Bug fixes, refactoring, and new features: * Container is gone; the framework now automatically detects containerness if you override handle_child or define sub-pages. So everything is now either a Page or a Form. * Trailing-'/' redirection now goes both ways, according to whether a page is a container or not. * Page.__init__ accepts keyword arguments to set class-defined attributes at creation. This is useful for containers that invoke dynamic subpages in handle_child(). * An extensible setup() method is provided for subclass-specific initialization, prior to go() being invoked. * Template expressions can now reference the module globals of the module where the template was created. * Pages can have a ``body`` attribute (a template or WSGI-return method) which will be invoked for GET requests. * HEAD requests are now only handled if GET is supported (i.e., if a ``body`` is defined), and the wrapping of GET is a bit cleaner. * If you define a ``db_connect()`` method returning a DBAPI connection object, you can use the ``query()`` method to do SQL queries, and your subpages will automatically "inherit" the database connection from their parent pages/container(s). Not bad for <550 lines!
"""Yet another WSGI micro-framework...""" import cgi, string, new, sys from wsgiref.util import shift_path_info, application_uri __all__ = [ "Page", "Form", "validator", "HTML", "Text", "Template", "HTTP", "EvalTemplate", "EvalMap", "Method", ] class Method(object): """Turn any object into a method""" def __init__(self, func): self.call = func def __get__(self, ob, typ=None): if ob is None: return self return new.instancemethod(self.call, ob, typ) class HTTP(Method): """Wrapper/decorator that marks an object as an HTTP method""" cls_registry = "http_methods" def validator(func): """Decorator that marks an object as a registered validator""" func.cls_registry = "registered_validators" return func text_plain = ('Content-Type', 'text/plain') text_html = ('Content-Type', 'text/html') def get_module(): return sys._getframe(2).f_globals.get('__name__', __name__) sentinel = object() class EvalMap(object): """Object that translates from getitem->getattr""" def __init__(self, page, extra={}, module=__name__): self.page = page self.extra = dict(extra) # always copy, to allow mod by listcomps self.module = module def __setitem__(self, key, value): # needed for listcomp exprs! self.extra[key] = value def __delitem__(self, key): # needed for listcomp exprs! del self.extra[key] def __getitem__(self, key): if key.startswith('(?'): return eval( key[2:].rstrip(')').rstrip('?').strip(), sys.modules[self.module].__dict__, self ) elif key in self.extra: return self.extra[key] else: ob = getattr(self.page, key, sentinel) if ob is not sentinel: return ob g = sys.modules[self.module].__dict__ if key in g: return g[key] if key=='self': return self raise KeyError class EvalTemplate(string.Template): idpattern = r'[_a-z][_a-z0-9]*|\(\?[^?]*\?\)' class Text(Method): """Text template w/string substitution that can be used as a method Note: templates cannot be directly invoked from the web unless they are created with Text.page() or Text.http_method(), or used as a Page's ``body`` attribute. """ cls_registry = None factory = EvalTemplate status = '200 OK' headers = text_plain, resource = caller = None def __init__(self, *args, **kw): kw.setdefault('caller', get_module()) for k, v in kw.items(): if hasattr(type(self),k): setattr(self, k, v) del kw[k] if self.resource: self.options = kw else: self.template = self.factory(*args, **kw) def call(self, page, extra_headers = [], **kw): content = self.render(page, kw) headers = list(self.headers) + extra_headers headers.append(('Content-Length',str(len(content)))) page.start_response(self.status, headers) return [content] def render(self, page, kw={}): if self.resource: from pkg_resources import resource_string body = resource_string(self.caller, self.resource) self.template = self.factory(body, **self.options) self.resource = None return self.template.substitute(EvalMap(page, kw, self.caller)) @classmethod def fragment(cls, *args, **kw): """Template property that returns its rendered body""" return property(cls(caller = get_module(), *args, **kw).render) @classmethod def http_method(cls, *args, **kw): """Template that can be used as an HTTP method (GET, POST, PUT, etc.)""" return cls( caller=get_module(), cls_registry='http_methods', *args, **kw ) @classmethod def method(cls, *args, **kw): """Template method that can be called with keyword arguments""" return Method(cls(caller = get_module(), *args, **kw).render) @classmethod def page(cls, *args, **kw): """Template sub-page (returns a Page subclass w/template as its body) If you supply a `type` keyword argument, that type is used as the base class for the page. The other arguments are used to create the template to be used as the returned class' ``body`` attribute. """ caller = get_module() class _Page(kw.get('type',Page)): body = cls(caller=caller, *args, **kw) return _Page class HTML(Text): """HTML template w/string substitution that can be used as a method Note: templates cannot be directly invoked from the web unless they are created with HTML.page() or HTML.http_method(), or used as a Page's ``body`` attribute. """ headers = text_html, class Template(HTML): """TurboGears/Buffet template that can be used as a method Note: templates cannot be directly invoked from the web unless they are created with Template.page() or Template.http_method(), or used as a Page's ``body`` attribute. """ engine = None resource = property(lambda self:None) # resources can't be used for this def factory(self, templatename, **options): engine, name = templatename.split(':', 1) from pkg_resources import iter_entry_points for ep in iter_entry_points('python.templating.engines',engine): self.engine = ep.load()() break else: raise RuntimeError("Template engine %r is not installed" % (engine,)) return name def render(self, page, kw={}): return self.engine.render( EvalMap(page,kw,self.caller), template=self.template ) class Page(object): """A generic web location""" cls_registry = "sub_pages" http_methods = [] sub_pages = [] body = None class __metaclass__(type): def __init__(cls, name, bases, cdict): for k in dir(cls): v = getattr(cls, k) reg = getattr(v, 'cls_registry', None) if reg: d = cdict.setdefault(reg,[]) d.append(k) setattr(cls, reg, d) def __call__(cls, *args, **kw): self = type.