This is the base class for vector data providers. More...

#include <qgsvectordataprovider.h>

Inheritance diagram for QgsVectorDataProvider:

Collaboration diagram for QgsVectorDataProvider:

Classes
struct	NativeType
Public Types
enum	Capability { NoCapabilities = 0, AddFeatures = 1, DeleteFeatures = 1 << 1, ChangeAttributeValues = 1 << 2, AddAttributes = 1 << 3, DeleteAttributes = 1 << 4, SaveAsShapefile = 1 << 5, CreateSpatialIndex = 1 << 6, SelectAtId = 1 << 7, ChangeGeometries = 1 << 8, SelectGeometryAtId = 1 << 9, RandomSelectGeometryAtId = 1 << 10, SequentialSelectGeometryAtId = 1 << 11, CreateAttributeIndex = 1 << 12, SelectEncoding = 1 << 13 }
	enumeration with capabilities that providers might implement More...
Public Member Functions
	QgsVectorDataProvider (QString uri=QString())
	Constructor of the vector provider.
virtual	~QgsVectorDataProvider ()
	Destructor.
virtual bool	addAttributes (const QList< QgsField > &attributes)
	Adds new attributes.
virtual bool	addFeatures (QgsFeatureList &flist)
	Adds a list of features.
virtual QgsAttributeList	attributeIndexes ()
	Return list of indexes to fetch all attributes in nextFeature()
virtual int	capabilities () const
	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.
QString	capabilitiesString () const
	Returns the above in friendly format.
virtual bool	changeAttributeValues (const QgsChangedAttributesMap &attr_map)
	Changes attribute values of existing features.
virtual bool	changeGeometryValues (QgsGeometryMap &geometry_map)
	Changes geometries of existing features.
void	clearErrors ()
virtual bool	createAttributeIndex (int field)
	Create an attribute index on the datasource.
virtual bool	createSpatialIndex ()
	Creates a spatial index on the datasource (if supported by the provider type).
virtual QString	dataComment () const
	Return a short comment for the data that this provider is providing access to (e.g.
virtual QVariant	defaultValue (int fieldId)
	Returns the default value for field specified by `fieldId`.
virtual bool	deleteAttributes (const QgsAttributeIds &attributes)
	Deletes existing attributes.
virtual bool	deleteFeatures (const QgsFeatureIds &id)
	Deletes one or more features.
virtual bool	doesStrictFeatureTypeCheck () const
	Returns true if the provider is strict about the type of inserted features (e.g.
QString	encoding () const
	Get encoding which is used for accessing data.
virtual void	enumValues (int index, QStringList &enumList)
	Returns the possible enum values of an attribute.
QStringList	errors ()
virtual long	featureCount () const =0
	Number of features in the layer.
int	fieldNameIndex (const QString &fieldName) const
	Returns the index of a field name or -1 if the field does not exist.
QMap< QString, int >	fieldNameMap () const
	Return a map where the key is the name of the field and the value is its index.
virtual const QgsFields &	fields () const =0
	Return a map of indexes with field names for this layer.
virtual QGis::WkbType	geometryType () const =0
	Get feature type.
virtual QgsFeatureIterator	getFeatures (const QgsFeatureRequest &request=QgsFeatureRequest())=0
	Query the provider for features specified in request.
bool	hasErrors ()
virtual bool	isSaveAndLoadStyleToDBSupported ()
	It returns false by default.
virtual QVariant	maximumValue (int index)
	Returns the maximum value of an attribute.
virtual QVariant	minimumValue (int index)
	Returns the minimum value of an attribute.
const QList< NativeType > &	nativeTypes () const
	Returns the names of the supported types.
virtual QgsAttrPalIndexNameHash	palAttributeIndexNames () const
	Return list of indexes to names for QgsPalLabeling fix.
virtual QgsAttributeList	pkAttributeIndexes ()
	Return list of indexes of fields that make up the primary key.
virtual void	setEncoding (const QString &e)
	Set encoding used for accessing data from layer.
virtual QString	storageType () const
	Returns the permanent storage type for this layer as a friendly name.
bool	supportedType (const QgsField &field) const
	check if provider supports type of field
virtual void	uniqueValues (int index, QList< QVariant > &uniqueValues, int limit=-1)
	Return unique values of an attribute.
Static Public Member Functions
static const QStringList &	availableEncodings ()
	Returns a list of available encodings.
Static Public Attributes
static const int	EditingCapabilities
	bitmask of all provider's editing capabilities
Protected Member Functions
void	clearMinMaxCache ()
QVariant	convertValue (QVariant::Type type, QString value)
void	fillMinMaxCache ()
void	pushError (QString msg)
Protected Attributes
QgsAttributeList	mAttributesToFetch
	List of attribute indices to fetch with nextFeature calls.
QgsAttrPalIndexNameHash	mAttrPalIndexName
	Old-style mapping of index to name for QgsPalLabeling fix.
QMap< int, QVariant >	mCacheMaxValues
bool	mCacheMinMaxDirty
QMap< int, QVariant >	mCacheMinValues
QTextCodec *	mEncoding
	Encoding.
bool	mFetchFeaturesWithoutGeom
	should provider fetch also features that don't have geometry?
bool	mFetchGeom
	True if geometry should be added to the features in nextFeature calls.
QList< NativeType >	mNativeTypes
	The names of the providers native types.
Private Attributes
QStringList	mErrors
QMap< QString, QVariant::Type >	mOldTypeList
	old notation
Static Private Attributes
static QStringList	smEncodings

