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qgsrelationreferencefieldformatter.cpp
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qgsrelationreferencefieldformatter.cpp
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/***************************************************************************
qgsrelationreferencefieldformatter.cpp - QgsRelationReferenceFieldFormatter
---------------------
begin : 3.12.2016
copyright : (C) 2016 by Matthias Kuhn
email : matthias@opengis.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 "qgsrelationreferencefieldformatter.h"
#include "qgsmessagelog.h"
#include "qgsrelation.h"
#include "qgsexpressioncontext.h"
#include "qgsproject.h"
#include "qgsrelationmanager.h"
#include "qgsvectorlayer.h"
#include "qgsexpressioncontextutils.h"
QString QgsRelationReferenceFieldFormatter::id() const
{
return QStringLiteral( "RelationReference" );
}
QString QgsRelationReferenceFieldFormatter::representValue( QgsVectorLayer *layer, int fieldIndex, const QVariantMap &config, const QVariant &cache, const QVariant &value ) const
{
if ( cache.isValid() )
{
return cache.value<QMap<QVariant, QString>>().value( value );
}
const QString fieldName = fieldIndex < layer->fields().size() ? layer->fields().at( fieldIndex ).name() : QObject::tr( "<unknown>" );
// Some sanity checks
if ( !config.contains( QStringLiteral( "Relation" ) ) )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: Missing Relation in configuration" ).arg( layer->name(), fieldName ) );
return value.toString();
}
const QString relationName = config[QStringLiteral( "Relation" )].toString();
QgsRelation relation = QgsProject::instance()->relationManager()->relation( relationName );
if ( !relation.isValid() )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: Invalid relation %3" ).arg( layer->name(), fieldName, relationName ) );
return value.toString();
}
QgsVectorLayer *referencingLayer = relation.referencingLayer();
if ( layer != referencingLayer )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: representValue() with inconsistent layer parameter w.r.t relation referencingLayer" ).arg( layer->name(), fieldName ) );
return value.toString();
}
int referencingFieldIdx = referencingLayer->fields().lookupField( relation.fieldPairs().at( 0 ).first );
if ( referencingFieldIdx != fieldIndex )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: representValue() with inconsistent fieldIndex parameter w.r.t relation referencingFieldIdx" ).arg( layer->name(), fieldName ) );
return value.toString();
}
QgsVectorLayer *referencedLayer = relation.referencedLayer();
if ( !referencedLayer )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: Cannot find referenced layer" ).arg( layer->name(), fieldName ) );
return value.toString();
}
// Attributes from the referencing layer
QgsAttributes attrs = QgsAttributes( layer->fields().count() );
// Set the value on the foreign key field of the referencing record
attrs[ referencingFieldIdx ] = value;
QgsFeatureRequest request = relation.getReferencedFeatureRequest( attrs );
QgsFeature feature;
referencedLayer->getFeatures( request ).nextFeature( feature );
if ( !feature.isValid() )
return value.toString();
QgsExpression expr( referencedLayer->displayExpression() );
QgsExpressionContext context( QgsExpressionContextUtils::globalProjectLayerScopes( referencedLayer ) );
context.setFeature( feature );
QString title = expr.evaluate( &context ).toString();
if ( expr.hasEvalError() )
{
int referencedFieldIdx = referencedLayer->fields().lookupField( relation.fieldPairs().at( 0 ).second );
title = feature.attribute( referencedFieldIdx ).toString();
}
return title;
}
QVariant QgsRelationReferenceFieldFormatter::sortValue( QgsVectorLayer *layer, int fieldIndex, const QVariantMap &config, const QVariant &cache, const QVariant &value ) const
{
return representValue( layer, fieldIndex, config, cache, value );
}
QVariant QgsRelationReferenceFieldFormatter::createCache( QgsVectorLayer *layer, int fieldIndex, const QVariantMap &config ) const
{
Q_UNUSED( fieldIndex )
QMap<QVariant, QString> cache;
const QString fieldName = fieldIndex < layer->fields().size() ? layer->fields().at( fieldIndex ).name() : QObject::tr( "<unknown>" );
// Some sanity checks
if ( !config.contains( QStringLiteral( "Relation" ) ) )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: Missing Relation in configuration" ).arg( layer->name(), fieldName ) );
return QVariant();
}
const QString relationName = config[QStringLiteral( "Relation" )].toString();
QgsRelation relation = QgsProject::instance()->relationManager()->relation( config[QStringLiteral( "Relation" )].toString() );
if ( !relation.isValid() )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: Invalid relation %3" ).arg( layer->name(), fieldName, relationName ) );
return QVariant();
}
QgsVectorLayer *referencingLayer = relation.referencingLayer();
if ( layer != referencingLayer )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: representValue() with inconsistent layer parameter w.r.t relation referencingLayer" ).arg( layer->name(), fieldName ) );
return QVariant();
}
QgsVectorLayer *referencedLayer = relation.referencedLayer();
if ( !referencedLayer )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: Cannot find referenced layer" ).arg( layer->name(), fieldName ) );
return QVariant();
}
int referencedFieldIdx = referencedLayer->fields().lookupField( relation.fieldPairs().at( 0 ).second );
if ( referencedFieldIdx == -1 )
{
QgsMessageLog::logMessage( QObject::tr( "Layer %1, field %2: Invalid referenced field (%3) configured in relation %4" ).arg( layer->name(), fieldName, relation.fieldPairs().at( 0 ).second, relation.name() ) );
return QVariant();
}
QgsExpression expr( referencedLayer->displayExpression() );
QgsFeatureRequest request;
request.setFlags( QgsFeatureRequest::NoGeometry );
QgsAttributeList requiredAttributes = expr.referencedAttributeIndexes( referencedLayer->fields() ).toList();
requiredAttributes << referencedFieldIdx;
request.setSubsetOfAttributes( requiredAttributes );
QgsFeature feature;
auto iterator = referencedLayer->getFeatures( request );
QgsExpressionContext context( QgsExpressionContextUtils::globalProjectLayerScopes( referencedLayer ) );
expr.prepare( &context );
while ( iterator.nextFeature( feature ) )
{
context.setFeature( feature );
QString title = expr.evaluate( &context ).toString();
if ( expr.hasEvalError() )
{
int referencedFieldIdx = referencedLayer->fields().lookupField( relation.fieldPairs().at( 0 ).second );
title = feature.attribute( referencedFieldIdx ).toString();
}
cache.insert( feature.attribute( referencedFieldIdx ), title );
}
return QVariant::fromValue<QMap<QVariant, QString>>( cache );
}