class QgsVectorDataProvider : QgsDataProvider { %TypeHeaderCode #include %End public: // If you add to this, please also add to capabilitiesString() /** * enumeration with capabilities that providers might implement */ enum Capability { /** Provider has no capabilities */ NoCapabilities, /** Allows adding features */ AddFeatures, /** Allows deletion of features */ DeleteFeatures, /** Allows modification of attribute values */ ChangeAttributeValues, /** Allows addition of new attributes (fields) */ AddAttributes, /** Allows deletion of attributes (fields) */ DeleteAttributes, /** Allows creation of spatial index */ CreateSpatialIndex, /** Fast access to features using their ID */ SelectAtId, /** Allows modifications of geometries */ ChangeGeometries, /** DEPRECATED - do not use */ CreateAttributeIndex, /** Allows user to select encoding */ SelectEncoding, /** Supports simplification of geometries on provider side according to a distance tolerance */ SimplifyGeometries, /** Supports topological simplification of geometries on provider side according to a distance tolerance */ SimplifyGeometriesWithTopologicalValidation, /** Supports transactions*/ TransactionSupport, /** Supports circular geometry types (circularstring, compoundcurve, curvepolygon)*/ CircularGeometries, /** Supports joint updates for attributes and geometry * Providers supporting this should still define ChangeGeometries | ChangeAttributeValues */ ChangeFeatures, /** Supports renaming attributes (fields). Added in QGIS 2.16 */ RenameAttributes, }; typedef QFlags Capabilities; /** Bitmask of all provider's editing capabilities */ static const int EditingCapabilities; /** * Constructor of the vector provider * @param uri uniform resource locator (URI) for a dataset */ QgsVectorDataProvider( const QString& uri = QString() ); /** * Destructor */ virtual ~QgsVectorDataProvider(); /** * Return feature source object that can be used for querying provider's data. The returned feature source * is independent from provider - any changes to provider's state (e.g. change of subset string) will not be * reflected in the feature source, therefore it can be safely used for processing in background without * having to care about possible changes within provider that may happen concurrently. Also, even in the case * of provider being deleted, any feature source obtained from the provider will be kept alive and working * (they are independent and owned by the caller). * * Sometimes there are cases when some data needs to be shared between vector data provider and its feature source. * In such cases, the implementation must ensure that the data is not susceptible to run condition. For example, * if it is possible that both feature source and provider may need reading/writing to some shared data at the * same time, some synchronization mechanisms must be used (e.g. mutexes) to prevent data corruption. * * @note added in 2.4 * @return new instance of QgsAbstractFeatureSource (caller is responsible for deleting it) */ virtual QgsAbstractFeatureSource *featureSource() const = 0 /Factory/; /** * Returns the permanent storage type for this layer as a friendly name. */ virtual QString storageType() const; /** * Query the provider for features specified in request. * @param request feature request describing parameters of features to return * @returns iterator for matching features from provider */ virtual QgsFeatureIterator getFeatures( const QgsFeatureRequest& request = QgsFeatureRequest() ) const = 0; /** * Returns the geometry type which is returned by this layer */ virtual QgsWkbTypes::Type wkbType() const = 0; /** * Number of features in the layer * @return long containing number of features */ virtual long featureCount() const = 0; /** * Returns the fields associated with this data provider. */ virtual QgsFields fields() const = 0; /** * Return a short comment for the data that this provider is * providing access to (e.g. the comment for postgres table). */ virtual QString dataComment() const; /** * Returns the minimum value of an attribute * @param index the index of the attribute * * Default implementation walks all numeric attributes and caches minimal * and maximal values. If provider has facilities to retrieve minimal * value directly, override this function. */ virtual QVariant minimumValue( int index ) const; /** * Returns the maximum value of an attribute * @param index the index of the attribute * * Default implementation walks all numeric attributes and caches minimal * and maximal values. If provider has facilities to retrieve maximal * value directly, override this function. */ virtual QVariant maximumValue( int index ) const; /** * Return unique values of an attribute * @param index the index of the attribute * @param uniqueValues values reference to the list to fill * @param limit maxmum number of the values to return * * Default implementation simply iterates the features */ virtual void uniqueValues( int index, QList &uniqueValues /Out/, int limit = -1 ) const; /** Calculates an aggregated value from the layer's features. The base implementation does nothing, * but subclasses can override this method to handoff calculation of aggregates to the provider. * @param aggregate aggregate to calculate * @param index the index of the attribute to calculate aggregate over * @param parameters parameters controlling aggregate calculation * @param context expression context for filter * @param ok will be set to true if calculation was successfully performed by the data provider * @return calculated aggregate value * @note added in QGIS 2.16 */ virtual QVariant aggregate( QgsAggregateCalculator::Aggregate aggregate, int index, const QgsAggregateCalculator::AggregateParameters& parameters, QgsExpressionContext* context, bool& ok ) const; /** * Returns the possible enum values of an attribute. Returns an empty stringlist if a provider does not support enum types * or if the given attribute is