Abstract base class for spatial data provider implementations. More...

#include <qgsdataprovider.h>

Inheritance diagram for QgsDataProvider:

Public Types
enum	DataCapability { NoDataCapabilities = 0, File = 1, Dir = 1 << 1, Database = 1 << 2, Net = 1 << 3 }

enum	ProviderProperty { EvaluateDefaultValues, CustomData = 3000 }
	Properties are used to pass custom configuration options into data providers. More...

Signals
void	dataChanged ()
	This is emitted whenever an asynchronous operation has finished and the data should be redrawn. More...

void	dataChanged (int changed)
	This is emitted whenever data or metadata (e.g. More...

void	fullExtentCalculated ()
	This is emitted whenever the worker thread has fully calculated the PostGIS extents for this layer, and its event has been received by this provider. More...

Public Member Functions
	QgsDataProvider (QString const &uri="")

virtual	~QgsDataProvider ()
	We need this so the subclass destructors get called. More...

virtual QgsCoordinateReferenceSystem	crs ()=0
	Get the QgsCoordinateReferenceSystem for this layer. More...

virtual QString	dataSourceUri (bool expandAuthConfig=false) const
	Get the data source specification. More...

virtual QDateTime	dataTimestamp () const
	Current time stamp of data source. More...

virtual QString	description () const =0
	Return description. More...

virtual bool	enterUpdateMode ()
	Enter update mode. More...

virtual QgsError	error () const
	Get current status error. More...

virtual QgsRectangle	extent ()=0
	Get the extent of the layer. More...

virtual QString	fileRasterFilters () const
	Return raster file filter string. More...

virtual QString	fileVectorFilters () const
	Return vector file filter string. More...

virtual void	invalidateConnections (const QString &connection)
	Invalidate connections corresponding to specified name. More...

virtual bool	isValid ()=0
	Returns true if this is a valid layer. More...

virtual bool	leaveUpdateMode ()
	Leave update mode. More...

virtual QString	name () const =0
	Return a provider name. More...

QVariant	providerProperty (ProviderProperty property, const QVariant &defaultValue=QVariant()) const
	Get the current value of a certain provider property. More...

QVariant	providerProperty (int property, const QVariant &defaultValue) const
	Get the current value of a certain provider property. More...

virtual void	reloadData ()
	Reloads the data from the source. More...

virtual void	setDataSourceUri (const QString &uri)
	Set the data source specification. More...

virtual void	setLayerOrder (const QStringList &layers)
	Reorder the list of layer names to be rendered by this provider (in order from bottom to top) More...

void	setProviderProperty (ProviderProperty property, const QVariant &value)
	Allows setting arbitrary properties on the provider. More...

void	setProviderProperty (int property, const QVariant &value)
	Allows setting arbitrary properties on the provider. More...

virtual void	setSubLayerVisibility (const QString &name, bool vis)
	Set the visibility of the given sublayer name. More...

virtual bool	setSubsetString (const QString &subset, bool updateFeatureCount=true)
	Set the subset string used to create a subset of features in the layer. More...

virtual uint	subLayerCount () const
	return the number of layers for the current data source More...

virtual QStringList	subLayers () const
	Sub-layers handled by this provider, in order from bottom to top. More...

virtual QStringList	subLayerStyles () const
	Sub-layer styles for each sub-layer handled by this provider, in order from bottom to top. More...

virtual QString	subsetString ()
	Returns the subset definition string (typically sql) currently in use by the layer and used by the provider to limit the feature set. More...

virtual bool	supportsSubsetString ()
	Provider supports setting of subset strings. More...

virtual QDateTime	timestamp () const
	Time stamp of data source in the moment when data/metadata were loaded by provider. More...

virtual void	updateExtents ()
	Update the extents of the layer. More...

