Had this in devel, but perhaps it fits better here:
I am very new to geoserver/geotools and filter functions, however, I have a
couple simple ones that I've put together and am doing some testing on.
They sit behind the geoserver wfs plugin service. As I move beyond the very
simplest examples though I seem to run into some issues. Rather than go
through all of those specifics though, I am wondering, first, if there is
something very basic that I am misunderstanding.
Can someone verify or clarify my following understanding of the
evaluate(Object feature) method (I'm extending FunctionImpl)? My assumption
was that feature parameter represented one record from the datastore and
that this method would be called on each record to return the value
(typically true/false in my case for use with PropertyIsEqualTo) for that
record.
In reality though I'm seeing that the method appears to only be called once
(not once per record in data store) and that the feature parameter is always
null. I've also noticed that the arguments are extracted with code like
this:
double speed = super.getParameters().get(3).evaluate(feature,Double.class);
Which succeeds despite the null value (?) and gets the proper info from my
xml request. This makes me think that maybe the parameter is actually the
wfs request rather than the data store record(s), but the fact that its null
seems odd - and if this is the case then I'm not sure how I can access the
data store/layer data.
I'm sure I've missed something obvious and apologize if this question is a
little too basic, but being pretty new to GIS too, I'm having a hard time
finding these answers. Any help would be greatly appreciated.
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