qgsrelation.h

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/***************************************************************************
    qgsrelation.h
     --------------------------------------
    Date                 : 29.4.2013
    Copyright            : (C) 2013 Matthias Kuhn
    Email                : matthias at opengis 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.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef QGSRELATION_H
#define QGSRELATION_H

#include <QList>
#include <QDomNode>
#include <QPair>

#include "qgis_core.h"
#include "qgsfields.h"

#include "qgis.h"

class QgsVectorLayer;
class QgsFeatureIterator;
class QgsFeature;
class QgsFeatureRequest;
class QgsAttributes;

class CORE_EXPORT QgsRelation
{
    Q_GADGET

    Q_PROPERTY( QString id READ id WRITE setId )
    Q_PROPERTY( QgsVectorLayer *referencingLayer READ referencingLayer )
    Q_PROPERTY( QgsVectorLayer *referencedLayer READ referencedLayer )
    Q_PROPERTY( QString name READ name WRITE setName )
    Q_PROPERTY( bool isValid READ isValid )


  public:

    enum RelationStrength
    {
      Association, 
      Composition  

    };

#ifndef SIP_RUN

    class FieldPair : public QPair< QString, QString >
    {
      public:
        FieldPair() = default;

        FieldPair( const QString &referencingField, const QString &referencedField )
          : QPair< QString, QString >( referencingField, referencedField ) {}

        QString referencingField() const { return first; }
        QString referencedField() const { return second; }

        bool operator==( const FieldPair &other ) const { return first == other.first && second == other.second; }
    };
#endif

    QgsRelation() = default;

    static QgsRelation createFromXml( const QDomNode &node );

    void writeXml( QDomNode &node, QDomDocument &doc ) const;

    void setId( const QString &id );

    void setName( const QString &name );

    void setStrength( RelationStrength strength );

    void setReferencingLayer( const QString &id );

    void setReferencedLayer( const QString &id );

    void addFieldPair( const QString &referencingField, const QString &referencedField );

    void addFieldPair( const FieldPair &fieldPair ) SIP_SKIP;

    QgsFeatureIterator getRelatedFeatures( const QgsFeature &feature ) const;

    QgsFeatureRequest getRelatedFeaturesRequest( const QgsFeature &feature ) const;

    QString getRelatedFeaturesFilter( const QgsFeature &feature ) const;

    QgsFeatureRequest getReferencedFeatureRequest( const QgsAttributes &attributes ) const;

    QgsFeatureRequest getReferencedFeatureRequest( const QgsFeature &feature ) const;

    QgsFeature getReferencedFeature( const QgsFeature &feature ) const;

    QString name() const;

    RelationStrength strength() const;

    QString id() const;

    void generateId();

    QString referencingLayerId() const;

    QgsVectorLayer *referencingLayer() const;

    QString referencedLayerId() const;

    QgsVectorLayer *referencedLayer() const;

#ifndef SIP_RUN
    QList< QgsRelation::FieldPair > fieldPairs() const;
#else
    QMap< QString, QString > fieldPairs() const;
    % MethodCode
    const QList< QgsRelation::FieldPair > &pairs = sipCpp->fieldPairs();
    sipRes = new QMap< QString, QString >();
    for ( const QgsRelation::FieldPair &pair : pairs )
    {
      sipRes->insert( pair.first, pair.second );
    }
    % End
#endif

    QgsAttributeList referencedFields() const;

    QgsAttributeList referencingFields() const;

    bool isValid() const;

    bool hasEqualDefinition( const QgsRelation &other ) const;

    Q_INVOKABLE QString resolveReferencedField( const QString &referencingField ) const;

    Q_INVOKABLE QString resolveReferencingField( const QString &referencedField ) const;

  private:

    void updateRelationStatus();

    QString mRelationId;
    QString mRelationName;
    QString mReferencingLayerId;
    QgsVectorLayer *mReferencingLayer = nullptr;
    QString mReferencedLayerId;
    QgsVectorLayer *mReferencedLayer = nullptr;

    RelationStrength mRelationStrength = Association;

    QList< FieldPair > mFieldPairs;

    bool mValid = false;
};

// Register QgsRelation for usage with QVariant
Q_DECLARE_METATYPE( QgsRelation )
Q_DECLARE_METATYPE( QgsRelation::RelationStrength )

#endif // QGSRELATION_H