Public Member Functions inherited from QObject
	QObject (QObject *parent)

	QObject (QObject parent, const char name)

virtual	~QObject ()

bool	blockSignals (bool block)

QObject *	child (const char objName, const char inheritsClass, bool recursiveSearch) const

const QObjectList &	children () const

const char *	className () const

bool	connect (const QObject sender, const char signal, const char *method, Qt::ConnectionType type) const

void	deleteLater ()

void	destroyed (QObject *obj)

bool	disconnect (const QObject receiver, const char method)

bool	disconnect (const char signal, const QObject receiver, const char *method)

void	dumpObjectInfo ()

void	dumpObjectTree ()

QList< QByteArray >	dynamicPropertyNames () const

virtual bool	event (QEvent *e)

virtual bool	eventFilter (QObject watched, QEvent event)

T	findChild (const QString &name) const

QList< T >	findChildren (const QRegExp &regExp) const

QList< T >	findChildren (const QString &name) const

bool	inherits (const char *className) const

void	insertChild (QObject *object)

void	installEventFilter (QObject *filterObj)

bool	isA (const char *className) const

bool	isWidgetType () const

void	killTimer (int id)

virtual const QMetaObject *	metaObject () const

void	moveToThread (QThread *targetThread)

const char *	name () const

const char *	name (const char *defaultName) const

QString	objectName () const

QObject *	parent () const

QVariant	property (const char *name) const

void	removeChild (QObject *object)

void	removeEventFilter (QObject *obj)

void	setName (const char *name)

void	setObjectName (const QString &name)

void	setParent (QObject *parent)

bool	setProperty (const char *name, const QVariant &value)

bool	signalsBlocked () const

int	startTimer (int interval)

QThread *	thread () const

Protected Member Functions
void	appendError (const QgsErrorMessage &theMessage)
	Add error message. More...

void	setError (const QgsError &theError)
	Set error message. More...

Protected Member Functions inherited from QObject
bool	checkConnectArgs (const char signal, const QObject object, const char *method)

virtual void	childEvent (QChildEvent *event)

virtual void	connectNotify (const char *signal)

virtual void	customEvent (QEvent *event)

virtual void	disconnectNotify (const char *signal)

int	receivers (const char *signal) const

QObject *	sender () const

int	senderSignalIndex () const

virtual void	timerEvent (QTimerEvent *event)

Protected Attributes
QgsError	mError
	Error. More...

QDateTime	mTimestamp
	Timestamp of data in the moment when the data were loaded by provider. More...

Additional Inherited Members
Static Public Member Functions inherited from QObject
bool	connect (const QObject sender, const char signal, const QObject receiver, const char method, Qt::ConnectionType type)

bool	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type)

bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char method)

bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method)

QString	tr (const char sourceText, const char disambiguation, int n)

QString	trUtf8 (const char sourceText, const char disambiguation, int n)

Static Protected Member Functions inherited from QObject
QByteArray	normalizeSignalSlot (const char *signalSlot)

Properties inherited from QObject
	objectName

Detailed Description

Abstract base class for spatial data provider implementations.

Author: Gary E.Sherman

This object needs to inherit from QObject to enable event processing in the Postgres/PostGIS provider (QgsPostgresProvider). It is called here so that this vtable and the vtable for QgsPostgresProvider don't get misaligned - the QgsVectorLayer class factory (which refers to generic QgsVectorDataProvider's) depends on it.

Definition at line 47 of file qgsdataprovider.h.

Member Enumeration Documentation

◆ DataCapability

enum QgsDataProvider::DataCapability

Enumerator
NoDataCapabilities
File
Dir
Database
Net

Definition at line 55 of file qgsdataprovider.h.

◆ ProviderProperty

enum QgsDataProvider::ProviderProperty

Properties are used to pass custom configuration options into data providers.

This enum defines a list of custom properties which can be used on different providers. It depends on the provider, which properties are supported. In addition to these default properties, providers can add their custom properties starting from CustomData.

Enumerator
EvaluateDefaultValues	Evaluate default values on provider side when calling QgsVectorDataProvider::defaultValue( int index ) rather than on commit.
CustomData	Custom properties for 3rd party providers or very provider-specific properties which are not expected to be of interest for other providers can be added starting from this value up.

Definition at line 71 of file qgsdataprovider.h.

Constructor & Destructor Documentation

◆ QgsDataProvider()

QgsDataProvider::QgsDataProvider ( QString const & uri = "" )

inline

Definition at line 77 of file qgsdataprovider.h.

◆ ~QgsDataProvider()

virtual QgsDataProvider::~QgsDataProvider ( )

inlinevirtual

We need this so the subclass destructors get called.

Definition at line 84 of file qgsdataprovider.h.

