[Qgis-user] WFS with filters

[Rahkonen Jukka]

Hi,

What is the situation with the ticket
https://trac.osgeo.org/qgis/ticket/3728 about making filtered
GetFeatures from WFS?

For example with OpenStreetMap WFS layers the plain GetFeature (possibly
with BBOX) does not yield the most usable data for users. By this
request the user gets all kind of polygons like buildings, lakes and
playgrounds.

http://188.64.1.61/cgi-bin/tinyows?service=wfs&version=1.1.0&request=get
feature&typename=tows:osm_polygon&maxfeatures=100

While this one gives just lakes with natural=water filter:

http://188.64.1.61/cgi-bin/tinyows?service=wfs&version=1.1.0&request=get
feature&typename=tows:osm_polygon&maxfeatures=100&filter=%3CFilter%20%20
xmlns:ogc=%22http://www.opengis.net/ogc%22%3E%3CPropertyIsEqualTo%3E%3CP
ropertyName%3Etows:natural%3C/PropertyName%3E%3CLiteral%3Ewater%3C/Liter
al%3E%3C/PropertyIsEqualTo%3E%3C/Filter%3E

Naturally the normal usage is to use http POST but it is easier to show
an example with http GET url.

Of the existing open source GIS programs perhaps the best examples about
how to build WFS filters can be found from iGeoDesktop
(http://www.deegree.org) and Kosmo (http://opengeo.es). Observe that
user can also create spatial filters by using the geometry of a feature
that is selected from the map window.  This enables queries like "select
features having ATTRIBUTE1=xxx AND ATTRIBUTE2=YYY within distance of
20km from the selected feature".  CadCorp SIS MapBrowser is also worth
having a look.

-Jukka Rahkonen-

 

 

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