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qgsogrfeatureiterator.cpp
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qgsogrfeatureiterator.cpp
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/***************************************************************************
qgsogrfeatureiterator.cpp
---------------------
begin : Juli 2012
copyright : (C) 2012 by Martin Dobias
email : wonder dot sk at gmail dot com
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************/
#include "qgsogrfeatureiterator.h"
#include "qgsogrprovider.h"
#include "qgsogrexpressioncompiler.h"
#include "qgssqliteexpressioncompiler.h"
#include "qgsogrutils.h"
#include "qgsapplication.h"
#include "qgsgeometry.h"
#include "qgslogger.h"
#include "qgsmessagelog.h"
#include "qgssettings.h"
#include "qgsexception.h"
#include "qgswkbtypes.h"
#include <QTextCodec>
#include <QFile>
// using from provider:
// - setRelevantFields(), mRelevantFieldsForNextFeature
// - ogrLayer
// - mFetchFeaturesWithoutGeom
// - mAttributeFields
// - mEncoding
QgsOgrFeatureIterator::QgsOgrFeatureIterator( QgsOgrFeatureSource *source, bool ownSource, const QgsFeatureRequest &request )
: QgsAbstractFeatureIteratorFromSource<QgsOgrFeatureSource>( source, ownSource, request )
, mFilterFids( mRequest.filterFids() )
, mFilterFidsIt( mFilterFids.constBegin() )
{
//QgsDebugMsg( "Feature iterator of " + mSource->mLayerName + ": acquiring connection");
mConn = QgsOgrConnPool::instance()->acquireConnection( QgsOgrProviderUtils::connectionPoolId( mSource->mDataSource ) );
if ( !mConn->ds )
{
return;
}
if ( mSource->mLayerName.isNull() )
{
mOgrLayer = GDALDatasetGetLayer( mConn->ds, mSource->mLayerIndex );
}
else
{
mOgrLayer = GDALDatasetGetLayerByName( mConn->ds, mSource->mLayerName.toUtf8().constData() );
}
if ( !mOgrLayer )
{
return;
}
if ( !mSource->mSubsetString.isEmpty() )
{
mOgrOrigLayer = mOgrLayer;
mOgrLayer = QgsOgrProviderUtils::setSubsetString( mOgrOrigLayer, mConn->ds, mSource->mEncoding, mSource->mSubsetString, mOrigFidAdded );
if ( !mOgrLayer )
{
close();
return;
}
}
if ( mRequest.destinationCrs().isValid() && mRequest.destinationCrs() != mSource->mCrs )
{
mTransform = QgsCoordinateTransform( mSource->mCrs, mRequest.destinationCrs(), mRequest.transformContext() );
}
try
{
mFilterRect = filterRectToSourceCrs( mTransform );
}
catch ( QgsCsException & )
{
// can't reproject mFilterRect
close();
return;
}
mFetchGeometry = ( !mFilterRect.isNull() ) ||
!( mRequest.flags() & QgsFeatureRequest::NoGeometry ) ||
( mSource->mOgrGeometryTypeFilter != wkbUnknown );
QgsAttributeList attrs = ( mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes ) ? mRequest.subsetOfAttributes() : mSource->mFields.allAttributesList();
// ensure that all attributes required for expression filter are being fetched
if ( mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes && request.filterType() == QgsFeatureRequest::FilterExpression )
{
//ensure that all fields required for filter expressions are prepared
QSet<int> attributeIndexes = request.filterExpression()->referencedAttributeIndexes( mSource->mFields );
attributeIndexes += attrs.toSet();
attrs = attributeIndexes.toList();
mRequest.setSubsetOfAttributes( attrs );
}
// also need attributes required by order by
if ( mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes && !mRequest.orderBy().isEmpty() )
{
QSet<int> attributeIndexes;
