Does Flask support regular expressions in its URL routing?

Question

I understand that Flask has the int, float and path converters, but the application we're developing has more complex patterns in its URLs.

Is there a way we can use regular expressions, as in Django?

Answer 1

Even though Armin beat me to the punch with an accepted answer I thought I'd show an abbreviated example of how I implemented a regex matcher in Flask just in case anyone wants a working example of how this could be done.

from flask import Flask from werkzeug.routing import BaseConverter  app = Flask(__name__)  class RegexConverter(BaseConverter):     def __init__(self, url_map, *items):         super(RegexConverter, self).__init__(url_map)         self.regex = items[0]   app.url_map.converters['regex'] = RegexConverter  @app.route('/<regex("[abcABC0-9]{4,6}"):uid>-<slug>/') def example(uid, slug):     return "uid: %s, slug: %s" % (uid, slug)   if __name__ == '__main__':     app.run(debug=True, host='0.0.0.0', port=5000) 

this URL should return with 200: http://localhost:5000/abc0-foo/

this URL should will return with 404: http://localhost:5000/abcd-foo/

Answer 2

You can hook in custom converters that match for arbitrary expressions: Custom Converter

from random import randrange from werkzeug.routing import Rule, Map, BaseConverter, ValidationError  class BooleanConverter(BaseConverter):      def __init__(self, url_map, randomify=False):         super(BooleanConverter, self).__init__(url_map)         self.randomify = randomify         self.regex = '(?:yes|no|maybe)'      def to_python(self, value):         if value == 'maybe':             if self.randomify:                 return not randrange(2)             raise ValidationError()         return value == 'yes'      def to_url(self, value):         return value and 'yes' or 'no'  url_map = Map([     Rule('/vote/<bool:werkzeug_rocks>', endpoint='vote'),     Rule('/vote/<bool(randomify=True):foo>', endpoint='foo') ], converters={'bool': BooleanConverter})