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# `virtualpathresolver` (`prefix`)

- Method of Environment
- New in Lektor Version 2.0

When implementing Virtual Source Objects it's important that you can locate them. While virtual sources do not appear as children of pages they can be navigated to through the database pad. This is achieved through custom virtual path resolvers.

Each source object needs to be a unique prefix which identifies all instances of it. For instance if you want to implement a special page (like a feed) that would exist for specific pages, then you can register the virtual path prefix `feed` with your plugin. Though you should use more descriptive names for your plugins as these paths are shared.

If a user then resolves the page `/my-page@feed` it would invoke your URL resolver with the record `my-page` and an empty list (rest of the path segments). If they would request `/my-page@feed/recent` then it would pass `['recent']` as path segments.

## Example

Here an example that would implement a virtual source for feeds and an associated virtual path resolver:

    from lektor.sourceobj import VirtualSourceObject
    from lektor.utils import build_url

    class Feed(VirtualSourceObject):

        def __init__(self, record, version='default'):
            VirtualSourceObject.__init__(self, record)
            self.version = version

        @property
        def path(self):
            return '%s@feed%s' % (
                self.record.path,
                '/' + self.version if self.version != 'default' else '',
            )

        @property
        def url_path(self):
            return build_url([self.record.url_path, 'feed.xml'])

    def on_setup_env(self, **extra):
        @self.env.virtualpathresolver('feed')
        def resolve_virtual_path(record, pieces):
            if not pieces:
                return Feed(record)
            elif pieces == ['recent']:
                return Feed(record, version='recent')

## Comments