--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/datacage/templating/DataFromArtifactXPathFunction.java	Wed Jul 25 14:42:44 2018 +0200
@@ -0,0 +1,56 @@
+/** Copyright (C) 2017 by Bundesanstalt für Gewässerkunde
+ * Software engineering by
+ *  Björnsen Beratende Ingenieure GmbH
+ *  Dr. Schumacher Ingenieurbüro für Wasser und Umwelt
+ *
+ * This file is Free Software under the GNU AGPL (>=v3)
+ * and comes with ABSOLUTELY NO WARRANTY! Check out the
+ * documentation coming with Dive4Elements River for details.
+ */
+package org.dive4elements.river.artifacts.datacage.templating;
+
+import java.util.List;
+import java.util.UUID;
+
+import javax.xml.xpath.XPathFunction;
+import javax.xml.xpath.XPathFunctionException;
+
+import org.dive4elements.artifactdatabase.data.StateData;
+import org.dive4elements.artifacts.CallContext;
+import org.dive4elements.river.artifacts.D4EArtifact;
+import org.dive4elements.river.utils.RiverUtils;
+
+/**
+ * Very specialized function the resolves the 'year' (als middle of all used events) from a fix-analysis-vollmer
+ * artifact).
+ *
+ * @author Gernot Belger
+ */
+public class DataFromArtifactXPathFunction implements XPathFunction {
+
+    public static final String ID = "data_from_artifact";
+
+    public static final int ARITY = 2;
+
+    private final CallContext context;
+
+    public DataFromArtifactXPathFunction(final CallContext context) {
+        this.context = context;
+    }
+
+    @Override
+    public Object evaluate(final List args) throws XPathFunctionException {
+
+        final UUID uuid = (UUID) args.get(0);
+        if (uuid == null)
+            return null;
+
+        final D4EArtifact artifact = RiverUtils.getArtifact(uuid.toString(), this.context);
+        if (!(args.get(1) instanceof String))
+            return null;
+
+        final StateData data = artifact.getData(args.get(1).toString());
+        return data.getValue();
+
+    }
+}
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