Q_FOREACH ( const QString &attr, mRequest.orderBy().usedAttributes() )
{
attributeIndexes << mSource->mFields.lookupField( attr );
}
attributeIndexes += attrs.toSet();
attrs = attributeIndexes.toList();
mRequest.setSubsetOfAttributes( attrs );
}
if ( request.filterType() == QgsFeatureRequest::FilterExpression && request.filterExpression()->needsGeometry() )
{
mFetchGeometry = true;
}
// make sure we fetch just relevant fields
// unless it's a VRT data source filtered by geometry as we don't know which
// attributes make up the geometry and OGR won't fetch them to evaluate the
// filter if we choose to ignore them (fixes #11223)
if ( ( mSource->mDriverName != QLatin1String( "VRT" ) && mSource->mDriverName != QLatin1String( "OGR_VRT" ) ) || mFilterRect.isNull() )
{
QgsOgrProviderUtils::setRelevantFields( mOgrLayer, mSource->mFields.count(), mFetchGeometry, attrs, mSource->mFirstFieldIsFid );
}
// spatial query to select features
if ( !mFilterRect.isNull() )
{
OGR_L_SetSpatialFilterRect( mOgrLayer, mFilterRect.xMinimum(), mFilterRect.yMinimum(), mFilterRect.xMaximum(), mFilterRect.yMaximum() );
}
else
{
OGR_L_SetSpatialFilter( mOgrLayer, nullptr );
}
if ( request.filterType() == QgsFeatureRequest::FilterExpression
&& QgsSettings().value( QStringLiteral( "qgis/compileExpressions" ), true ).toBool() )
{
QgsSqlExpressionCompiler *compiler = nullptr;
if ( source->mDriverName == QLatin1String( "SQLite" ) || source->mDriverName == QLatin1String( "GPKG" ) )
{
compiler = new QgsSQLiteExpressionCompiler( source->mFields );
}
else
{
compiler = new QgsOgrExpressionCompiler( source );
}
QgsSqlExpressionCompiler::Result result = compiler->compile( request.filterExpression() );
if ( result == QgsSqlExpressionCompiler::Complete || result == QgsSqlExpressionCompiler::Partial )
{
QString whereClause = compiler->result();
if ( OGR_L_SetAttributeFilter( mOgrLayer, mSource->mEncoding->fromUnicode( whereClause ).constData() ) == OGRERR_NONE )
{
//if only partial success when compiling expression, we need to double-check results using QGIS' expressions
mExpressionCompiled = ( result == QgsSqlExpressionCompiler::Complete );
mCompileStatus = ( mExpressionCompiled ? Compiled : PartiallyCompiled );
}
}
else
{
OGR_L_SetAttributeFilter( mOgrLayer, nullptr );
}
delete compiler;
}
else
{
OGR_L_SetAttributeFilter( mOgrLayer, nullptr );
}
//start with first feature
rewind();
}
QgsOgrFeatureIterator::~QgsOgrFeatureIterator()
{
close();
}
bool QgsOgrFeatureIterator::nextFeatureFilterExpression( QgsFeature &f )
{
if ( !mExpressionCompiled )
return QgsAbstractFeatureIterator::nextFeatureFilterExpression( f );
else
return fetchFeature( f );
}
bool QgsOgrFeatureIterator::fetchFeatureWithId( QgsFeatureId id, QgsFeature &feature ) const
{
feature.setValid( false );
gdal::ogr_feature_unique_ptr fet;
if ( mOrigFidAdded )
{
// if we have been using the original fid as feature IDs (e.g. as a result of a subset
// string in place), then we need to request features from the original, unfiltered
// OGR layer. Otherwise the feature IDs we request will correspond to features in the
// filtered layer, not the original layer!
OGR_L_ResetReading( mOgrOrigLayer );
fet.reset( OGR_L_GetFeature( mOgrOrigLayer, FID_TO_NUMBER( id ) ) );
// do a bit of a safety check - make sure that the original fid column value
// matches the feature id which we actually requested.
