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qgsvectorlayerjoinbuffer.cpp
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qgsvectorlayerjoinbuffer.cpp
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/***************************************************************************
qgsvectorlayerjoinbuffer.cpp
----------------------------
begin : Feb 09, 2011
copyright : (C) 2011 by Marco Hugentobler
email : marco dot hugentobler at sourcepole dot ch
***************************************************************************/
/***************************************************************************
* *
* 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 "qgsvectorlayerjoinbuffer.h"
#include "qgsfeatureiterator.h"
#include "qgslogger.h"
#include "qgsproject.h"
#include "qgsvectordataprovider.h"
#include <QDomElement>
QgsVectorLayerJoinBuffer::QgsVectorLayerJoinBuffer( QgsVectorLayer *layer )
: mLayer( layer )
{
}
static QList<QgsVectorLayer *> _outEdges( QgsVectorLayer *vl )
{
QList<QgsVectorLayer *> lst;
Q_FOREACH ( const QgsVectorLayerJoinInfo &info, vl->vectorJoins() )
{
if ( QgsVectorLayer *joinVl = info.joinLayer() )
lst << joinVl;
}
return lst;
}
static bool _hasCycleDFS( QgsVectorLayer *n, QHash<QgsVectorLayer *, int> &mark )
{
if ( mark.value( n ) == 1 ) // temporary
return true;
if ( mark.value( n ) == 0 ) // not visited
{
mark[n] = 1; // temporary
Q_FOREACH ( QgsVectorLayer *m, _outEdges( n ) )
{
if ( _hasCycleDFS( m, mark ) )
return true;
}
mark[n] = 2; // permanent
}
return false;
}
bool QgsVectorLayerJoinBuffer::addJoin( const QgsVectorLayerJoinInfo &joinInfo )
{
QMutexLocker locker( &mMutex );
mVectorJoins.push_back( joinInfo );
// run depth-first search to detect cycles in the graph of joins between layers.
// any cycle would cause infinite recursion when updating fields
QHash<QgsVectorLayer *, int> markDFS;
if ( mLayer && _hasCycleDFS( mLayer, markDFS ) )
{
// we have to reject this one
mVectorJoins.pop_back();
return false;
}
//cache joined layer to virtual memory if specified by user
if ( joinInfo.isUsingMemoryCache() )
{
cacheJoinLayer( mVectorJoins.last() );
}
// Wait for notifications about changed fields in joined layer to propagate them.
// During project load the joined layers possibly do not exist yet so the connection will not be created,
// but then QgsProject makes sure to call createJoinCaches() which will do the connection.
// Unique connection makes sure we do not respond to one layer's update more times (in case of multiple join)
if ( QgsVectorLayer *vl = joinInfo.joinLayer() )
{
connectJoinedLayer( vl );
}
emit joinedFieldsChanged();
return true;
}
bool QgsVectorLayerJoinBuffer::removeJoin( const QString &joinLayerId )
{
QMutexLocker locker( &mMutex );
bool res = false;
for ( int i = 0; i < mVectorJoins.size(); ++i )
{
if ( mVectorJoins.at( i ).joinLayerId() == joinLayerId )
{
if ( QgsVectorLayer *vl = mVectorJoins.at( i ).joinLayer() )
{
disconnect( vl, &QgsVectorLayer::updatedFields, this, &QgsVectorLayerJoinBuffer::joinedLayerUpdatedFields );
}
mVectorJoins.removeAt( i );
res = true;
}
}
emit joinedFieldsChanged();
return res;
}
void QgsVectorLayerJoinBuffer::cacheJoinLayer( QgsVectorLayerJoinInfo &joinInfo )
{
//memory cache not required or already done
if ( !joinInfo.isUsingMemoryCache() || !joinInfo.cacheDirty )
{
return;
}
QgsVectorLayer *cacheLayer = joinInfo.joinLayer();
if ( cacheLayer )
{
int joinFieldIndex = cacheLayer->fields().indexFromName( joinInfo.joinFieldName() );
if ( joinFieldIndex < 0 || joinFieldIndex >= cacheLayer->fields().count() )
return;
