/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.data;
import org.geotools.factory.Hints;
import org.opengis.feature.Feature;
import org.opengis.filter.sort.SortBy;
/**
* Describes the query capabilities for a specific FeatureType, so client code can request which
* features are natively supported by a FeatureSource.
* <p>
* This is the minimal Query capabilities we could come up in order to reliably support paging. Yet,
* the need for a more complete set of capabilities is well known and a new proposal should be done
* in order to define the complete set of capabilities a FeatureSource should advertise.
* </p>
*
* @author Gabriel Roldan (TOPP)
* @version $Id$
* @since 2.5.x
*
* @source $URL$
*/
public class QueryCapabilities {
/**
* Returns the list of filters natively supported by the underlaying storage. Every other filter
* will be emulated in memory (and thus will not enjoy any acceleration).
*/
// GR: commenting out by now as its being an unexpected scope increase,
// gonna add it back once I have the paging use case handled
// FilterCapabilities getFilterCapabilities();
/**
* True if this feature source supports reprojection
*/
// public boolean isReprojectionSupported();
/**
*
*/
// public boolean isCRSForcingSupported();
/**
* Is offset supported. A value of true implies ability to have a consistent sort order. At
* least {@link SortBy#NATURAL_ORDER} shall be supported, and be the default order if a Query
* with offset but no SortBy is issued.
*/
public boolean isOffsetSupported() {
return false;
}
/**
* Returns whether a list of properties can be used as SortBy keys.
* <p>
* May include current feature type properties as well as <code>"@id"</code> for sorting on
* the Feature ID. Note, however, that ability to sort by the fature id does not necessarily
* implies the same ordering than SortBy.NATURAL_ORDER, though its probable they match for
* datastores where the feature id is built up from a primary key.
* </p>
* <p>
* Returns true if passed a null or empty array, otherwise the actual attributes are checked.
* When the array is not null and not empty, by default returns false.
* FeatureSource implementations should override as needed.
* </p>
*
* @return whether the FeatureType this query capabilities refers to can be natively sorted by
* the provided list of attribtue/order pairs
*/
public boolean supportsSorting(SortBy[] sortAttributes) {
return (sortAttributes == null) || (sortAttributes.length == 0);
}
/**
* Returns whether the feature source is capable of producing "reliable" fids.
* <p>
* In this content the term "reliable" refers to the ability to read the same feature
* twice (with no transactions against the feature source in the interim) and get the
* same feature id back both times.
* </p>
* @return True to indicate reliable fids are supported, otherwise false.
*/
public boolean isReliableFIDSupported() {
return true;
}
/**
* If true the datastore supports using the provided feature id in the data insertion
* workflow as opposed to generating a new id. In that case it will look into the user data
* map ({@link Feature#getUserData()}) for a {@link Hints#USE_PROVIDED_FID} key associated to a
* {@link Boolean#TRUE} value, if the key/value pair is there an attempt to use the provided
* id will be made, and the operation will fail of the key cannot be parsed into a valid
* storage identifier.
* @return
*/
public boolean isUseProvidedFIDSupported() {
return false;
}
}