Member Function Documentation

◆ appendError()

void QgsDataProvider::appendError ( const QgsErrorMessage & theMessage )

inlineprotected

Add error message.

Definition at line 434 of file qgsdataprovider.h.

◆ crs()

virtual QgsCoordinateReferenceSystem QgsDataProvider::crs ( )

pure virtual

Get the QgsCoordinateReferenceSystem for this layer.

Note: Must be reimplemented by each provider. If the provider isn't capable of returning its projection an empty srs will be return, ti will return 0

◆ dataChanged [1/2]

void QgsDataProvider::dataChanged ( )

signal

This is emitted whenever an asynchronous operation has finished and the data should be redrawn.

When emitted from a QgsVectorDataProvider, any cached information such as feature ids should be invalidated.

◆ dataChanged [2/2]

void QgsDataProvider::dataChanged ( int changed )

signal

This is emitted whenever data or metadata (e.g.

color table, extent) has changed

Parameters

changed binary combination of changes

◆ dataSourceUri()

virtual QString QgsDataProvider::dataSourceUri ( bool expandAuthConfig = false ) const

inlinevirtual

Get the data source specification.

This may be a path or database connection string

Parameters

expandAuthConfig Whether to expand any assigned authentication configuration

Returns: data source specification

Note: The default authentication configuration expansion is FALSE. This keeps credentials out of layer data source URIs and project files. Expansion should be specifically done only when needed within a provider

Definition at line 114 of file qgsdataprovider.h.

◆ dataTimestamp()

virtual QDateTime QgsDataProvider::dataTimestamp ( ) const

inlinevirtual

Current time stamp of data source.

Reimplemented in QgsRasterDataProvider.

Definition at line 314 of file qgsdataprovider.h.

◆ description()

virtual QString QgsDataProvider::description ( ) const

pure virtual

Return description.

Return a terse string describing what the provider is.

Note

Instead of being pure virtual, might be better to generalize this behavior and presume that none of the sub-classes are going to do anything strange with regards to their name or description?

◆ enterUpdateMode()

virtual bool QgsDataProvider::enterUpdateMode ( )

inlinevirtual

Enter update mode.

This is aimed at providers that can open differently the connection to the datasource, according it to be in update mode or in read-only mode. A call to this method shall be balanced with a call to leaveUpdateMode(), if this method returns true.

Most providers will have an empty implementation for that method.

For backward compatibility, providers that implement enterUpdateMode() should still make sure to allow editing operations to work even if enterUpdateMode() is not explicitly called.

Several successive calls to enterUpdateMode() can be done. So there is a concept of stack of calls that must be handled by the provider. Only the first call to enterUpdateMode() will really turn update mode on.

Returns: true in case of success (or no-op implementation), false in case of failure.

Note: added in QGIS 2.16

Definition at line 348 of file qgsdataprovider.h.

◆ error()

virtual QgsError QgsDataProvider::error ( ) const

inlinevirtual

Get current status error.

This error describes some principal problem for which provider cannot work and thus is not valid. It is not last error after accessing data by block(), identify() etc.

Definition at line 320 of file qgsdataprovider.h.

◆ extent()

virtual QgsRectangle QgsDataProvider::extent ( )

pure virtual

Get the extent of the layer.

Returns: QgsRectangle containing the extent of the layer

Implemented in QgsRasterDataProvider.

◆ fileRasterFilters()

virtual QString QgsDataProvider::fileRasterFilters ( ) const

inlinevirtual

Return raster file filter string.

Returns a string suitable for a QFileDialog of raster file formats supported by the data provider. Naturally this will be an empty string for those data providers that do not deal with plain files, such as databases and servers.

Note: It'd be nice to eventually be raster/vector neutral.

Definition at line 300 of file qgsdataprovider.h.

◆ fileVectorFilters()

virtual QString QgsDataProvider::fileVectorFilters ( ) const

inlinevirtual

Return vector file filter string.

Returns a string suitable for a QFileDialog of vector file formats supported by the data provider. Naturally this will be an empty string for those data providers that do not deal with plain files, such as databases and servers.

Note: It'd be nice to eventually be raster/vector neutral.

Definition at line 285 of file qgsdataprovider.h.

