/* (c) 2014 Open Source Geospatial Foundation - all rights reserved
* (c) 2014 OpenPlans
* This code is licensed under the GPL 2.0 license, available at the root
* application directory.
*/
package org.geoserver.wps.gs;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;
import org.geoserver.catalog.AttributeTypeInfo;
import org.geotools.data.Query;
import org.geotools.data.simple.SimpleFeatureCollection;
import org.geotools.factory.CommonFactoryFinder;
import org.geotools.feature.visitor.UniqueVisitor;
import org.geotools.filter.text.cql2.CQLException;
import org.geotools.process.ProcessException;
import org.geotools.process.factory.DescribeParameter;
import org.geotools.process.factory.DescribeProcess;
import org.geotools.process.factory.DescribeResult;
import org.geotools.util.logging.Logging;
import org.json.simple.JSONObject;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.filter.Filter;
import org.opengis.filter.FilterFactory;
import org.opengis.filter.sort.SortBy;
import org.opengis.filter.sort.SortOrder;
/**
* A WPS process to retrieve unique field values from a layer on Geoserver
* catalog. Requires a valid layer name and a field name to extract the unique
* values. It accepts sorting and paging parameters.
*
* @author Cesar Martinez Izquierdo
* @author Sandro Salari
* @author Mauro Bartolomeoli
*/
@DescribeProcess(title = "PagedUnique", description = "Gets the list of unique values for the given featurecollection on a specified field, allows optional paging")
public class PagedUniqueProcess implements GeoServerProcess {
/** The LOGGER. */
private static final Logger LOGGER = Logging
.getLogger(PagedUniqueProcess.class);
private final FilterFactory FF = CommonFactoryFinder.getFilterFactory2();
public static final class Results {
private String featureTypeName;
private String fieldName;
private int size;
private List<?> values;
public Results(String featureTypeName, String fieldName, int size,
List<?> values) {
super();
this.featureTypeName = featureTypeName;
this.fieldName = fieldName;
this.size = size;
this.values = values;
}
public String getFeatureTypeName() {
return featureTypeName;
}
public String getFieldName() {
return fieldName;
}
public int getSize() {
return size;
}
public List<?> getValues() {
return values;
}
}
@DescribeResult(name = "result", type = Results.class, description = "List of values")
public Results execute(
@DescribeParameter(name = "features", min = 1, max = 1, description = "Layer from which field values should be retrieved") SimpleFeatureCollection features,
@DescribeParameter(name = "fieldName", min = 1, max = 1, description = "Field from which the values should be retrieved") String fieldName,
@DescribeParameter(name = "startIndex", min = 0, max = 1, description = "The index of the first feature to retrieve") Integer startIndex,
@DescribeParameter(name = "maxFeatures", min = 0, max = 1, description = "The maximum numbers of features to fetch") Integer maxFeatures
)
throws IOException, CQLException {
// initial checks on params
if (features == null) {
throw new IllegalArgumentException("features param cannot be null");
}
if (fieldName == null || fieldName.isEmpty()) {
throw new IllegalArgumentException("Empty or null fieldName provided!");
}
SimpleFeatureType featureType = features.getSchema();
String featureTypeName = featureType.getTypeName();
LOGGER.fine("PagedUnique process called on resource: " + featureTypeName
+ " - field: " + fieldName);
UniqueVisitor visitor = new UniqueVisitor(FF.property(fieldName));
Integer listSize = 0;
List<String> list = new ArrayList<String>();
try {
// counts total elements
features.accepts(visitor, null);
if(visitor.getResult() == null || visitor.getResult().toList() == null) {
listSize = 0;
list = new ArrayList<String>(0);
} else {
listSize = visitor.getResult().toList().size();
if(maxFeatures == null || maxFeatures > listSize) {
maxFeatures = listSize;
}
// Reset visitor and set pagination
visitor.reset();
if(startIndex != null) {
visitor.setStartIndex(startIndex);
}
if(maxFeatures != null) {
visitor.setMaxFeatures(maxFeatures);
}
visitor.setPreserveOrder(true);
features.accepts(visitor, null);
if(visitor.getResult() == null || visitor.getResult().toList() == null) {
list = new ArrayList<String>(0);
} else {
list = visitor.getResult().toList();
}
}
return new Results(featureTypeName, fieldName, listSize, list);
} catch (Exception e) {
throw new ProcessException("Error extracting unique values", e);
}
}
}