OGRFeatureDefnH fdef = OGR_L_GetLayerDefn( mOgrOrigLayer );
int lastField = OGR_FD_GetFieldCount( fdef ) - 1;
bool foundCorrect = false;
if ( lastField >= 0 )
foundCorrect = OGR_F_GetFieldAsInteger64( fet.get(), lastField ) == id;
else
foundCorrect = OGR_F_GetFID( fet.get() ) == id;
if ( !foundCorrect )
{
fet.reset();
}
}
else
{
fet.reset( OGR_L_GetFeature( mOgrLayer, FID_TO_NUMBER( id ) ) );
}
if ( !fet )
{
return false;
}
readFeature( std::move( fet ), feature );
feature.setValid( true );
geometryToDestinationCrs( feature, mTransform );
return true;
}
bool QgsOgrFeatureIterator::fetchFeature( QgsFeature &feature )
{
feature.setValid( false );
if ( mClosed || !mOgrLayer )
return false;
if ( mRequest.filterType() == QgsFeatureRequest::FilterFid )
{
bool result = fetchFeatureWithId( mRequest.filterFid(), feature );
close(); // the feature has been read or was not found: we have finished here
return result;
}
else if ( mRequest.filterType() == QgsFeatureRequest::FilterFids )
{
while ( mFilterFidsIt != mFilterFids.constEnd() )
{
QgsFeatureId nextId = *mFilterFidsIt;
mFilterFidsIt++;
if ( fetchFeatureWithId( nextId, feature ) )
return true;
}
close();
return false;
}
gdal::ogr_feature_unique_ptr fet;
while ( fet.reset( OGR_L_GetNextFeature( mOgrLayer ) ), fet )
{
if ( !readFeature( std::move( fet ), feature ) )
continue;
if ( !mFilterRect.isNull() && ( !feature.hasGeometry() || feature.geometry().isEmpty() ) )
continue;
// we have a feature, end this cycle
feature.setValid( true );
geometryToDestinationCrs( feature, mTransform );
return true;
} // while
close();
return false;
}
bool QgsOgrFeatureIterator::rewind()
{
if ( mClosed || !mOgrLayer )
return false;
OGR_L_ResetReading( mOgrLayer );
mFilterFidsIt = mFilterFids.constBegin();
return true;
}
bool QgsOgrFeatureIterator::close()
{
if ( !mConn )
return false;
iteratorClosed();
// Will for example release SQLite3 statements
if ( mOgrLayer )
{
OGR_L_ResetReading( mOgrLayer );
}
if ( mOgrOrigLayer )
{
GDALDatasetReleaseResultSet( mConn->ds, mOgrLayer );
mOgrLayer = mOgrOrigLayer;
mOgrOrigLayer = nullptr;
}
if ( mConn )
{
//QgsDebugMsg( "Feature iterator of " + mSource->mLayerName + ": releasing connection");
QgsOgrConnPool::instance()->releaseConnection( mConn );
}
mConn = nullptr;
mOgrLayer = nullptr;
mClosed = true;
return true;
}
void QgsOgrFeatureIterator::getFeatureAttribute( OGRFeatureH ogrFet, QgsFeature &f, int attindex ) const
{
if ( mSource->mFirstFieldIsFid && attindex == 0 )
{
f.setAttribute( 0, static_cast<qint64>( OGR_F_GetFID( ogrFet ) ) );
return;
}
int attindexWithoutFid = ( mSource->mFirstFieldIsFid ) ? attindex - 1 : attindex;
bool ok = false;
QVariant value = QgsOgrUtils::getOgrFeatureAttribute( ogrFet, mSource->mFieldsWithoutFid, attindexWithoutFid, mSource->mEncoding, &ok );
if ( !ok )
return;
f.setAttribute( attindex, value );
}
bool QgsOgrFeatureIterator::readFeature( gdal::ogr_feature_unique_ptr fet, QgsFeature &feature ) const
{
if ( mOrigFidAdded )
{
OGRFeatureDefnH fdef = OGR_L_GetLayerDefn( mOgrLayer );
