I needed marmotta-loader-kiwi to support geometry imports for postgres on
MARMOTTA-584, so I coded up a solution - however, I apologize for not
having the time right now to make clean commits/PRs for this.
Here's some jumpstart info in case someone wants to get this feature on the
timeline:
KiWiPostgresHandler uses "COPY [...] FROM STDIN (FORMAT csv)" to bulk load
triples into postgres. So, the "gvalue" column of an insert node needs to
be in a format that PostGIS understands[1]; which happens to be a strict
EWKT (strict because it does not allow spaces after geometry type, e.g.,
"POINT(" is acceptable but "POINT (" will throw an error.)
The other challenge is setting the CRS/SRID with the serialized geometry
value - somewhere along the import process, the loader needs to replace
GeoSPARQL's CRS format with its corresponding SRID code, e.g. replacing "<
http://www.opengis.net/def/crs/OGC/1.3/CRS84>" with "SRID=4326;" at the
beginning of the WKT string. I think this should be discussed on how to
support various CRS IRI => SRID mappings.
The rest of implementation is pretty straightforward. I'm including below
the diffs of my hacked-together code. Hope this helps!
*commons/marmotta-sesame-tools/marmotta-model-vocabs/src/main/java/org/apache/marmotta/commons/vocabulary/GEOSPARQL.java
*
+package org.apache.marmotta.commons.vocabulary;
+
+import org.openrdf.model.URI;
+import org.openrdf.model.ValueFactory;
+import org.openrdf.model.impl.ValueFactoryImpl;
+
+/**
+ * Created by blake on 8/26/16.
+ */
+public class GEOSPARQL {
+ public static final String NAMESPACE = "
http://www.opengis.net/ont/geosparql#";;
+ public static final String PREFIX = "geosparql";
+
+ /**
+ * The Well-Known-Text IRI of geometry literals
+ */
+ public static final URI wktLiteral;
+
+ static {
+ ValueFactory factory = ValueFactoryImpl.getInstance();
+ wktLiteral = factory.createURI(GEOSPARQL.NAMESPACE, "wktLiteral");
+ }
+}
*libraries/kiwi/kiwi-loader/src/main/java/org/apache/marmotta/kiwi/loader/generic/KiWiHandler.java*
+import org.apache.marmotta.commons.vocabulary.GEOSPARQL;
*...*
+ } else if(type.equals(GEOSPARQL.wktLiteral)) {
+ result = connection.loadLiteral(sanitizeString(value),
rtype);
+
+ if(result == null) {
+ result = new
KiWiGeometryLiteral(sanitizeString(value), rtype, importDate);
+ }
+ else {
+ nodesLoaded++;
+ }
*libraries/kiwi/kiwi-loader/src/main/java/org/apache/marmotta/kiwi/loader/pgsql/PGCopyUtil.java
*
- log.warn("geometries are not yet supported on bulk
imports");
+ KiWiGeometryLiteral l = (KiWiGeometryLiteral)n;
+ createNodeList(rowArray, l.getId(), l.getClass(),
l.getContent(), null, null, null, null, null, l.getDatatype(),
l.getLocale(), l.getCreated(), l.getContent());
*...*
+ // schema v5
if (a.length == 12) {
- a[11] = geom; //schema v5
+ if(geom == null) {
+ a[11] = null;
+ }
+ else {
+ a[11] = geom
+
.replaceFirst("^<http://www\\.opengis\\.net/def/crs/OGC/1\\.3/CRS84>\\s*",
"SRID=4326;") // convert CRS => SRID
+ .replaceFirst("\\s+(", "("); // PostGIS does not
allow spaces after WKT geometry type
+ }
}
[1] - http://stackoverflow.com/a/11137004/1641160
- Blake
