to write data to the request, and request.finish() to send the data to the browser. """ 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 error.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 self.children.has_key(path): return self.children[path] return self.getChild(path, request) def getChildForRequest(self, request): import warnings 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: from twisted.web.server import UnsupportedMethod raise UnsupportedMethod(getattr(self, '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) components.backwardsCompatImplements(Resource) #t.w imports #This is ugly, I know, but since error.py directly access resource.Resource #during import-time (it subclasses it), the Resource class must be defined #by the time error is imported. import error