Routes TODO

Updated 2009-09-07

Planned changes


Backport the Route and Mapper refactorings from Routes-experimental (formerly called Routes 2). Make the objects more introspection-friendly. Add a generation dict for named routes; this will help both efficiency and introspection.

Generating the current URL with a modified query string

When url.current() generates the current URL, it omits the existing query string. Any keyword args passed override path variables or set new query parameters. Extracting the existing query string from the request is tedious, especially if you want to modify some parameters.

A new method url.current_with_query() will generate the current URL with its query string. Any keyword args add or override query parameters. An argument with a value None deletes that parameter if it exists, so that it will not be in the generated URL. There will be no way to change path variables in the URL.

Positional arguments will be appended to the URL path using urljoin.

Options for generating a fully-qualified URL will be retained. The option _fragment specifies a URL fragment (“#fragment”).

Failure routes

A method fail for causing 4xx and 5xx errors. This is akin to .redirect for 3xx errors.

A convenience method gone may also be added for 410 errors. This indicates that the URL has been deleted and should be removed from bookmarks and search engines. These will be called “gone routes”.

Chaining to WSGI applications

A connect argument wsgi_app for chaining to another WSGI application. This would allow a Pylons app to chain to other applications directly in the route map rather than having to create dummy controllers for them.

Users would have to put “{path_info:.*}” at the end of the path to indicate which part of the URL should be passed to the application. This raises multiple issues:

  • Users would prefer to specify a URL prefix rather than a URL with a path_info variable. But this is incompatible with Routes matching. One could create a special kind of route with a different method, such as map.chain, but that would raise as many issues as it solves, such as the need to duplicate all the route options in the second method.
  • What about the sub-application’s home page? I.e., PATH_INFO=/ . This can be handled by changing an empty path_info variable to “/”, but what if the route does not want a path_info variable in the path?

New route creation method

Add a new mapper method add with a stricter syntax for creating routes. (The existing connect method will remain at least in all 1.x versions.)

map.add(name, path, variables=None, match=True, requirements=None,
    if_match=None, if_function=None, if_subdomain=None, if_method=None,

The first argument, name is required. It should be a string name, or None for unnamed routes. (This syntax is also allowed by connect for forward compatibility.) This eliminates the “moving argument” situation where the path argument changes position depending on whether a name is specified. This will make it easier to read a list of route definitions aligned vertically, encourage named routes, and make unnamed routes obvious.

The second argument, path, is unchanged.

The third argument, variables, is for extra variables. These will be passed as a dict rather than as keyword args. This will make a clear distinction between variables and route options, and allow options to have more intuitive names without risk of collision, and without leading underscores. New applications can use either the {} or dict() syntax; old applications can simply put dict() around existing keyword args. If no extra variables are required you can pass an empty dict, None, or omit the argument.

The fourth argument, match, is true if the route is for both matching and generation, or false for generation only. The default is true. Whea converting from connect, change _static=True to match=False.

The remaining options should be set only via keyword arguments because their positions might change.

The requirements option is unchanged.

if_function corresponds to the function condition in connect. The value is unchanged.

if_subdomain corresponds to the subdomain condition in connect. The value is unchanged.

if_method corresponds to the method condition in connect. The value is unchanged.

generate_filter corresponds to the filter argument to connect. The value is unchanged.

One problem is that users might expect this syntax in the redirect method (and fail when it’s added), but redirect can’t be changed due to backward compatibility. Although some of these options may not make sense for redirect and failure routes anyway. fail is not so much an issue because it doesn’t exist yet, so it doesn’t matter if it’s added with the new syntax.

Resource routes

Add a second kind of resource route with the traditional add-modify-delete paradigm using only GET and POST, where each GET URL displays a form and the same POST URL processes it. This is non-RESTful but useful in interactive applications that don’t really need the other methods, and avoids doubling up dissimilar behavior onto the same URL. The method should also have add=True, edit=True, delete=True arguments to disable services which will not be implemented (e.g., resources that can’t be deleted, or are added outside the web interface). This would be under a different method, hopefully called something better than .resource2.

Slimmed-down package

Make a slimmed-down version of Routes without deprecated features. This can be kept as a separate branch or repository, and uploaded to PyPI under Routes with a different filename; e.g., Routes-NC.

Under consideration

Route group

When adding a group of routes such as a resource, keep the group identity for introspection. Currently the routes are added individually and lose their groupness. This could be done with a RouteGroup collection in the matchlist which delegates to its sub-routes. This would not apply to named generation, which needs a single dict of route names.

Required variables

A mapper constructor arg listing the variables all routes must have in their path or extra variables. Defining a route without these variables would raise an error. Intended for “controller” and “action” variables in frameworks like Pylons. However, there are cases where normally-required variables would be omitted, such as chaining to another WSGI application (in which case “controller” would be necessary but not “action”). Of course, the route can always define action=None.