implemented generic redirection type (closes #35)

application.py

@@ -2,11 +2,29 @@
 import functools
 
 # third-party
+import werkzeug.routing.map
 import flask
 
 # internals
 import util
 
+class URLMap(werkzeug.routing.map.Map):
+
+    def remove_endpoint(self, endpoint):
+
+        rules = []
+        for rule in self._rules:
+            if rule.endpoint == endpoint:
+                rules.append(rule)
+
+        for rule in rules:
+            self._rules.remove(rule)
+
+        del(self._rules_by_endpoint[endpoint])
+
+        self._remap = True
+        self.update()
+
 class MenuMixin:
 
     def menu(self, name):
@@ -53,6 +71,8 @@ class Blueprint(flask.Blueprint, MenuMixin, BlockMixin):
 
 class Application(flask.Flask, MenuMixin, BlockMixin):
 
+    url_map_class = URLMap
+
     def __init__(self, *args, **kwargs):
 
         super().__init__(*args, **kwargs)

database.py

@@ -10,7 +10,8 @@ from application import app
 import util
 import rendering
 
-app.db = playhouse.db_url.connect(app.config['DATABASE'])
+# NOTE: autorollback is deprecated in most current release of peewee, but development is done with 3.15.0
+app.db = playhouse.db_url.connect(app.config['DATABASE'], autorollback=True)
 
 @app.before_request
 def db_connect():

main.py

@@ -3,6 +3,7 @@
 # builtins
 import math
 import datetime
+import functools
 
 # third-party
 import markupsafe
@@ -580,6 +581,76 @@ class CuratedArt(commenting.Commentable):
     text = markdown.MarkdownField(null=False, verbose_name='Text')
     #link = peewee.ForeignKeyField(ScoredLink, null=True)
 
+class PermaRedirect(admin.Administerable):
+
+    # WARNING: This entire class is hacky and might break with virtually any flask or werkzeug update
+
+    __cache__ = {} # collect simplified instances in memory, keyed by id
+    match_path = peewee.CharField(null=False, unique=True, verbose_name='Match path', help_text='The path to match (i.e. as it was in URL on the old site')
+    redirect_path = peewee.CharField(null=False, verbose_name='Redirect path', help_text='The path to redirect to')
+
+    @classmethod
+    def view(cls, mode='full', **kwargs):
+
+        if mode != 'full':
+            return super().view(mode=mode, **kwargs)
+
+        info = cls.__cache__[kwargs['id']]
+        return flask.redirect(info['redirect_path'])
+
+    @classmethod
+    def boot(cls):
+
+        try:
+
+            for instance in cls.select():
+                cls.__cache__[instance.id] = {'match_path': instance.match_path, 'redirect_path': instance.redirect_path}
+
+            cls.update_routes()
+
+        except Exception as e:
+            app.logger.warning('Could not initialize PermaRedirect cache.')
+
+    @classmethod
+    def update_routes(cls):
+
+        for id, item in cls.__cache__.items():
+
+            # this is a simplified version of add_url_rule's logic
+            endpoint = f'permaredirect-{id}'
+
+            if endpoint in app.url_map._rules_by_endpoint:
+                app.url_map.remove_endpoint(endpoint)
+
+            #app.add_url_rule(item['match_path'], endpoint, functools.partial(cls.view, mode='full', id=id))
+            rule = app.url_rule_class(item['match_path'], methods=('GET', 'OPTIONS'), endpoint=endpoint)
+            rule.provide_automatic_options = True
+
+            app.url_map.add(rule)
+            app.view_functions[endpoint] = functools.partial(cls.view, mode='full', id=id)
+
+    def save(self, **kwargs):
+
+        # NOTE/TODO: This is an ugly hack (but so is the rest of this class).
+        # Should™ (also) be checked/handled via form validation
+        for path in (self.match_path, self.redirect_path):
+            if '<' in path or '>' in path:
+                raise ValueError(f"PermaRedirect paths MUST NOT contain '<' or '>' but got: {path}")
+
+        super().save(**kwargs)
+
+        self.__class__.__cache__[self.id] = {'match_path': self.match_path, 'redirect_path': self.redirect_path}
+        self.__class__.update_routes()
+
+    def delete_instance(self, **kwargs):
+
+        del(self.__class__.__cache__[self.id])
+        self.__class__.update_routes()
+
+        super().delete_instance(**kwargs)
+
+app.boot(PermaRedirect.boot)
+
 app.boot_run()
 
 if __name__ == '__main__':

themes/default/templates/renderable/permaredirect.html

@@ -0,0 +1,10 @@
+{% extends 'default/templates/renderable/administerable.html' %}
+
+{% block content %}
+    <div>
+        <span>Match path:</span> <span class="match-path path">{{ content.match_path }}</span>
+    </div>
+    <div>
+        <span>Redirect path:</span> <span class="redirect-path path">{{ content.redirect_path }}</span>
+    </div>
+{% endblock %}