org.deegree.io.datastore.sql
Class FeatureFetcher

java.lang.Object
  org.deegree.io.datastore.sql.AbstractRequestHandler
      org.deegree.io.datastore.sql.FeatureFetcher

Direct Known Subclasses:

QueryHandler

abstract class FeatureFetcher
extends AbstractRequestHandler

The only implementation of this abstract class is the QueryHandler class.

While the QueryHandler class performs the initial SELECT, FeatureFetcher is responsible for any subsequent SELECTs that may be necessary.

Version:

$Revision: 18195 $, $Date: 2009-06-18 17:55:39 +0200 (Do, 18. Jun 2009) $

Author:

Markus Schneider, last edited by: $Author: mschneider $

See Also:

QueryHandler

Field Summary

protected Map<FeatureId,Feature>	featureMap
protected Set<FeatureId>	featuresInGeneration
protected Map<FeatureId,List<FeatureProperty>>	fidToPropertyMap
protected Query	query
protected VirtualContentProvider	vcProvider

Fields inherited from class org.deegree.io.datastore.sql.AbstractRequestHandler

aliasGenerator, conn, datastore, FT_COLUMN, FT_PREFIX

Constructor Summary

FeatureFetcher(AbstractSQLDatastore datastore, TableAliasGenerator aliasGenerator, Connection conn, Query query)

Method Summary

protected void	appendQualifiedContentList(StatementBuffer query, String tableAlias, List<List<SimpleContent>> fetchContents)
protected Map<SimpleContent,Integer>	buildResultPosMap(List<List<SimpleContent>> fetchContents) Builds a lookup map that allows to find the index (position in the ResultSet) by the SimpleContent instance that makes it necessary to fetch it.
protected List<List<SimpleContent>>	determineFetchContents(MappedFeatureType ft, PropertyType[] requestedProps) Determines the columns / functions that have to be fetched from the table of the given MappedFeatureType and associates identical columns / functions to avoid that the same column / function is SELECTed more than once.
protected Feature	extractFeature(FeatureId fid, Map<MappedPropertyType,Collection<PropertyPath>> requestedPropertyMap, Map<SimpleContent,Integer> resultPosMap, Object[] resultValues) Extracts a feature from the values of a result set row.
protected FeatureId	extractFeatureId(MappedFeatureType ft, Map<SimpleContent,Integer> mfMap, Object[] resultValues) Extracts the feature id from the values of a result set row.

Methods inherited from class org.deegree.io.datastore.sql.AbstractRequestHandler

appendColumnsList, appendFeatureIdColumns, appendFeatureIdConstraint, appendFeatureIdConstraint, appendJoinCondition, appendJoins, appendQualifiedColumn, appendQualifiedColumnsList, determineAffectedAndModifiableFIDs, determineAffectedFIDs, determineSubFeatures, determineSuperFeatures, extractFeatureId, extractFeatureIds, extractFeatureIdsForceUnique

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

featuresInGeneration

protected Set<FeatureId> featuresInGeneration

featureMap

protected Map<FeatureId,Feature> featureMap

fidToPropertyMap

protected Map<FeatureId,List<FeatureProperty>> fidToPropertyMap

vcProvider

protected VirtualContentProvider vcProvider

query

protected Query query

Constructor Detail

FeatureFetcher

FeatureFetcher(AbstractSQLDatastore datastore,
               TableAliasGenerator aliasGenerator,
               Connection conn,
               Query query)
         throws DatastoreException

Throws:

DatastoreException

Method Detail

extractFeature

protected Feature extractFeature(FeatureId fid,
                                 Map<MappedPropertyType,Collection<PropertyPath>> requestedPropertyMap,
                                 Map<SimpleContent,Integer> resultPosMap,
                                 Object[] resultValues)
                          throws SQLException,
                                 DatastoreException,
                                 UnknownCRSException

Extracts a feature from the values of a result set row.

Parameters:

fid - feature id of the feature

requestedPropertyMap - requested MappedPropertyTypes mapped to Collection of PropertyPaths

resultPosMap - key class: MappingField, value class: Integer (this is the associated index in resultValues)

resultValues - all retrieved columns from one result set row

Returns:

the extracted feature

Throws:

SQLException - if a JDBC related error occurs

DatastoreException

UnknownCRSException

extractFeatureId

protected FeatureId extractFeatureId(MappedFeatureType ft,
                                     Map<SimpleContent,Integer> mfMap,
                                     Object[] resultValues)
                              throws DatastoreException

Extracts the feature id from the values of a result set row.

Parameters:

ft - feature type for which the id shall be extracted

mfMap - key class: MappingField, value class: Integer (this is the associated index in resultValues)

resultValues - all retrieved columns from one result set row

Returns:

the feature id

Throws:

DatastoreException

determineFetchContents

protected List<List<SimpleContent>> determineFetchContents(MappedFeatureType ft,
                                                           PropertyType[] requestedProps)
                                                    throws DatastoreException

Determines the columns / functions that have to be fetched from the table of the given MappedFeatureType and associates identical columns / functions to avoid that the same column / function is SELECTed more than once.

Identical columns are put into the same (inner) list.

The following SimpleContent instances of the MappedFeatureTypes annotation are used to build the list:

• MappingFields from the wfs:gmlId - annotation element of the feature type definition
• MappingFields in the annotations of the property element definitions; if the property's content is stored in a related table, the MappingFields used in the first wfs:Relation element's wfs:From element are considered
• SQLFunctionCalls in the annotations of the property element definitions; if the property's (derived) content is stored in a related table, the MappingFields used in the first wfs:Relation element's wfs:From element are considered

Parameters:

ft - feature type for which the content list is built

requestedProps - requested properties

Returns:

List of Lists (that contains SimpleContent instance that refer the same column)

Throws:

DatastoreException

appendQualifiedContentList

protected void appendQualifiedContentList(StatementBuffer query,
                                          String tableAlias,
                                          List<List<SimpleContent>> fetchContents)

buildResultPosMap

protected Map<SimpleContent,Integer> buildResultPosMap(List<List<SimpleContent>> fetchContents)

Builds a lookup map that allows to find the index (position in the ResultSet) by the SimpleContent instance that makes it necessary to fetch it.

Parameters:

fetchContents -

Returns:

key: SimpleContent, value: Integer (position in ResultSet)