◆ fullExtentCalculated

void QgsDataProvider::fullExtentCalculated ( )

signal

This is emitted whenever the worker thread has fully calculated the PostGIS extents for this layer, and its event has been received by this provider.

◆ invalidateConnections()

virtual void QgsDataProvider::invalidateConnections ( const QString & connection )

inlinevirtual

Invalidate connections corresponding to specified name.

Note: added in QGIS 2.16

Definition at line 325 of file qgsdataprovider.h.

◆ isValid()

virtual bool QgsDataProvider::isValid ( )

pure virtual

Returns true if this is a valid layer.

It is up to individual providers to determine what constitutes a valid layer

◆ leaveUpdateMode()

virtual bool QgsDataProvider::leaveUpdateMode ( )

inlinevirtual

Leave update mode.

This is aimed at providers that can open differently the connection to the datasource, according it to be in update mode or in read-only mode. This method shall be balanced with a successful call to enterUpdateMode().

Most providers will have an empty implementation for that method.

Several successive calls to enterUpdateMode() can be done. So there is a concept of stack of calls that must be handled by the provider. Only the last call to leaveUpdateMode() will really turn update mode off.

Returns: true in case of success (or no-op implementation), false in case of failure.

Note: added in QGIS 2.16

Definition at line 366 of file qgsdataprovider.h.

◆ name()

virtual QString QgsDataProvider::name ( ) const

pure virtual

Return a provider name.

Essentially just returns the provider key. Should be used to build file dialogs so that providers can be shown with their supported types. Thus if more than one provider supports a given format, the user is able to select a specific provider to open that file.

Note

Instead of being pure virtual, might be better to generalize this behavior and presume that none of the sub-classes are going to do anything strange with regards to their name or description?

◆ providerProperty() [1/2]

QVariant QgsDataProvider::providerProperty	(	QgsDataProvider::ProviderProperty	property,
		const QVariant &	defaultValue = `QVariant()`
	)		const

Get the current value of a certain provider property.

It depends on the provider which properties are supported.

Note: added in 2.16

Definition at line 29 of file qgsdataprovider.cpp.

◆ providerProperty() [2/2]

QVariant QgsDataProvider::providerProperty	(	int	property,
		const QVariant &	defaultValue = `QVariant()`
	)		const

Get the current value of a certain provider property.

It depends on the provider which properties are supported.

Note: added in 2.16

Definition at line 34 of file qgsdataprovider.cpp.

◆ reloadData()

virtual void QgsDataProvider::reloadData ( )

inlinevirtual

Reloads the data from the source.

Needs to be implemented by providers with data caches to synchronize with changes in the data source

Definition at line 308 of file qgsdataprovider.h.

◆ setDataSourceUri()

virtual void QgsDataProvider::setDataSourceUri ( const QString & uri )

inlinevirtual

Set the data source specification.

This may be a path or database connection string

Parameters

uri	source specification

Definition at line 100 of file qgsdataprovider.h.

◆ setError()

void QgsDataProvider::setError ( const QgsError & theError )

inlineprotected

Set error message.

Definition at line 437 of file qgsdataprovider.h.

◆ setLayerOrder()

virtual void QgsDataProvider::setLayerOrder ( const QStringList & layers )

inlinevirtual

Reorder the list of layer names to be rendered by this provider (in order from bottom to top)

Note: layers must have been previously added.

Definition at line 220 of file qgsdataprovider.h.

◆ setProviderProperty() [1/2]

void QgsDataProvider::setProviderProperty	(	QgsDataProvider::ProviderProperty	property,
		const QVariant &	value
	)

Allows setting arbitrary properties on the provider.

It depends on the provider which properties are supported.

Note: added in 2.16

Definition at line 19 of file qgsdataprovider.cpp.

◆ setProviderProperty() [2/2]

void QgsDataProvider::setProviderProperty	(	int	property,
		const QVariant &	value
	)

Allows setting arbitrary properties on the provider.

It depends on the provider which properties are supported.

Note: added in 2.16

Definition at line 24 of file qgsdataprovider.cpp.

◆ setSubLayerVisibility()

virtual void QgsDataProvider::setSubLayerVisibility	(	const QString &	name,
		bool	vis
	)

inlinevirtual

Set the visibility of the given sublayer name.