Detailed Description

This is the base class for vector data providers.

Data providers abstract the retrieval and writing (where supported) of feature and attribute information from a spatial datasource.

Definition at line 48 of file qgsvectordataprovider.h.

Member Enumeration Documentation

enum QgsVectorDataProvider::Capability

enumeration with capabilities that providers might implement

Enumerator:

NoCapabilities	provider has no capabilities
AddFeatures	allows adding features
DeleteFeatures	allows deletion of features
ChangeAttributeValues	allows modification of attribute values
AddAttributes	allows addition of new attributes (fields)
DeleteAttributes	allows deletion of attributes (fields)
SaveAsShapefile	DEPRECATED - do not use.
CreateSpatialIndex	allows creation of spatial index
SelectAtId	fast access to features using their ID
ChangeGeometries	allows modifications of geometries
SelectGeometryAtId	DEPRECATED - do not use.
RandomSelectGeometryAtId	DEPRECATED - do not use.
SequentialSelectGeometryAtId	DEPRECATED - do not use.
CreateAttributeIndex
SelectEncoding	allows user to select encoding

Definition at line 58 of file qgsvectordataprovider.h.

Constructor & Destructor Documentation

QgsVectorDataProvider::QgsVectorDataProvider ( QString uri = QString() )

Constructor of the vector provider.

Parameters:

uri	uniform resource locator (URI) for a dataset

Definition at line 30 of file qgsvectordataprovider.cpp.

References setEncoding().

QgsVectorDataProvider::~QgsVectorDataProvider ( ) [virtual]

Destructor.

Definition at line 40 of file qgsvectordataprovider.cpp.

Member Function Documentation

bool QgsVectorDataProvider::addAttributes ( const QList< QgsField > & attributes ) [virtual]

Adds new attributes.

Parameters:

attributes list of new attributes

Returns:: true in case of success and false in case of failure

Note:: added in 1.2

Definition at line 66 of file qgsvectordataprovider.cpp.

Referenced by QgsZonalStatistics::calculateStatistics(), QgsVectorLayerEditBuffer::commitChanges(), and QgsGeometryAnalyzer::eventLayer().

bool QgsVectorDataProvider::addFeatures ( QgsFeatureList & flist ) [virtual]

Adds a list of features.

Returns:: true in case of success and false in case of failure

Definition at line 54 of file qgsvectordataprovider.cpp.

Referenced by QgsVectorLayerEditBuffer::commitChanges(), QgsGeometryAnalyzer::eventLayer(), and QgsVectorLayerImport::flushBuffer().

QgsAttributeList QgsVectorDataProvider::attributeIndexes ( ) [virtual]

Return list of indexes to fetch all attributes in nextFeature()

Definition at line 229 of file qgsvectordataprovider.cpp.

References QgsFields::count(), and fields().

const QStringList & QgsVectorDataProvider::availableEncodings ( ) [static]

Returns a list of available encodings.

Definition at line 406 of file qgsvectordataprovider.cpp.

References _compareEncodings(), and smEncodings.

Referenced by QgsEncodingFileDialog::QgsEncodingFileDialog().

int QgsVectorDataProvider::capabilities ( ) const [virtual]

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.

Definition at line 107 of file qgsvectordataprovider.cpp.

References NoCapabilities.

QString QgsVectorDataProvider::capabilitiesString ( ) const

Returns the above in friendly format.