not an enum type. * @param index the index of the attribute * @param enumList reference to the list to fill */ virtual void enumValues( int index, QStringList& enumList /Out/ ) const; /** * Adds a list of features * @return true in case of success and false in case of failure */ virtual bool addFeatures( QList &flist /In,Out/ ); /** * Deletes one or more features * @param id list containing feature ids to delete * @return true in case of success and false in case of failure */ virtual bool deleteFeatures( const QSet &id ); /** * Adds new attributes * @param attributes list of new attributes * @return true in case of success and false in case of failure */ virtual bool addAttributes( const QList &attributes ); /** * Deletes existing attributes * @param attributes a set containing indices of attributes * @return true in case of success and false in case of failure */ virtual bool deleteAttributes( const QSet &attributes ); /** * Renames existing attributes. * @param renamedAttributes map of attribute index to new attribute name * @return true in case of success and false in case of failure * @note added in QGIS 2.16 */ virtual bool renameAttributes( const QgsFieldNameMap& renamedAttributes ); /** * Changes attribute values of existing features. * @param attr_map a map containing changed attributes * @return true in case of success and false in case of failure */ virtual bool changeAttributeValues( const QMap > &attr_map ); /** * Changes attribute values and geometries of existing features. * @param attr_map a map containing changed attributes * @param geometry_map A QgsGeometryMap whose index contains the feature IDs * that will have their geometries changed. * The second map parameter being the new geometries themselves * @return true in case of success and false in case of failure */ virtual bool changeFeatures( const QMap > &attr_map, const QMap &geometry_map ); /** * Returns the default value for field specified by @c fieldId */ virtual QVariant defaultValue( int fieldId ) const; /** * Changes geometries of existing features * @param geometry_map A QgsGeometryMap whose index contains the feature IDs * that will have their geometries changed. * The second map parameter being the new geometries themselves * @return True in case of success and false in case of failure */ virtual bool changeGeometryValues( const QMap &geometry_map ); /** * Creates a spatial index on the datasource (if supported by the provider type). * @return true in case of success */ virtual bool createSpatialIndex(); /** Create an attribute index on the datasource*/ virtual bool createAttributeIndex( int field ); /** Returns a bitmask containing the supported capabilities @note, some capabilities may change depending on whether a spatial filter is active on this provider, so it may be prudent to check this value per intended operation. */ virtual Capabilities capabilities() const; /** * Returns the above in friendly format. */ QString capabilitiesString() const; /** * Set encoding used for accessing data from layer */ virtual void setEncoding( const QString& e ); /** * Get encoding which is used for accessing data */ QString encoding() const; /** * Returns the index of a field name or -1 if the field does not exist */ int fieldNameIndex( const QString& fieldName ) const; /** * Return a map where the key is the name of the field and the value is its index */ QMap fieldNameMap() const; /** * Return list of indexes to fetch all attributes in nextFeature() */ virtual QList attributeIndexes() const; /** * Return list of indexes of fields that make up the primary key */ virtual QList pkAttributeIndexes() const; /** * Return list of indexes to names for QgsPalLabeling fix */ virtual QHash palAttributeIndexNames() const; /** * check if provider supports type of field */ 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 ); QString mTypeDesc; QString mTypeName; QVariant::Type mType; int mMinLen; int mMaxLen; int mMinPrec; int mMaxPrec; }; /** * Returns the names of the supported types */ const QList< QgsVectorDataProvider::NativeType > &nativeTypes() const; /** * Returns true if the provider is strict about the type of inserted features * (e.g. no multipolygon in a polygon layer) */ virtual bool doesStrictFeatureTypeCheck() const; /** Returns a list of available encodings */ static QStringList availableEncodings(); /** * Provider has errors to report */ bool hasErrors() const; /** * Clear recorded errors */ void clearErrors(); /** * Get recorded errors */ QStringList errors() const; /** * It returns false by default. * Must be implemented by providers that support saving and loading styles to db returning true */ virtual bool isSaveAndLoadStyleToDBSupported() const; static QVariant convertValue( QVariant::Type type, const QString& value ); /** * Returns the transaction this data provider is included in, if any. */ virtual QgsTransaction* transaction() const; /** * Forces a reload of the underlying datasource if the provider implements this * method. * In particular on the OGR provider, a pooled connection will be invalidated. * This forces QGIS to reopen a file or connection. * This can be required if the underlying file is replaced. */ virtual void forceReload(); /** * Get the list of layer ids on which this layer depends. This in particular determines the order of layer loading. */ virtual QSet layerDependencies() const; signals: /** Signals an error in this provider */ void raiseError( const QString& msg ); protected: void clearMinMaxCache(); //! Populates the cache of minimum and maximum attribute values. void fillMinMaxCache() const; void pushError( const QString& msg ); /** Converts the geometry to the provider type if possible / necessary @return the converted geometry or nullptr if no conversion was necessary or possible*/ QgsGeometry* convertToProviderType( const QgsGeometry& geom ) const /Factory/; }; QFlags operator|(QgsVectorDataProvider::Capability f1, QFlags f2);