I got it working now.
The trick was to extract/evaluate the feature using the join alias as attribute.
It is encrypted in the documentation probably but for experienced geotools
users/developers but without an example it is difficult for simple developers
like me.
This is a working example:
query = new Query("GEO_TABLE");
query.setAlias("a");
Join join = new Join("ADMIN_TABLE",
m_filterFactory.equals(m_filterFactory.property("a.\"ID\""),
m_filterFactory.property("b.\"GEO_ID\"")));
join.setAlias("b");
List<PropertyName> properties = new ArrayList<PropertyName>();
properties.add(m_filterFactory.property("THEME_ATTRIBUTE"));
join.setProperties(properties);
query.getJoins().add(join);
query.setPropertyNames(new String[] {"GEOMETRIE"});
FeatureSource featureSource = m_datastore.getAbsoluteFeatureSource("GEO_TABLE");
SimpleFeatureTypeBuilder typeBuilder = new SimpleFeatureTypeBuilder();
typeBuilder.setName("TEST");
typeBuilder.add("GEOMETRIE", Geometry.class, crs);
SimpleFeatureType simpleFeatureType = typeBuilder.buildFeatureType();
final SimpleFeatureBuilder featureBuilder = new
SimpleFeatureBuilder(simpleFeatureType);
final ListFeatureCollection features = new
ListFeatureCollection(simpleFeatureType);
FeatureCollection featureCollection = featureSource.getFeatures(query);
final Expression geometriepath = m_filterFactory.property("GEOMETRIE");
final Expression joinedfeaturepath = m_filterFactory.property("b");
final Expression attributepath = m_filterFactory.property("THEME_ATTRIBUTE");
featureCollection.accepts( new FeatureVisitor(){
public void visit(Feature feature)
{
Geometry geom = (Geometry) ((SimpleFeature) feature).getDefaultGeometry();
featureBuilder.add(geom);
Feature joinedfeature = joinedfeaturepath.evaluate(feature, Feature.class);
// First extract the joined feature
String attribute = attributepath.evaluate(joinedfeaturepath, String.class);
// Take the attribute of the joined feature
featureBuilder.add(attribute);
features.add(featureBuilder.buildFeature(feature.getIdentifier().getID()));
}
}, null);
layer = new FeatureLayer(features, styleGeometry); // styleGeometry contains
rules for THEME_ATTRIBUTE
On Monday, December 23, 2013 4:10 PM, Andrea Aime
<[email protected]> wrote:
On Mon, Dec 23, 2013 at 2:28 PM, Ron Lindhoudt <[email protected]> wrote:
Hi Andrea,
>
>
>I sent this mail to the geotools user list but I did not see it distributed
>yet.
It has been distributed, see these public archives:
http://osgeo-org.1560.x6.nabble.com/geotools-gt2-users-f4317834.html
It's just that the person that did develop join support is unlikely to answer
because he's in
vacation, and normally does not answer anyways, unless, I guess, you have a
support contract
with Boundless.
I don't know the answer off the top of my head, I'd need to do some research
myself,
but as far as I remember, jonining in GeoTools does not work like in databases,
giving
you a flat representation of the output, but returns tuples, sets of full
features,
with a main feature and some associated features, each one in its own
attribute, see
here:
http://docs.codehaus.org/display/GEOTOOLS/Join+Support
Cheers
Andrea
--
== GeoSolutions will be closed for seasonal holidays from 23/12/2013 to
06/01/2014 ==
Ing. Andrea Aime
@geowolf
Technical Lead
GeoSolutions S.A.S.
Via Poggio alle Viti 1187
55054 Massarosa (LU)
Italy
phone: +39 0584 962313
fax: +39 0584 1660272
mob: +39 339 8844549
http://www.geo-solutions.it
http://twitter.com/geosolutions_it
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