joinInfo.cachedAttributes.clear();
QgsFeatureRequest request;
request.setFlags( QgsFeatureRequest::NoGeometry );
// maybe user requested just a subset of layer's attributes
// so we do not have to cache everything
bool hasSubset = joinInfo.joinFieldNamesSubset();
QVector<int> subsetIndices;
if ( hasSubset )
{
subsetIndices = joinSubsetIndices( cacheLayer, *joinInfo.joinFieldNamesSubset() );
// we need just subset of attributes - but make sure to include join field name
QgsAttributeList cacheLayerAttrs = subsetIndices.toList();
if ( !cacheLayerAttrs.contains( joinFieldIndex ) )
cacheLayerAttrs.append( joinFieldIndex );
request.setSubsetOfAttributes( cacheLayerAttrs );
}
QgsFeatureIterator fit = cacheLayer->getFeatures( request );
QgsFeature f;
while ( fit.nextFeature( f ) )
{
QgsAttributes attrs = f.attributes();
QString key = attrs.at( joinFieldIndex ).toString();
if ( hasSubset )
{
QgsAttributes subsetAttrs( subsetIndices.count() );
for ( int i = 0; i < subsetIndices.count(); ++i )
subsetAttrs[i] = attrs.at( subsetIndices.at( i ) );
joinInfo.cachedAttributes.insert( key, subsetAttrs );
}
else
{
QgsAttributes attrs2 = attrs;
attrs2.remove( joinFieldIndex ); // skip the join field to avoid double field names (fields often have the same name)
joinInfo.cachedAttributes.insert( key, attrs2 );
}
}
joinInfo.cacheDirty = false;
}
}
QVector<int> QgsVectorLayerJoinBuffer::joinSubsetIndices( QgsVectorLayer *joinLayer, const QStringList &joinFieldsSubset )
{
QVector<int> subsetIndices;
const QgsFields &fields = joinLayer->fields();
for ( int i = 0; i < joinFieldsSubset.count(); ++i )
{
QString joinedFieldName = joinFieldsSubset.at( i );
int index = fields.lookupField( joinedFieldName );
if ( index != -1 )
{
subsetIndices.append( index );
}
else
{
QgsDebugMsg( "Join layer subset field not found: " + joinedFieldName );
}
}
return subsetIndices;
}
void QgsVectorLayerJoinBuffer::updateFields( QgsFields &fields )
{
QString prefix;
QList< QgsVectorLayerJoinInfo>::const_iterator joinIt = mVectorJoins.constBegin();
for ( int joinIdx = 0 ; joinIt != mVectorJoins.constEnd(); ++joinIt, ++joinIdx )
{
QgsVectorLayer *joinLayer = joinIt->joinLayer();
if ( !joinLayer )
{
continue;
}
const QgsFields &joinFields = joinLayer->fields();
QString joinFieldName = joinIt->joinFieldName();
QSet<QString> subset;
bool hasSubset = false;
if ( joinIt->joinFieldNamesSubset() )
{
hasSubset = true;
subset = QSet<QString>::fromList( *joinIt->joinFieldNamesSubset() );
}
if ( joinIt->prefix().isNull() )
{
prefix = joinLayer->name() + '_';
}
else
{
prefix = joinIt->prefix();
}
for ( int idx = 0; idx < joinFields.count(); ++idx )
{
// if using just a subset of fields, filter some of them out
if ( hasSubset && !subset.contains( joinFields.at( idx ).name() ) )
continue;
//skip the join field to avoid double field names (fields often have the same name)
// when using subset of field, use all the selected fields
if ( hasSubset || joinFields.at( idx ).name() != joinFieldName )
{
QgsField f = joinFields.at( idx );
f.setName( prefix + f.name() );
fields.append( f, QgsFields::OriginJoin, idx + ( joinIdx * 1000 ) );
}
}
}
}
void QgsVectorLayerJoinBuffer::createJoinCaches()
{
QMutexLocker locker( &mMutex );
QList< QgsVectorLayerJoinInfo >::iterator joinIt = mVectorJoins.begin();
for ( ; joinIt != mVectorJoins.end(); ++joinIt )
{
if ( joinIt->isUsingMemoryCache() && joinIt->cacheDirty )
cacheJoinLayer( *joinIt );
}
}
void QgsVectorLayerJoinBuffer::writeXml( QDomNode &layer_node, QDomDocument &document ) const
{
QDomElement vectorJoinsElem = document.createElement( QStringLiteral( "vectorjoins" ) );