Definition at line 142 of file qgsvectordataprovider.cpp.

References AddAttributes, AddFeatures, capabilities(), ChangeAttributeValues, ChangeGeometries, CreateSpatialIndex, DeleteAttributes, DeleteFeatures, QgsDebugMsg, SelectAtId, and tr.

Referenced by QgsVectorLayer::capabilitiesString().

bool QgsVectorDataProvider::changeAttributeValues ( const QgsChangedAttributesMap & attr_map ) [virtual]

Changes attribute values of existing features.

Parameters:

attr_map a map containing changed attributes

Returns:: true in case of success and false in case of failure

Definition at line 78 of file qgsvectordataprovider.cpp.

Referenced by QgsZonalStatistics::calculateStatistics(), and QgsVectorLayerEditBuffer::commitChanges().

bool QgsVectorDataProvider::changeGeometryValues ( QgsGeometryMap & geometry_map ) [virtual]

Changes geometries of existing features.

Parameters:

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

Returns:: True in case of success and false in case of failure

Definition at line 90 of file qgsvectordataprovider.cpp.

Referenced by QgsVectorLayerEditBuffer::commitChanges().

void QgsVectorDataProvider::clearErrors ( )

Definition at line 469 of file qgsvectordataprovider.cpp.

References mErrors.

Referenced by QgsQueryBuilder::accept(), QgsVectorLayerEditBuffer::commitChanges(), QgsVectorLayerImport::flushBuffer(), and QgsQueryBuilder::test().

void QgsVectorDataProvider::clearMinMaxCache ( ) [protected]

Definition at line 316 of file qgsvectordataprovider.cpp.

References mCacheMinMaxDirty.

QVariant QgsVectorDataProvider::convertValue	(	QVariant::Type	type,
		QString	value
	)		`[protected]`

Definition at line 391 of file qgsvectordataprovider.cpp.

bool QgsVectorDataProvider::createAttributeIndex ( int field ) [virtual]

Create an attribute index on the datasource.

Definition at line 101 of file qgsvectordataprovider.cpp.

bool QgsVectorDataProvider::createSpatialIndex ( ) [virtual]

Creates a spatial index on the datasource (if supported by the provider type).

Returns:: true in case of success

Definition at line 96 of file qgsvectordataprovider.cpp.

Referenced by QgsVectorLayerImport::createSpatialIndex().

QString QgsVectorDataProvider::dataComment ( ) const [virtual]

Return a short comment for the data that this provider is providing access to (e.g.

the comment for postgres table).

Definition at line 49 of file qgsvectordataprovider.cpp.

Referenced by QgsVectorLayer::dataComment().

QVariant QgsVectorDataProvider::defaultValue ( int fieldId ) [virtual]

Returns the default value for field specified by fieldId.

Definition at line 84 of file qgsvectordataprovider.cpp.

Referenced by QgsVectorLayerEditUtils::splitFeatures().

bool QgsVectorDataProvider::deleteAttributes ( const QgsAttributeIds & attributes ) [virtual]

Deletes existing attributes.

Parameters:

attributes a set containing indices of attributes

Returns:: true in case of success and false in case of failure

Definition at line 72 of file qgsvectordataprovider.cpp.

Referenced by QgsVectorLayerEditBuffer::commitChanges().

bool QgsVectorDataProvider::deleteFeatures ( const QgsFeatureIds & id ) [virtual]

Deletes one or more features.

Parameters:

id	list containing feature ids to delete

Returns:: true in case of success and false in case of failure

Definition at line 60 of file qgsvectordataprovider.cpp.

Referenced by QgsVectorLayerEditBuffer::commitChanges().

virtual bool QgsVectorDataProvider::doesStrictFeatureTypeCheck ( ) const [inline, virtual]

Returns true if the provider is strict about the type of inserted features (e.g.

no multipolygon in a polygon layer)

Note:: : added in version 1.4

Definition at line 311 of file qgsvectordataprovider.h.

QString QgsVectorDataProvider::encoding ( ) const

Get encoding which is used for accessing data.

Definition at line 132 of file qgsvectordataprovider.cpp.

References mEncoding.

