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Sample App with routes and route parameters
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| import re | |
| def extract_variables(endpoint: str): | |
| """ | |
| Very simple route "parsing" using regex: | |
| The route: | |
| "/item/{item_id}" | |
| becomes: | |
| [ | |
| ('string', '/item/'), | |
| ('variable', 'item_id'), | |
| ] | |
| """ | |
| parts = re.split(r'\{(\w+)\}', endpoint) # -> ["/item/", "item_id", ""] | |
| route_pieces = [] | |
| for i, part in enumerate(parts): | |
| if i % 2 == 0: | |
| route_pieces.append(('string', part)) | |
| else: | |
| route_pieces.append(('variable', part)) | |
| # if the last part was a variable, it still ends with one | |
| # empty ('string', '') part, that we just remove. | |
| if route_pieces[-1][1] == '': | |
| route_pieces.pop() | |
| return route_pieces | |
| class Route: | |
| """A simple route class""" | |
| def __init__(self, pattern: str, func): | |
| self.pattern = pattern | |
| self.func = func | |
| self._regex_pattern = re.compile(self._compile_as_regexp(pattern)) | |
| def _compile_as_regexp(self, pattern: str): | |
| """ | |
| A pattern like: "/item/{item_id}" | |
| becomes a regex like: "/item/(?P<item_id>[^/]+)" | |
| """ | |
| parts = extract_variables(pattern) | |
| regex_parts = [] | |
| for kind, part in parts: | |
| if kind == 'string': | |
| regex_parts.append(re.escape(part)) | |
| else: | |
| regex_parts.append(rf'(?P<{part}>[^/]+)') | |
| return '^' + ''.join(regex_parts) + '$' | |
| def matches(self, request_path: str): | |
| return self._regex_pattern.match(request_path) | |
| class App: | |
| """A simple App""" | |
| def __init__(self): | |
| self.routes = [] | |
| def get(self, pattern: str): | |
| def decorator(func): | |
| print('This is called immediately on function definition (not when the function is called).') | |
| self.routes.append(Route(pattern, func)) | |
| return func | |
| return decorator | |
| def match(self, request: str): | |
| """find a route that matches the request""" | |
| for route in self.routes: | |
| if m := route.matches(request): | |
| return route, m.groupdict() | |
| app = App() | |
| @app.get("/item/{item_id}") | |
| def get_item(item_id): | |
| print('hello. The item id is:', item_id) | |
| print('Routes have been registered:') | |
| print(app.routes) | |
| result = app.match('/item/123') | |
| if result: | |
| route, view_args = result | |
| route.func(**view_args) |
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