Document wild card filters with named groups, possible feature improvement

[oz123]

I wanted to use wild card pattern with named groups, this was surprisingly easy, even thought the example in the docs is very terse.

As an example, consider the following:

from pypiserver.bottle import Bottle, run

def project_version_filter(config):
    pattern = r"(?P<project>.*)-(?P<version>.*)-(?P<constraints>.*-.*-.*)\.whl\.metadata$"

    def to_python(match):
        """
        >>> "bottle-0.13.2-py2.py3-none-any.whl.metadata".split("-",2)
        ['bottle', '0.13.2', 'py2.py3-none-any.whl.metadata']
        """
        return match.split("-", 2)
    
    def to_url(value):
        return f"{value['project']}-{value['version']}-{value['constraints']}.whl.metadata"

    return pattern, to_python, to_url

app = Bottle()
app.router.add_filter('project_version', project_version_filter)

@app.route("/packages/<pkg:project_version>")
def serve_metadata(pkg, project, version, constraints):
    return locals() 


if __name__ == '__main__':
    run(app, reload=True, debug=True)

This works suprisingly well. However, there is small annoyance in the API. I must also pass the filter key.

def serve_metadata(pkg, project, version, constraints)

I patched bottle in the following way to allow a slightly more comfortable API which does not require passing the key,

e.g. the filter now injects only the groups to the function:

@app.route("/packages/<pkg:project_version>")
def serve_metadata(project, version, constraints):
    return locals() 

The complete app:

app = Bottle()
app.config["skip_filter_key"] = True
app.router.add_filter('project_version', project_version_filter)

@app.route("/packages/<pkg:project_version>")
def serve_metadata(project, version, constraints):
    return locals() 

The patch:

diff --git a/bottle.py b/bottle.py
index 8348da6..d9aaab9 100644
--- a/pypiserver/bottle.py
+++ b/pypiserver/bottle.py
@@ -359,7 +359,7 @@ class Router(object):
         if offset <= len(rule) or prefix:
             yield prefix + rule[offset:], None, None
 
-    def add(self, rule, method, target, name=None):
+    def add(self, rule, method, target, name=None, skip_filter_key=False):
         """ Add a new rule or replace the target for an existing rule. """
         anons = 0  # Number of anonymous wildcards found
         keys = []  # Names of keys
@@ -377,6 +377,9 @@ class Router(object):
                     pattern += '(?:%s)' % mask
                     key = 'anon%d' % anons
                     anons += 1
+                if skip_filter_key:
+                    pattern += '(%s)' % mask
+                    keys.append(key)
                 else:
                     pattern += '(?P<%s>%s)' % (key, mask)
                     keys.append(key)
@@ -400,8 +403,7 @@ class Router(object):
         except re.error as e:
             raise RouteSyntaxError("Could not add Route: %s (%s)" % (rule, e))
 
-        if filters:
-
+        if filters and not skip_filter_key:
             def getargs(path):
                 url_args = re_match(path).groupdict()
                 for name, wildcard_filter in filters:
@@ -506,7 +508,7 @@ class Route(object):
                  skiplist=None, **config):
         #: The application this route is installed to.
         self.app = app
-        #: The path-rule string (e.g. ``/wiki/<page>``).
+        #: The path-rule st/sring (e.g. ``/wiki/<page>``).
         self.rule = rule
         #: The HTTP method as a string (e.g. ``GET``).
         self.method = method
@@ -868,7 +870,11 @@ class Bottle(object):
         """ Add a route object, but do not change the :data:`Route.app`
             attribute."""
         self.routes.append(route)
-        self.router.add(route.rule, route.method, route, name=route.name)
+        self.router.add(route.rule,
+                        route.method,
+                        route,
+                        name=route.name,
+                        skip_filter_key=self.config.get("skip_filter_key"))
         if DEBUG: route.prepare()
 
     def route(self,

Would you be interested in merging this?

[oz123]

One more note:

I only went down this path, because I could only do this in the route's regex:

@app.route("/packages/<pkg_version:re:(.*-.*)-.*-.*-.*\.whl\.metadata>")
def serve_metadata(pkg_version):
    pkg, version, _ = pkg_version.split("-", 2)
    return locals() 

Unfortunately, we can't use named groupes as with:

pattern ="(?P<project>.*)-(?P<version>.*)-(?P<constraints>.*-.*-.*)\.whl\.metadata$"
@app.route(f"/packages/<pkg_version:re:{pattern}")
def serve_metadata(pkg_version):
    pkg, version, _ = pkg_version.split("-", 2)
    return locals() 

as this would raise an exception:

Traceback (most recent call last):
  File "/home/oznt/Software/pypiserver/test.py", line 22, in <module>
    @app.route(f"/packages/<pkg_version:re:{pattern}")
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/oznt/Software/pypiserver/pypiserver/bottle.py", line 925, in decorator
    self.add_route(route)
  File "/home/oznt/Software/pypiserver/pypiserver/bottle.py", line 873, in add_route
    self.router.add(route.rule,
  File "/home/oznt/Software/pypiserver/pypiserver/bottle.py", line 404, in add
    raise RouteSyntaxError("Could not add Route: %s (%s)" % (rule, e))
pypiserver.bottle.RouteSyntaxError: Could not add Route: /packages/<pkg_version:re:(?P<project>.*)-(?P<version>.*)-(?P<constraints>.*-.*-.*)\.whl\.metadata$ (bad character in group name 'project)\\.\\*\\)\\-\\(\\?P(?P<version' at position 32)

My point is that it's worth documenting, even if only as an issue for the benefit of others.