__call__(cls, *args, **kw) return self.go() def __init__(self, environ, start_response, **kw): self.environ = environ self.start_response = start_response cls = type(self) for k, v in kw.items(): getattr(cls,k) # AttributeError here means bad keyword arg setattr(self,k,v) self.setup() # perform any dynamic initialization def invoke_method(self): rm = self.environ['REQUEST_METHOD'] if rm=='GET' and self.body is not None: return self.body() if rm=='HEAD' or rm in self.http_methods: return getattr(self, rm)() return self.METHOD_NOT_ALLOWED( [('Allow', ', '.join(self.http_methods))] ) def HEAD(self): environ['REQUEST_METHOD'] = 'GET' resp = iter(self.invoke_method()) # forward to 'GET' list(resp) # questionable hack to exhaust the response return resp # ensure that .close() gets called, if any def go(self): name = shift_path_info(self.environ) if name: return self.handle_child(name) url = application_uri(self.environ).rstrip('/') leaf = not self.sub_pages and type(self).handle_child == Page.handle_child if name=='': # trailing / if not leaf: return self.invoke_method() elif name is None: # no trailing / if leaf: return self.invoke_method() url += '/' # add the trailing / return self.redirect(url) def handle_child(self, name): if name in self.sub_pages: return getattr(self, name)( self.environ, self.start_response, parent=self ) return self.NOT_FOUND() def redirect(self, url): return self.REDIRECT_TO([('Location', url)], url=url) def setup(self): self.errors = [] self.db = getattr(self.parent, 'db', None) parent = None METHOD_NOT_ALLOWED = Text( "Excellent method!\n" "Alas, my response must be:\n" '"I cannot comply."', status="405 Method not allowed", ) REDIRECT_TO = HTML( '<html><head>' '<meta http-equiv="refresh" content="0;url=$url" />' '</head><body><a href="$url">Click here</a></body></html>', status='302 Found', ) NOT_FOUND = Text( "404 not found\n" "You deserve a kinder note\n" "Than this web haiku!\n", status = '404 Not Found', ) db = None # DBAPI database connection object def db_connect(self): """Override this in a subclass to return a DBAPI connection object""" raise NotImplementedError def query(self, *args, **kw): """Create and return a cursor (after optionally running a query on it) If positional arguments are supplied, they're passed to the cursor's ``execute()`` method. If keyword arguments are supplied, they are used to set cursor attributes prior to the ``execute()`` (if applicable). """ db = self.db if db is None: db = self.db = self.db_connect() cursor = db.cursor() for k, v in kw.items(): setattr(cursor, k, v) if args: cursor.execute(*args) return cursor class Form(Page): """A page with POST processing, form parsing, validation, etc.""" registered_validators = [] data = {} defaults = {} def get_validators(self): return self.registered_validators def validate(self): for k in self.get_validators(): response = getattr(self,k)() if response: return response def __getattr__(self, name): if not name.startswith('__'): try: return self.data[name].value except KeyError: if name in self.defaults: return self.defaults[name] raise AttributeError(name) succeed = Text("Oops. Someone forgot to create a form or method here.") body = succeed # you should replace this with the form's template def parse(self): self.data = cgi.FieldStorage( self.environ['wsgi.input'], environ=self.environ ) errors_found = HTML.fragment( '<ul class="form_errors"><li class="form_error">' r'$(? "</li><li class=\"form_error\">".join(errors) ?)' '</li></ul>' ) show_errors = property(lambda self: self.errors and self.errors_found or '') @HTTP def POST(self): self.parse() response = self.validate() if response: return response elif self.errors: return self.fail() else: return self.succeed() # A miserably inadequate attempt at a decent UI... fail = HTML( "<html><head>" "<title>Sorry, we couldn't process your request</title></head>\n<body>" "<h2>Sorry, we couldn't process your request</h2>\n" "<p>We encountered some difficulties with your input:</p>" "$errors_found\n" "<p>If you would please use your browser's BACK button to go back and " "correct these problems, we'd appreciate it. Thanks for your help!" "</p></body>" ) class TestForm(Form): """A stupid example to test the framework""" defaults = dict(name='Joey', animal='Dog', email='joe@dog.com') body = fail = HTML("""<?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head><title>What is your favorite animal ?</title></head> <body> $show_errors <form method="post"> <table> <tr><td>What is your name ?</td> <td><input type="text" name="name" value="$(?cgi.escape(name)?)"/></td></tr> <tr><td>What is your favorite animal ?</td> <td><input type="text" name="animal" value="$(?cgi.escape(animal)?)"/></td></tr> <tr><td>What is your email address ?</td> <td><input type="text" name="email" value="$(?cgi.escape(email)?)"/></td></tr> <tr><td colspan="2"><input type="submit" /></td></tr> </table> </form> </body> </html> """) succeed = Text("Hey Joe!") @validator def check_joe(self): if self.name!='Joe': self.errors.append("Hey, you're not Joe!") errors_found = HTML.fragment( "<p>Please correct the following problems:</p>" '<ul class="form_errors"><li class="form_error">' r'$(? "</li><li class=\"form_error\">".join(errors) ?)' '</li></ul>' ) class TestContainer(Page): body = HTML("""<?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head><title>Silly test of WebHaiku</title></head> <body> <ul><li><a href="a">Hello world</a></li><li><a href="b">Hello Joe</a></li> <li><a href="c">Subcontainer</a></li> </ul> </body></html>""") a = Text.page("Hello world!") b = TestForm c = Page # placeholder TestContainer.c = TestContainer # allow some depth to the test...
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