Re: [Geotools-devel] Binding DirectPosition with app-schema

[Andrea A. <and...@ge...>]

On Mon, Oct 4, 2010 at 7:26 PM, Andrea Aime
<and...@ge...> wrote:
> Hi,
> I'm trying to use app-schema with a target schema that, unfortunately,
> uses a DirectPosition as
> the feature "geometry". I don't have any control over the schema so I
> have to try and make it work
> anyways.
>
> What I get overall is that my points are turned into their WKT
> representation when the
> GML encoding happens. Which is not what I want.
>
> Looking a bit more deeply I see that the attribute is correctly bound
> to DirectPosition:
> ComplexTypeImpl http://www.opengis.net/gml:DirectPositionType extends
> doubleList(axisLabels:NCNameList,srsDimension:positiveInteger,srsName:anyURI,uomLabels:NCNameList)
> but nowhere in the code there is an attempt to use converters to turn
> the JTS Point into a DirectPosition.
>
> Now, I tracked down the issue to XPath.convertValue:
>
> private Object convertValue(final AttributeDescriptor descriptor,
> final Object value) {
>        final AttributeType type = descriptor.getType();
>        Class<?> binding = type.getBinding();
>
>        if (type instanceof ComplexType && binding == Collection.class) {
>            if (!(value instanceof Collection) && isSimpleContentType(type)) {
>                ArrayList<Property> list = new ArrayList<Property>();
>                if (value == null && !descriptor.isNillable()) {
>                    return list;
>                }
>                list.add(buildSimpleContent(type, value));
>                return list;
>            }
>        }
>        if (binding == String.class && value instanceof Collection) {
>            // if it's a single value in a collection, strip the square brackets
>            String collectionString = value.toString();
>            return collectionString.substring(1, collectionString.length() - 1);
>        }
>        return FF.literal(value).evaluate(value, binding);
>    }
>
> type is a complex type, but binding for some reason is exactly Collection.class,
> which results in the wrong code path being chosen (the right one, imho, would
> be the usage of the last line, FF.literal(value).evaluate(value, binding), which
> could be expressed also as Converters.convert(value, binding)).
>
> Now... does anybody know why the binding ends up being a collection instead
> of org.opengis.geometry.DirectPosition?
> I still haven't quite tracked down where the bindings are built...

Ok, tracked it down.
The GMLSchema class contains the definitions of many gml foundation types,
for point the definition is:


public static final AttributeType POINTTYPE_TYPE = build_POINTTYPE_TYPE();

    private static AttributeType build_POINTTYPE_TYPE() {
        AttributeType builtType;
        builtType = new AttributeTypeImpl(
            new NameImpl("http://www.opengis.net/gml","PointType"),
com.vividsolutions.jts.geom.Point.class, false,
            false, Collections.<Filter>emptyList(),
ABSTRACTGEOMETRICPRIMITIVETYPE_TYPE, null
        );
        return builtType;
    }

Notice the direct binding to Point.class.
But for DirectPosition it is:

public static final ComplexType DIRECTPOSITIONTYPE_TYPE =
build_DIRECTPOSITIONTYPE_TYPE();

    private static ComplexType build_DIRECTPOSITIONTYPE_TYPE() {
        ComplexType builtType;
        List<PropertyDescriptor> schema = new ArrayList<PropertyDescriptor>();
        schema.add(
            new AttributeDescriptorImpl(
                NCNAMELIST_TYPE, new
NameImpl("http://www.opengis.net/gml","axisLabels"), 0, 1, true, null
            )
        );
        schema.add(
            new AttributeDescriptorImpl(
                XSSchema.POSITIVEINTEGER_TYPE, new
NameImpl("http://www.opengis.net/gml","srsDimension"), 0, 1, true,
null
            )
        );
        schema.add(
            new AttributeDescriptorImpl(
                XSSchema.ANYURI_TYPE, new
NameImpl("http://www.opengis.net/gml","srsName"), 0, 1, true, null
            )
        );
        schema.add(
            new AttributeDescriptorImpl(
                NCNAMELIST_TYPE, new
NameImpl("http://www.opengis.net/gml","uomLabels"), 0, 1, true, null
            )
        );
        builtType = new ComplexTypeImpl(
            new
NameImpl("http://www.opengis.net/gml","DirectPositionType"), schema,
false,
            false, Collections.<Filter>emptyList(), DOUBLELIST_TYPE, null
        );
        return builtType;
    }

That is, it's built as a complex type, and all complex types bind to
Collection.class (that's inside the
ComplexTypeImpl constructor).

The change I'm tempted to perform is to make the direct position bound
to a opengis DirectPosition
instead. It would contain the ordinates and the crs, but not the other
attributes...
And then make a converter between Point and DirectPosition... the
DirectPositionTypeBinding
 is actually already there and should work

Thoughts?

Cheers
Andrea


-----------------------------------------------------
Ing. Andrea Aime
Senior Software Engineer

GeoSolutions S.A.S.
Via Poggio alle Viti 1187
55054  Massarosa (LU)
Italy

phone: +39 0584962313
fax:     +39 0584962313

http://www.geo-solutions.it
http://geo-solutions.blogspot.com/
http://www.linkedin.com/in/andreaaime
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