qgsvectordataprovider.h

Go to the documentation of this file.

/***************************************************************************
    qgsvectordataprovider.h - DataProvider Interface for vector layers
     --------------------------------------
    Date                 : 23-Sep-2004
    Copyright            : (C) 2004 by Marco Hugentobler
    email                : [email protected]
 ***************************************************************************
 *                                                                         *
 *   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 QGSVECTORDATAPROVIDER_H
#define QGSVECTORDATAPROVIDER_H

class QTextCodec;

#include "qgis_core.h"
#include <QList>
#include <QSet>
#include <QMap>
#include <QHash>

//QGIS Includes
#include "qgis.h"
#include "qgsdataprovider.h"
#include "qgsfeature.h"
#include "qgsaggregatecalculator.h"
#include "qgsmaplayerdependency.h"
#include "qgsrelation.h"
#include "qgsfeaturesink.h"
#include "qgsfeaturesource.h"

typedef QList<int> QgsAttributeList SIP_SKIP;
typedef QSet<int> QgsAttributeIds SIP_SKIP;
typedef QHash<int, QString> QgsAttrPalIndexNameHash;

class QgsFeatureIterator;
class QgsTransaction;
class QgsFeedback;
class QgsFeatureRenderer;

#include "qgsfeaturerequest.h"

class CORE_EXPORT QgsVectorDataProvider : public QgsDataProvider, public QgsFeatureSink, public QgsFeatureSource
{
    Q_OBJECT

    friend class QgsTransaction;
    friend class QgsVectorLayerEditBuffer;

  public:

    // If you add to this, please also add to capabilitiesString()

    enum Capability
    {
      NoCapabilities = 0,       
      AddFeatures = 1,       
      DeleteFeatures = 1 <<  1, 
      ChangeAttributeValues = 1 <<  2, 
      AddAttributes = 1 <<  3, 
      DeleteAttributes = 1 <<  4, 
      CreateSpatialIndex = 1 <<  6, 
      SelectAtId = 1 <<  7, 
      ChangeGeometries = 1 <<  8, 
      SelectEncoding = 1 << 13, 
      CreateAttributeIndex = 1 << 12, 
      SimplifyGeometries = 1 << 14, 
      SimplifyGeometriesWithTopologicalValidation = 1 << 15, 
      TransactionSupport = 1 << 16, 
      CircularGeometries = 1 << 17, 
      ChangeFeatures = 1 << 18, 
      RenameAttributes = 1 << 19, 
      FastTruncate = 1 << 20, 
      ReadLayerMetadata = 1 << 21, 
      WriteLayerMetadata = 1 << 22, 
      CancelSupport = 1 << 23, 
      CreateRenderer = 1 << 24, 
    };

    Q_DECLARE_FLAGS( Capabilities, Capability )

    
    static const int EditingCapabilities = AddFeatures | DeleteFeatures |
                                           ChangeAttributeValues | ChangeGeometries | AddAttributes | DeleteAttributes |
                                           RenameAttributes;

    enum FeatureCountState
    {
      Uncounted = -2,
      UnknownCount = -1,
    };

    QgsVectorDataProvider( const QString &uri = QString(), const QgsDataProvider::ProviderOptions &options = QgsDataProvider::ProviderOptions() );

    virtual QgsAbstractFeatureSource *featureSource() const = 0 SIP_FACTORY;

    virtual QString storageType() const;

    QgsFeatureIterator getFeatures( const QgsFeatureRequest &request = QgsFeatureRequest() ) const override = 0;

    QgsWkbTypes::Type wkbType() const override = 0;

    long featureCount() const override = 0;

    virtual bool empty() const;

    QgsFeatureSource::FeatureAvailability hasFeatures() const override;

    QgsFields fields() const override = 0;

    QgsCoordinateReferenceSystem sourceCrs() const override;
    QgsRectangle sourceExtent() const override;
    QString sourceName() const override { return QString(); }

    virtual QString dataComment() const;

    QVariant minimumValue( int index ) const override;

    QVariant maximumValue( int index ) const override;

    virtual QStringList uniqueStringsMatching( int index, const QString &substring, int limit = -1,
        QgsFeedback *feedback = nullptr ) const;

    virtual QVariant aggregate( QgsAggregateCalculator::Aggregate aggregate,
                                int index,
                                const QgsAggregateCalculator::AggregateParameters &parameters,
                                QgsExpressionContext *context,
                                bool &ok ) const;

    virtual void enumValues( int index, QStringList &enumList SIP_OUT ) const { Q_UNUSED( index ); enumList.clear(); }

    bool addFeatures( QgsFeatureList &flist SIP_INOUT, QgsFeatureSink::Flags flags = nullptr ) override;