Referenced by QgsGeometryAnalyzer::buffer(), QgsGeometryAnalyzer::centroids(), QgsGeometryAnalyzer::convexHull(), QgsGeometryAnalyzer::dissolve(), QgsGeometryAnalyzer::eventLayer(), QgsGeometryAnalyzer::extent(), QgsOverlayAnalyzer::intersection(), QgsGeometryAnalyzer::simplify(), and QgsVectorLayer::writeXml().

virtual void QgsVectorDataProvider::enumValues	(	int	index,
		QStringList &	enumList
	)		`[inline, virtual]`

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.

Parameters:

index	the index of the attribute
enumList	reference to the list to fill

Note:: : added in version 1.2

Definition at line 176 of file qgsvectordataprovider.h.

Referenced by QgsAttributeEditor::createAttributeEditor().

QStringList QgsVectorDataProvider::errors ( )

Definition at line 479 of file qgsvectordataprovider.cpp.

References mErrors.

Referenced by QgsQueryBuilder::accept(), QgsVectorLayerEditBuffer::commitChanges(), QgsVectorLayerImport::flushBuffer(), and QgsQueryBuilder::test().

virtual long QgsVectorDataProvider::featureCount ( ) const [pure virtual]

Number of features in the layer.

Returns:: long containing number of features

Referenced by QgsZonalStatistics::calculateStatistics(), QgsVectorLayer::extent(), QgsVectorLayer::featureCount(), and QgsVectorLayer::pendingFeatureCount().

int QgsVectorDataProvider::fieldNameIndex ( const QString & fieldName ) const

Returns the index of a field name or -1 if the field does not exist.

Definition at line 202 of file qgsvectordataprovider.cpp.

References QgsFields::count(), fields(), and QgsDataProvider::name().

Referenced by QgsZonalStatistics::calculateStatistics().

QMap< QString, int > QgsVectorDataProvider::fieldNameMap ( ) const

Return a map where the key is the name of the field and the value is its index.

Definition at line 216 of file qgsvectordataprovider.cpp.

References QgsFields::count(), fields(), and QgsDataProvider::name().

Referenced by QgsVectorLayer::attributeEditorElementFromDomElement().

virtual const QgsFields& QgsVectorDataProvider::fields ( ) const [pure virtual]

Return a map of indexes with field names for this layer.

Returns:: map of fields

See also:: QgsFieldMap

Referenced by QgsVectorLayerEditBuffer::addFeature(), attributeIndexes(), QgsOfflineEditing::copyVectorLayer(), fieldNameIndex(), fieldNameMap(), fillMinMaxCache(), maximumValue(), minimumValue(), QgsPalLayerSettings::readDataDefinedProperty(), QgsVectorLayer::setDataProvider(), QgsFeatureListModel::setDisplayExpression(), QgsProjectFileTransform::transform0110to1000(), and QgsVectorLayer::updateFields().

void QgsVectorDataProvider::fillMinMaxCache ( ) [protected]

Definition at line 321 of file qgsvectordataprovider.cpp.

References QgsFeature::attributes(), QgsFields::count(), fields(), getFeatures(), isNull(), mCacheMaxValues, mCacheMinMaxDirty, mCacheMinValues, and QgsFeatureIterator::nextFeature().

Referenced by maximumValue(), and minimumValue().

virtual QGis::WkbType QgsVectorDataProvider::geometryType ( ) const [pure virtual]

Get feature type.

Returns:: int representing the feature type

Referenced by QgsGeometryAnalyzer::dissolve(), QgsVectorLayer::geometryType(), QgsOverlayAnalyzer::intersection(), QgsVectorLayer::setDataProvider(), and QgsGeometryAnalyzer::simplify().

virtual QgsFeatureIterator QgsVectorDataProvider::getFeatures ( const QgsFeatureRequest & request = QgsFeatureRequest() ) [pure virtual]

Query the provider for features specified in request.

Referenced by QgsZonalStatistics::calculateStatistics(), fillMinMaxCache(), QgsVectorLayerFeatureIterator::nextFeatureFid(), QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator(), uniqueValues(), and QgsVectorLayerFeatureIterator::useChangedAttributeFeature().

bool QgsVectorDataProvider::hasErrors ( )

Definition at line 474 of file qgsvectordataprovider.cpp.

References mErrors.

Referenced by QgsQueryBuilder::accept(), QgsVectorLayerEditBuffer::commitChanges(), and QgsQueryBuilder::test().

virtual bool QgsVectorDataProvider::isSaveAndLoadStyleToDBSupported ( ) [inline, virtual]

It returns false by default.

Must be implemented by providers that support saving and loading styles to db returning true

Definition at line 336 of file qgsvectordataprovider.h.