Definition at line 234 of file qgsdataprovider.h.

◆ setSubsetString()

virtual bool QgsDataProvider::setSubsetString	(	const QString &	subset,
		bool	updateFeatureCount = `true`
	)

inlinevirtual

Set the subset string used to create a subset of features in the layer.

This may be a sql where clause or any other string that can be used by the data provider to create a subset. Must be implemented in the dataprovider.

Definition at line 157 of file qgsdataprovider.h.

◆ subLayerCount()

virtual uint QgsDataProvider::subLayerCount ( ) const

inlinevirtual

return the number of layers for the current data source

Definition at line 209 of file qgsdataprovider.h.

◆ subLayers()

virtual QStringList QgsDataProvider::subLayers ( ) const

inlinevirtual

Sub-layers handled by this provider, in order from bottom to top.

Sub-layers are used when the provider's source can combine layers it knows about in some way before it hands them off to the provider.

Reimplemented in QgsRasterDataProvider.

Definition at line 187 of file qgsdataprovider.h.

◆ subLayerStyles()

virtual QStringList QgsDataProvider::subLayerStyles ( ) const

inlinevirtual

Sub-layer styles for each sub-layer handled by this provider, in order from bottom to top.

Sub-layer styles are used to abstract the way the provider's source can symbolise layers in some way at the server, before it serves them to the provider.

Definition at line 200 of file qgsdataprovider.h.

◆ subsetString()

virtual QString QgsDataProvider::subsetString ( )

inlinevirtual

Returns the subset definition string (typically sql) currently in use by the layer and used by the provider to limit the feature set.

Must be overridden in the dataprovider, otherwise returns a null QString.

Definition at line 175 of file qgsdataprovider.h.

◆ supportsSubsetString()

virtual bool QgsDataProvider::supportsSubsetString ( )

inlinevirtual

Provider supports setting of subset strings.

Definition at line 167 of file qgsdataprovider.h.

◆ timestamp()

virtual QDateTime QgsDataProvider::timestamp ( ) const

inlinevirtual

Time stamp of data source in the moment when data/metadata were loaded by provider.

Reimplemented in QgsRasterDataProvider.

Definition at line 311 of file qgsdataprovider.h.

◆ updateExtents()

virtual void QgsDataProvider::updateExtents ( )

inlinevirtual

Update the extents of the layer.

Not implemented by default

Definition at line 145 of file qgsdataprovider.h.

Member Data Documentation

◆ mError

QgsError QgsDataProvider::mError

protected

Error.

Definition at line 431 of file qgsdataprovider.h.

◆ mTimestamp

QDateTime QgsDataProvider::mTimestamp

protected

Timestamp of data in the moment when the data were loaded by provider.

Definition at line 428 of file qgsdataprovider.h.

The documentation for this class was generated from the following files:

/tmp/buildd/qgis-2.18.21+99unstable/src/core/qgsdataprovider.h
/tmp/buildd/qgis-2.18.21+99unstable/src/core/qgsdataprovider.cpp

Public Types

Signals

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ DataCapability

◆ ProviderProperty

Constructor & Destructor Documentation

◆ QgsDataProvider()

◆ ~QgsDataProvider()

Member Function Documentation

◆ appendError()

◆ crs()

◆ dataChanged [1/2]

◆ dataChanged [2/2]

◆ dataSourceUri()

◆ dataTimestamp()

◆ description()

◆ enterUpdateMode()

◆ error()

◆ extent()

◆ fileRasterFilters()

◆ fileVectorFilters()

◆ fullExtentCalculated

◆ invalidateConnections()

◆ isValid()

◆ leaveUpdateMode()

◆ name()

◆ providerProperty() [1/2]

◆ providerProperty() [2/2]

◆ reloadData()

◆ setDataSourceUri()

◆ setError()

◆ setLayerOrder()

◆ setProviderProperty() [1/2]

◆ setProviderProperty() [2/2]

◆ setSubLayerVisibility()

◆ setSubsetString()

◆ subLayerCount()

◆ subLayers()

◆ subLayerStyles()

◆ subsetString()

◆ supportsSubsetString()

◆ timestamp()

◆ updateExtents()

Member Data Documentation

◆ mError

◆ mTimestamp