    virtual bool deleteFeatures( const QgsFeatureIds &id );

    virtual bool truncate();

    virtual bool cancelReload();

    virtual bool addAttributes( const QList<QgsField> &attributes );

    virtual bool deleteAttributes( const QgsAttributeIds &attributes );

    virtual bool renameAttributes( const QgsFieldNameMap &renamedAttributes );

    virtual bool changeAttributeValues( const QgsChangedAttributesMap &attr_map );

    virtual bool changeFeatures( const QgsChangedAttributesMap &attr_map,
                                 const QgsGeometryMap &geometry_map );

    virtual QVariant defaultValue( int fieldIndex ) const;

    virtual QString defaultValueClause( int fieldIndex ) const;

    QgsFieldConstraints::Constraints fieldConstraints( int fieldIndex ) const;

    virtual bool skipConstraintCheck( int fieldIndex, QgsFieldConstraints::Constraint constraint, const QVariant &value = QVariant() ) const;

    virtual bool changeGeometryValues( const QgsGeometryMap &geometry_map );

    virtual bool createSpatialIndex();

    virtual bool createAttributeIndex( int field );

    virtual QgsVectorDataProvider::Capabilities capabilities() const;

    QString capabilitiesString() const;

    virtual void setEncoding( const QString &e );

    QString encoding() const;

    int fieldNameIndex( const QString &fieldName ) const;

    QMap<QString, int> fieldNameMap() const;

    virtual QgsAttributeList attributeIndexes() const;

    virtual QgsAttributeList pkAttributeIndexes() const;

    virtual QgsAttrPalIndexNameHash palAttributeIndexNames() const;

    bool supportedType( const QgsField &field ) const;

    struct NativeType
    {
      NativeType( const QString &typeDesc, const QString &typeName, QVariant::Type type, int minLen = 0, int maxLen = 0, int minPrec = 0, int maxPrec = 0, QVariant::Type subType = QVariant::Invalid )
        : mTypeDesc( typeDesc )
        , mTypeName( typeName )
        , mType( type )
        , mMinLen( minLen )
        , mMaxLen( maxLen )
        , mMinPrec( minPrec )
        , mMaxPrec( maxPrec )
        , mSubType( subType )
      {}

      QString mTypeDesc;
      QString mTypeName;
      QVariant::Type mType;
      int mMinLen;
      int mMaxLen;
      int mMinPrec;
      int mMaxPrec;
      QVariant::Type mSubType;
    };

    QList< QgsVectorDataProvider::NativeType > nativeTypes() const;

    virtual bool doesStrictFeatureTypeCheck() const { return true; }

    static QStringList availableEncodings();

    bool hasErrors() const;

    void clearErrors();

    QStringList errors() const;

    virtual bool isSaveAndLoadStyleToDatabaseSupported() const;

    virtual bool isDeleteStyleFromDatabaseSupported() const;

    virtual QgsFeatureRenderer *createRenderer( const QVariantMap &configuration = QVariantMap() ) const SIP_FACTORY;

    static QVariant convertValue( QVariant::Type type, const QString &value );

    virtual QgsTransaction *transaction() const;

    virtual void forceReload();

    virtual QSet<QgsMapLayerDependency> dependencies() const;

    virtual QList<QgsRelation> discoverRelations( const QgsVectorLayer *self, const QList<QgsVectorLayer *> &layers ) const;

    virtual QVariantMap metadata() const { return QVariantMap(); }

    virtual QString translateMetadataKey( const QString &mdKey ) const { return mdKey; }

    virtual QString translateMetadataValue( const QString &mdKey, const QVariant &value ) const { Q_UNUSED( mdKey ); return value.toString(); }

    virtual bool hasMetadata() const { return true; }

  signals:

    void raiseError( const QString &msg ) const;

  protected:

    void clearMinMaxCache();

    void fillMinMaxCache() const;

    void pushError( const QString &msg ) const;

    QgsGeometry convertToProviderType( const QgsGeometry &geom ) const;

    void setNativeTypes( const QList<QgsVectorDataProvider::NativeType> &nativeTypes );

    QTextCodec *textEncoding() const;

  private:
    mutable bool mCacheMinMaxDirty = true;
    mutable QMap<int, QVariant> mCacheMinValues, mCacheMaxValues;

    QTextCodec *mEncoding = nullptr;

    QgsAttributeList mAttributesToFetch;

    QList< NativeType > mNativeTypes;

    mutable QStringList mErrors;

    static QStringList sEncodings;

    virtual void setTransaction( QgsTransaction * /*transaction*/ ) {}

};

Q_DECLARE_OPERATORS_FOR_FLAGS( QgsVectorDataProvider::Capabilities )

#endif