QVariant QgsVectorDataProvider::maximumValue ( int index ) [virtual]

Returns the maximum value of an attribute.

Parameters:

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.

Definition at line 277 of file qgsvectordataprovider.cpp.

References fields(), fillMinMaxCache(), mCacheMaxValues, and QgsDebugMsg.

Referenced by QgsVectorLayer::maximumValue().

QVariant QgsVectorDataProvider::minimumValue ( int index ) [virtual]

Returns the minimum value of an attribute.

Parameters:

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.

Definition at line 261 of file qgsvectordataprovider.cpp.

References fields(), fillMinMaxCache(), mCacheMinValues, and QgsDebugMsg.

Referenced by QgsVectorLayer::minimumValue().

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

Returns the names of the supported types.

Note:: added in 1.2

Definition at line 240 of file qgsvectordataprovider.cpp.

References mNativeTypes.

Referenced by QgsOfflineEditing::applyAttributesAdded().

virtual QgsAttrPalIndexNameHash QgsVectorDataProvider::palAttributeIndexNames ( ) const [inline, virtual]

Return list of indexes to names for QgsPalLabeling fix.

Definition at line 280 of file qgsvectordataprovider.h.

Referenced by QgsPalLayerSettings::readDataDefinedProperty().

virtual QgsAttributeList QgsVectorDataProvider::pkAttributeIndexes ( ) [inline, virtual]

Return list of indexes of fields that make up the primary key.

Note:: added in 2.0

Definition at line 275 of file qgsvectordataprovider.h.

Referenced by QgsVectorLayer::pendingPkAttributesList().

void QgsVectorDataProvider::pushError ( QString msg ) [protected]

Definition at line 484 of file qgsvectordataprovider.cpp.

References mErrors.

void QgsVectorDataProvider::setEncoding ( const QString & e ) [virtual]

Set encoding used for accessing data from layer.

Definition at line 113 of file qgsvectordataprovider.cpp.

References QgsMessageLog::logMessage(), mEncoding, and tr.

Referenced by QgsVectorDataProvider(), QgsVectorLayer::readXml(), and QgsVectorLayer::setProviderEncoding().

QString QgsVectorDataProvider::storageType ( ) const [virtual]

Returns the permanent storage type for this layer as a friendly name.

Definition at line 44 of file qgsvectordataprovider.cpp.

Referenced by QgsVectorLayer::storageType().

bool QgsVectorDataProvider::supportedType ( const QgsField & field ) const

check if provider supports type of field

Note:: added in 1.2

Definition at line 245 of file qgsvectordataprovider.cpp.

References QgsField::length(), mNativeTypes, QgsField::precision(), and QgsField::type().

Referenced by QgsVectorLayerEditBuffer::addAttribute().

void QgsVectorDataProvider::uniqueValues	(	int	index,
		QList< QVariant > &	uniqueValues,
		int	limit = `-1`
	)		`[virtual]`

Return unique values of an attribute.

Parameters:

index	the index of the attribute
uniqueValues	values reference to the list to fill
limit	maxmum number of the values to return (added in 1.4)

Default implementation simply iterates the features

Definition at line 293 of file qgsvectordataprovider.cpp.

References QgsFeature::attribute(), getFeatures(), and QgsFeatureIterator::nextFeature().

Referenced by QgsAttributeEditor::createAttributeEditor(), and QgsVectorLayer::uniqueValues().

Member Data Documentation

const int QgsVectorDataProvider::EditingCapabilities [static]

Initial value:

 AddFeatures | DeleteFeatures |
                                           ChangeAttributeValues | ChangeGeometries | AddAttributes | DeleteAttributes

bitmask of all provider's editing capabilities

Definition at line 92 of file qgsvectordataprovider.h.

Referenced by QgsVectorLayer::startEditing().

QgsAttributeList QgsVectorDataProvider::mAttributesToFetch [protected]

List of attribute indices to fetch with nextFeature calls.

Definition at line 357 of file qgsvectordataprovider.h.

QgsAttrPalIndexNameHash QgsVectorDataProvider::mAttrPalIndexName [protected]

Old-style mapping of index to name for QgsPalLabeling fix.

Definition at line 365 of file qgsvectordataprovider.h.

QMap<int, QVariant> QgsVectorDataProvider::mCacheMaxValues [protected]

Definition at line 345 of file qgsvectordataprovider.h.

Referenced by fillMinMaxCache(), and maximumValue().