int lastField = OGR_FD_GetFieldCount( fdef ) - 1;
if ( lastField >= 0 )
feature.setId( OGR_F_GetFieldAsInteger64( fet.get(), lastField ) );
else
feature.setId( OGR_F_GetFID( fet.get() ) );
}
else
{
feature.setId( OGR_F_GetFID( fet.get() ) );
}
feature.initAttributes( mSource->mFields.count() );
feature.setFields( mSource->mFields ); // allow name-based attribute lookups
bool useIntersect = !mRequest.filterRect().isNull() && mRequest.flags() & QgsFeatureRequest::ExactIntersect;
bool geometryTypeFilter = mSource->mOgrGeometryTypeFilter != wkbUnknown;
if ( mFetchGeometry || useIntersect || geometryTypeFilter )
{
OGRGeometryH geom = OGR_F_GetGeometryRef( fet.get() );
if ( geom )
{
QgsGeometry g = QgsOgrUtils::ogrGeometryToQgsGeometry( geom );
// Insure that multipart datasets return multipart geometry
if ( QgsWkbTypes::isMultiType( mSource->mWkbType ) && !g.isMultipart() )
{
g.convertToMultiType();
}
feature.setGeometry( g );
}
else
feature.clearGeometry();
if ( mSource->mOgrGeometryTypeFilter == wkbGeometryCollection &&
geom && wkbFlatten( OGR_G_GetGeometryType( geom ) ) == wkbGeometryCollection )
{
// OK
}
else if ( ( useIntersect && ( !feature.hasGeometry() || !feature.geometry().intersects( mFilterRect ) ) )
|| ( geometryTypeFilter && ( !feature.hasGeometry() || QgsOgrProvider::ogrWkbSingleFlatten( ( OGRwkbGeometryType )feature.geometry().wkbType() ) != mSource->mOgrGeometryTypeFilter ) ) )
{
return false;
}
}
if ( !mFetchGeometry )
{
feature.clearGeometry();
}
// fetch attributes
if ( mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes )
{
QgsAttributeList attrs = mRequest.subsetOfAttributes();
for ( QgsAttributeList::const_iterator it = attrs.constBegin(); it != attrs.constEnd(); ++it )
{
getFeatureAttribute( fet.get(), feature, *it );
}
}
else
{
// all attributes
for ( int idx = 0; idx < mSource->mFields.count(); ++idx )
{
getFeatureAttribute( fet.get(), feature, idx );
}
}
return true;
}
QgsOgrFeatureSource::QgsOgrFeatureSource( const QgsOgrProvider *p )
: mDataSource( p->dataSourceUri( true ) )
, mLayerName( p->layerName() )
, mLayerIndex( p->layerIndex() )
, mSubsetString( p->mSubsetString )
, mEncoding( p->textEncoding() ) // no copying - this is a borrowed pointer from Qt
, mFields( p->mAttributeFields )
, mFirstFieldIsFid( p->mFirstFieldIsFid )
, mOgrGeometryTypeFilter( QgsOgrProvider::ogrWkbSingleFlatten( p->mOgrGeometryTypeFilter ) )
, mDriverName( p->mGDALDriverName )
, mCrs( p->crs() )
, mWkbType( p->wkbType() )
{
for ( int i = ( p->mFirstFieldIsFid ) ? 1 : 0; i < mFields.size(); i++ )
mFieldsWithoutFid.append( mFields.at( i ) );
QgsOgrConnPool::instance()->ref( QgsOgrProviderUtils::connectionPoolId( mDataSource ) );
}
QgsOgrFeatureSource::~QgsOgrFeatureSource()
{
QgsOgrConnPool::instance()->unref( QgsOgrProviderUtils::connectionPoolId( mDataSource ) );
}
QgsFeatureIterator QgsOgrFeatureSource::getFeatures( const QgsFeatureRequest &request )
{
return QgsFeatureIterator( new QgsOgrFeatureIterator( this, false, request ) );
}