layer_node.appendChild( vectorJoinsElem );
QList< QgsVectorLayerJoinInfo >::const_iterator joinIt = mVectorJoins.constBegin();
for ( ; joinIt != mVectorJoins.constEnd(); ++joinIt )
{
QDomElement joinElem = document.createElement( QStringLiteral( "join" ) );
joinElem.setAttribute( QStringLiteral( "targetFieldName" ), joinIt->targetFieldName() );
joinElem.setAttribute( QStringLiteral( "joinLayerId" ), joinIt->joinLayerId() );
joinElem.setAttribute( QStringLiteral( "joinFieldName" ), joinIt->joinFieldName() );
joinElem.setAttribute( QStringLiteral( "memoryCache" ), joinIt->isUsingMemoryCache() );
joinElem.setAttribute( QStringLiteral( "dynamicForm" ), joinIt->isDynamicFormEnabled() );
if ( joinIt->joinFieldNamesSubset() )
{
QDomElement subsetElem = document.createElement( QStringLiteral( "joinFieldsSubset" ) );
Q_FOREACH ( const QString &fieldName, *joinIt->joinFieldNamesSubset() )
{
QDomElement fieldElem = document.createElement( QStringLiteral( "field" ) );
fieldElem.setAttribute( QStringLiteral( "name" ), fieldName );
subsetElem.appendChild( fieldElem );
}
joinElem.appendChild( subsetElem );
}
if ( !joinIt->prefix().isNull() )
{
joinElem.setAttribute( QStringLiteral( "customPrefix" ), joinIt->prefix() );
joinElem.setAttribute( QStringLiteral( "hasCustomPrefix" ), 1 );
}
vectorJoinsElem.appendChild( joinElem );
}
}
void QgsVectorLayerJoinBuffer::readXml( const QDomNode &layer_node )
{
mVectorJoins.clear();
QDomElement vectorJoinsElem = layer_node.firstChildElement( QStringLiteral( "vectorjoins" ) );
if ( !vectorJoinsElem.isNull() )
{
QDomNodeList joinList = vectorJoinsElem.elementsByTagName( QStringLiteral( "join" ) );
for ( int i = 0; i < joinList.size(); ++i )
{
QDomElement infoElem = joinList.at( i ).toElement();
QgsVectorLayerJoinInfo info;
info.setJoinFieldName( infoElem.attribute( QStringLiteral( "joinFieldName" ) ) );
// read layer ID - to turn it into layer object, caller will need to call resolveReferences() later
info.setJoinLayerId( infoElem.attribute( QStringLiteral( "joinLayerId" ) ) );
info.setTargetFieldName( infoElem.attribute( QStringLiteral( "targetFieldName" ) ) );
info.setUsingMemoryCache( infoElem.attribute( QStringLiteral( "memoryCache" ) ).toInt() );
info.setDynamicFormEnabled( infoElem.attribute( QStringLiteral( "dynamicForm" ) ).toInt() );
QDomElement subsetElem = infoElem.firstChildElement( QStringLiteral( "joinFieldsSubset" ) );
if ( !subsetElem.isNull() )
{
QStringList *fieldNames = new QStringList;
QDomNodeList fieldNodes = infoElem.elementsByTagName( QStringLiteral( "field" ) );
fieldNames->reserve( fieldNodes.count() );
for ( int i = 0; i < fieldNodes.count(); ++i )
*fieldNames << fieldNodes.at( i ).toElement().attribute( QStringLiteral( "name" ) );
info.setJoinFieldNamesSubset( fieldNames );
}
if ( infoElem.attribute( QStringLiteral( "hasCustomPrefix" ) ).toInt() )
info.setPrefix( infoElem.attribute( QStringLiteral( "customPrefix" ) ) );
else
info.setPrefix( QString() );
addJoin( info );
}
}
}
void QgsVectorLayerJoinBuffer::resolveReferences( QgsProject *project )
{
bool resolved = false;
for ( QgsVectorJoinList::iterator it = mVectorJoins.begin(); it != mVectorJoins.end(); ++it )
{
if ( it->joinLayer() )
continue; // already resolved
if ( QgsVectorLayer *joinedLayer = qobject_cast<QgsVectorLayer *>( project->mapLayer( it->joinLayerId() ) ) )
{
it->setJoinLayer( joinedLayer );
connectJoinedLayer( joinedLayer );
resolved = true;
}
}
if ( resolved )
emit joinedFieldsChanged();
}
int QgsVectorLayerJoinBuffer::joinedFieldsOffset( const QgsVectorLayerJoinInfo *info, const QgsFields &fields )
