How 2 Map: October 2011

Monday, 31 October 2011

Brisbane Meetup of Aust-NZ OSGeo Chapter

In a fit of ill-advised post FOSS4G enthusiasm I set up a meetup page. In my defence it sounded like a lot of the fun to be had in open source spatial is happening at the OSGeo chapter level.
I was actually concerned that I was taking on too much; that whole feeling of throwing a party and wondering if anyone is going to show...
Turns out we had quite a crowd; and an excellent location looking over the Brisbane river:

Rather than try and provide a summary the first Brisbane "Hack and Yak" here are the links brought up on the big screen:

If any of that looks like fun you are welcome to join us on Friday Nov 11th. I will be on hand with a preview of an upcoming GeoTools Workshop. I also hope to start round 1 of uDig vs QGIS challenge (to try and encourage some creativity).

Friday, 28 October 2011

FeatureId

Small improvement coming out of some recent work on ResourceId.
BEFORE

    Set selected = new HashSet();
    selected.add(ff.featureId("CITY.98734597823459687235"));
    selected.add(ff.featureId("CITY.98734592345235823474"));
    
    filter = ff.id(selected);

AFTER:

    filter = ff.id(ff.featureId("CITY.98734597823459687235"),
                   ff.featureId("CITY.98734592345235823474"));

Documentation harmed in the making of this post:

filter identifier (GeoTools User Guide)
upgrade (GeoTools User Guide)

Tuesday, 18 October 2011

Nothing to see here

A couple new abilities for the GeoTools filter system.
WFS2 includes two ways to check if an attribute does not have a value.

PropertyIsNull can be used to check that a property exists; and that the value is empty.
PropertyIsNil is used to check if a property exists at all

A quick example makes this difference easier to see:
// test if "approval" equals "null"
filter = ff.isNull(ff.property("approved"));
// this example checks if approved exists at all
filter = ff.isNil(ff.property("approved"),"no approval available");

I also found that I had missed documenting how FeatureId can be used to look up a feature by name; or at least identifier.

The example makes use of a Set of FeatureId to construct the appropriate Filter:

Set selected = new HashSet();
selected.add(ff.featureId("CITY.98734597823459687235"));
selected.add(ff.featureId("CITY.98734592345235823474"));
filter = ff.id(selected);

Documentation harmed in the making of this post:

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