QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator( QgsVectorLayerFeatureSource* source, bool ownSource, const QgsFeatureRequest& request )
: QgsAbstractFeatureIteratorFromSource<QgsVectorLayerFeatureSource>( source, ownSource, request )
, mFetchedFid( false )
, mInterruptionChecker( nullptr )
{
if ( mRequest.filterType() == QgsFeatureRequest::FilterExpression )
{
mRequest.expressionContext()->setFields( mSource->mFields );
mRequest.filterExpression()->prepare( mRequest.expressionContext() );
if ( mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes )
{
//ensure that all fields required for filter expressions are prepared
QSet<int> attributeIndexes = mRequest.filterExpression()->referencedAttributeIndexes( mSource->mFields );
attributeIndexes += mRequest.subsetOfAttributes().toSet();
mRequest.setSubsetOfAttributes( attributeIndexes.toList() );
}
}
prepareFields();
mHasVirtualAttributes = !mFetchJoinInfo.isEmpty() || !mExpressionFieldInfo.isEmpty();
// by default provider's request is the same
mProviderRequest = mRequest;
if ( mProviderRequest.flags() & QgsFeatureRequest::SubsetOfAttributes )
{
// prepare list of attributes to match provider fields
QSet<int> providerSubset;
QgsAttributeList subset = mProviderRequest.subsetOfAttributes();
int nPendingFields = mSource->mFields.count();
Q_FOREACH ( int attrIndex, subset )
{
if ( attrIndex < 0 || attrIndex >= nPendingFields )
continue;
if ( mSource->mFields.fieldOrigin( attrIndex ) == QgsFields::OriginProvider )
providerSubset << mSource->mFields.fieldOriginIndex( attrIndex );
}
// This is done in order to be prepared to do fallback order bys
// and be sure we have the required columns.
// TODO:
// It would be nicer to first check if we can compile the order by
// and only modify the subset if we cannot.
if ( !mProviderRequest.orderBy().isEmpty() )
{
Q_FOREACH ( const QString& attr, mProviderRequest.orderBy().usedAttributes() )
{
providerSubset << mSource->mFields.lookupField( attr );
}
}
QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator( QgsVectorLayerFeatureSource *source, bool ownSource, const QgsFeatureRequest &request )
: QgsAbstractFeatureIteratorFromSource<QgsVectorLayerFeatureSource>( source, ownSource, request )
, mFetchedFid( false )
{
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;
}
if ( !mFilterRect.isNull() )
{
// update request to be the unprojected filter rect
mRequest.setFilterRect( mFilterRect );
}
if ( mRequest.filterType() == QgsFeatureRequest::FilterExpression )
{
mRequest.expressionContext()->setFields( mSource->mFields );
mRequest.filterExpression()->prepare( mRequest.expressionContext() );
if ( mRequest.flags() & QgsFeatureRequest::SubsetOfAttributes )
{
//ensure that all fields required for filter expressions are prepared
QSet<int> attributeIndexes = mRequest.filterExpression()->referencedAttributeIndexes( mSource->mFields );
attributeIndexes += mRequest.subsetOfAttributes().toSet();
mRequest.setSubsetOfAttributes( attributeIndexes.toList() );
}
}
prepareFields();
mHasVirtualAttributes = !mFetchJoinInfo.isEmpty() || !mExpressionFieldInfo.isEmpty();
// by default provider's request is the same
mProviderRequest = mRequest;
// but we remove any destination CRS parameter - that is handled in QgsVectorLayerFeatureIterator,
// not at the provider level. Otherwise virtual fields depending on geometry would have incorrect
// values
if ( mRequest.destinationCrs().isValid() )
{
mProviderRequest.setDestinationCrs( QgsCoordinateReferenceSystem(), mRequest.transformContext() );
}
if ( mProviderRequest.flags() & QgsFeatureRequest::SubsetOfAttributes )
{
// prepare list of attributes to match provider fields
QSet<int> providerSubset;
QgsAttributeList subset = mProviderRequest.subsetOfAttributes();
int nPendingFields = mSource->mFields.count();
Q_FOREACH ( int attrIndex, subset )
{
if ( attrIndex < 0 || attrIndex >= nPendingFields )
continue;
if ( mSource->mFields.fieldOrigin( attrIndex ) == QgsFields::OriginProvider )
providerSubset << mSource->mFields.fieldOriginIndex( attrIndex );
}
// This is done in order to be prepared to do fallback order bys
// and be sure we have the required columns.
// TODO:
// It would be nicer to first check if we can compile the order by
// and only modify the subset if we cannot.
if ( !mProviderRequest.orderBy().isEmpty() )
{
Q_FOREACH ( const QString &attr, mProviderRequest.orderBy().usedAttributes() )
{
providerSubset << mSource->mFields.lookupField( attr );
}
}