{
if ( !info )
return -1;
int joinIndex = mVectorJoins.indexOf( *info );
if ( joinIndex == -1 )
return -1;
for ( int i = 0; i < fields.count(); ++i )
{
if ( fields.fieldOrigin( i ) != QgsFields::OriginJoin )
continue;
if ( fields.fieldOriginIndex( i ) / 1000 == joinIndex )
return i;
}
return -1;
}
const QgsVectorLayerJoinInfo *QgsVectorLayerJoinBuffer::joinForFieldIndex( int index, const QgsFields &fields, int &sourceFieldIndex ) const
{
if ( fields.fieldOrigin( index ) != QgsFields::OriginJoin )
return nullptr;
int originIndex = fields.fieldOriginIndex( index );
int sourceJoinIndex = originIndex / 1000;
sourceFieldIndex = originIndex % 1000;
if ( sourceJoinIndex < 0 || sourceJoinIndex >= mVectorJoins.count() )
return nullptr;
return &( mVectorJoins[sourceJoinIndex] );
}
QList<const QgsVectorLayerJoinInfo *> QgsVectorLayerJoinBuffer::joinsWhereFieldIsId( const QgsField &field ) const
{
QList<const QgsVectorLayerJoinInfo *> infos;
Q_FOREACH ( const QgsVectorLayerJoinInfo &info, mVectorJoins )
{
if ( infos.contains( &info ) )
continue;
if ( info.targetFieldName() == field.name() )
infos.append( &info );
}
return infos;
}
QgsFeature QgsVectorLayerJoinBuffer::joinedFeatureOf( const QgsVectorLayerJoinInfo *info, const QgsFeature &feature ) const
{
QgsFeature joinedFeature;
if ( info->joinLayer() )
{
const QVariant targetValue = feature.attribute( info->targetFieldName() );
QString fieldRef = QgsExpression::quotedColumnRef( info->joinFieldName() );
QString quotedVal = QgsExpression::quotedValue( targetValue.toString() );
const QString filter = QStringLiteral( "%1 = %2" ).arg( fieldRef, quotedVal );
QgsFeatureRequest request;
request.setFilterExpression( filter );
request.setLimit( 1 );
QgsFeatureIterator it = info->joinLayer()->getFeatures( request );
it.nextFeature( joinedFeature );
}
return joinedFeature;
}
QgsVectorLayerJoinBuffer *QgsVectorLayerJoinBuffer::clone() const
{
QgsVectorLayerJoinBuffer *cloned = new QgsVectorLayerJoinBuffer( mLayer );
cloned->mVectorJoins = mVectorJoins;
return cloned;
}
void QgsVectorLayerJoinBuffer::joinedLayerUpdatedFields()
{
// TODO - check - this whole method is probably not needed anymore,
// since the cache handling is covered by joinedLayerModified()
QgsVectorLayer *joinedLayer = qobject_cast<QgsVectorLayer *>( sender() );
Q_ASSERT( joinedLayer );
// recache the joined layer
for ( QgsVectorJoinList::iterator it = mVectorJoins.begin(); it != mVectorJoins.end(); ++it )
{
if ( joinedLayer == it->joinLayer() )
{
it->cachedAttributes.clear();
cacheJoinLayer( *it );
}
}
emit joinedFieldsChanged();
}
void QgsVectorLayerJoinBuffer::joinedLayerModified()
{
QgsVectorLayer *joinedLayer = qobject_cast<QgsVectorLayer *>( sender() );
Q_ASSERT( joinedLayer );
// recache the joined layer
for ( QgsVectorJoinList::iterator it = mVectorJoins.begin(); it != mVectorJoins.end(); ++it )
{
if ( joinedLayer == it->joinLayer() )
{
it->cacheDirty = true;
}
}
}
void QgsVectorLayerJoinBuffer::joinedLayerWillBeDeleted()
{
QgsVectorLayer *joinedLayer = qobject_cast<QgsVectorLayer *>( sender() );
Q_ASSERT( joinedLayer );
removeJoin( joinedLayer->id() );
}
void QgsVectorLayerJoinBuffer::connectJoinedLayer( QgsVectorLayer *vl )
{
connect( vl, &QgsVectorLayer::updatedFields, this, &QgsVectorLayerJoinBuffer::joinedLayerUpdatedFields, Qt::UniqueConnection );
connect( vl, &QgsVectorLayer::layerModified, this, &QgsVectorLayerJoinBuffer::joinedLayerModified, Qt::UniqueConnection );
connect( vl, &QgsVectorLayer::willBeDeleted, this, &QgsVectorLayerJoinBuffer::joinedLayerWillBeDeleted, Qt::UniqueConnection );
}