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- from django.contrib.syndication.views import Feed as BaseFeed
- from django.utils.feedgenerator import Atom1Feed, Rss201rev2Feed
-
-
- class GeoFeedMixin:
- """
- This mixin provides the necessary routines for SyndicationFeed subclasses
- to produce simple GeoRSS or W3C Geo elements.
- """
-
- def georss_coords(self, coords):
- """
- In GeoRSS coordinate pairs are ordered by lat/lon and separated by
- a single white space. Given a tuple of coordinates, return a string
- GeoRSS representation.
- """
- return " ".join("%f %f" % (coord[1], coord[0]) for coord in coords)
-
- def add_georss_point(self, handler, coords, w3c_geo=False):
- """
- Adds a GeoRSS point with the given coords using the given handler.
- Handles the differences between simple GeoRSS and the more popular
- W3C Geo specification.
- """
- if w3c_geo:
- lon, lat = coords[:2]
- handler.addQuickElement("geo:lat", "%f" % lat)
- handler.addQuickElement("geo:lon", "%f" % lon)
- else:
- handler.addQuickElement("georss:point", self.georss_coords((coords,)))
-
- def add_georss_element(self, handler, item, w3c_geo=False):
- """Add a GeoRSS XML element using the given item and handler."""
- # Getting the Geometry object.
- geom = item.get("geometry")
- if geom is not None:
- if isinstance(geom, (list, tuple)):
- # Special case if a tuple/list was passed in. The tuple may be
- # a point or a box
- box_coords = None
- if isinstance(geom[0], (list, tuple)):
- # Box: ( (X0, Y0), (X1, Y1) )
- if len(geom) == 2:
- box_coords = geom
- else:
- raise ValueError("Only should be two sets of coordinates.")
- else:
- if len(geom) == 2:
- # Point: (X, Y)
- self.add_georss_point(handler, geom, w3c_geo=w3c_geo)
- elif len(geom) == 4:
- # Box: (X0, Y0, X1, Y1)
- box_coords = (geom[:2], geom[2:])
- else:
- raise ValueError("Only should be 2 or 4 numeric elements.")
- # If a GeoRSS box was given via tuple.
- if box_coords is not None:
- if w3c_geo:
- raise ValueError(
- "Cannot use simple GeoRSS box in W3C Geo feeds."
- )
- handler.addQuickElement(
- "georss:box", self.georss_coords(box_coords)
- )
- else:
- # Getting the lowercase geometry type.
- gtype = str(geom.geom_type).lower()
- if gtype == "point":
- self.add_georss_point(handler, geom.coords, w3c_geo=w3c_geo)
- else:
- if w3c_geo:
- raise ValueError("W3C Geo only supports Point geometries.")
- # For formatting consistent w/the GeoRSS simple standard:
- # http://georss.org/1.0#simple
- if gtype in ("linestring", "linearring"):
- handler.addQuickElement(
- "georss:line", self.georss_coords(geom.coords)
- )
- elif gtype in ("polygon",):
- # Only support the exterior ring.
- handler.addQuickElement(
- "georss:polygon", self.georss_coords(geom[0].coords)
- )
- else:
- raise ValueError(
- 'Geometry type "%s" not supported.' % geom.geom_type
- )
-
-
- # ### SyndicationFeed subclasses ###
- class GeoRSSFeed(Rss201rev2Feed, GeoFeedMixin):
- def rss_attributes(self):
- attrs = super().rss_attributes()
- attrs["xmlns:georss"] = "http://www.georss.org/georss"
- return attrs
-
- def add_item_elements(self, handler, item):
- super().add_item_elements(handler, item)
- self.add_georss_element(handler, item)
-
- def add_root_elements(self, handler):
- super().add_root_elements(handler)
- self.add_georss_element(handler, self.feed)
-
-
- class GeoAtom1Feed(Atom1Feed, GeoFeedMixin):
- def root_attributes(self):
- attrs = super().root_attributes()
- attrs["xmlns:georss"] = "http://www.georss.org/georss"
- return attrs
-
- def add_item_elements(self, handler, item):
- super().add_item_elements(handler, item)
- self.add_georss_element(handler, item)
-
- def add_root_elements(self, handler):
- super().add_root_elements(handler)
- self.add_georss_element(handler, self.feed)
-
-
- class W3CGeoFeed(Rss201rev2Feed, GeoFeedMixin):
- def rss_attributes(self):
- attrs = super().rss_attributes()
- attrs["xmlns:geo"] = "http://www.w3.org/2003/01/geo/wgs84_pos#"
- return attrs
-
- def add_item_elements(self, handler, item):
- super().add_item_elements(handler, item)
- self.add_georss_element(handler, item, w3c_geo=True)
-
- def add_root_elements(self, handler):
- super().add_root_elements(handler)
- self.add_georss_element(handler, self.feed, w3c_geo=True)
-
-
- # ### Feed subclass ###
- class Feed(BaseFeed):
- """
- This is a subclass of the `Feed` from `django.contrib.syndication`.
- This allows users to define a `geometry(obj)` and/or `item_geometry(item)`
- methods on their own subclasses so that geo-referenced information may
- placed in the feed.
- """
-
- feed_type = GeoRSSFeed
-
- def feed_extra_kwargs(self, obj):
- return {"geometry": self._get_dynamic_attr("geometry", obj)}
-
- def item_extra_kwargs(self, item):
- return {"geometry": self._get_dynamic_attr("item_geometry", item)}
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