qgsfieldmappingmodel.h

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/***************************************************************************
  qgsfieldmappingmodel.h - QgsFieldMappingModel
 
 ---------------------
 begin                : 17.3.2020
 copyright            : (C) 2020 by Alessandro Pasotti
 email                : elpaso at itopen dot it
 ***************************************************************************
 *                                                                         *
 *   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 QGSFIELDMAPPINGMODEL_H
#define QGSFIELDMAPPINGMODEL_H
 
#include <QAbstractTableModel>
#include <QStyledItemDelegate>
 
#include "qgsfields.h"
#include "qgsexpressioncontextgenerator.h"
#include "qgsfieldconstraints.h"
#include "qgsproperty.h"
#include "qgis_gui.h"
 
 
class GUI_EXPORT QgsFieldMappingModel: public QAbstractTableModel
{
 
    Q_OBJECT
 
  public:
 
    enum class ColumnDataIndex : int
    {
      SourceExpression,       
      DestinationName,        
      DestinationType,        
      DestinationLength,      
      DestinationPrecision,   
      DestinationConstraints, 
    };
 
    Q_ENUM( ColumnDataIndex );
 
    struct Field
    {
      QString originalName;
      QgsField field;
      QString expression;
    };
 
    QgsFieldMappingModel( const QgsFields &sourceFields = QgsFields(),
                          const QgsFields &destinationFields = QgsFields(),
                          const QMap<QString, QString> &expressions = QMap<QString, QString>(),
                          QObject *parent = nullptr );
 
    bool destinationEditable() const;
 
    void setDestinationEditable( bool editable );
 
    static const QMap<QVariant::Type, QString> dataTypes();
 
    QgsFields sourceFields() const;
 
    QList<QgsFieldMappingModel::Field> mapping() const;
 
    QMap< QString, QgsProperty > fieldPropertyMap() const;
 
    void setFieldPropertyMap( const QMap< QString, QgsProperty > &map );
 
    void appendField( const QgsField &field, const QString &expression = QString() );
 
    bool removeField( const QModelIndex &index );
 
    bool moveUp( const QModelIndex &index );
 
    bool moveDown( const QModelIndex &index );
 
    void setSourceFields( const QgsFields &sourceFields );
 
    QgsExpressionContextGenerator *contextGenerator() const;
 
    void setBaseExpressionContextGenerator( const QgsExpressionContextGenerator *generator );
 
    void setDestinationFields( const QgsFields &destinationFields,
                               const QMap<QString, QString> &expressions = QMap<QString, QString>() );
 
    // QAbstractItemModel interface
    int rowCount( const QModelIndex &parent = QModelIndex() ) const override;
    int columnCount( const QModelIndex &parent = QModelIndex() ) const override;
    QVariant data( const QModelIndex &index, int role ) const override;
    QVariant headerData( int section, Qt::Orientation orientation, int role ) const override;
    Qt::ItemFlags flags( const QModelIndex &index ) const override;
    bool setData( const QModelIndex &index, const QVariant &value, int role ) override;
 
  private:
 
    class ExpressionContextGenerator: public QgsExpressionContextGenerator
    {
 
      public:
 
        ExpressionContextGenerator( const QgsFields &sourceFields );
 
        // QgsExpressionContextGenerator interface
        QgsExpressionContext createExpressionContext() const override;
        void setBaseExpressionContextGenerator( const QgsExpressionContextGenerator *generator );
        void setSourceFields( const QgsFields &fields );
 
      private:
 
        const QgsExpressionContextGenerator *mBaseGenerator = nullptr;
 
        QgsFields mSourceFields;
 
    };
 
 
    QgsFieldConstraints::Constraints fieldConstraints( const QgsField &field ) const;
 
    bool moveUpOrDown( const QModelIndex &index, bool up = true );
 
    QString findExpressionForDestinationField( const QgsFieldMappingModel::Field &field, QStringList &excludedFieldNames );
 
    QList<Field> mMapping;
    bool mDestinationEditable = false;
    QgsFields mSourceFields;
    std::unique_ptr<ExpressionContextGenerator> mExpressionContextGenerator;
 
    friend class QgsAggregateMappingModel;
 
};
 
 
 
#endif // QGSFIELDMAPPINGMODEL_H