Quantum GIS API Documentation
1.7.5-Wroclaw
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This is the base class for vector data providers. More...
#include <qgsvectordataprovider.h>
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, SetEncoding = 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 QString | storageType () const |
Returns the permanent storage type for this layer as a friendly name. | |
virtual void | select (QgsAttributeList fetchAttributes=QgsAttributeList(), QgsRectangle rect=QgsRectangle(), bool fetchGeometry=true, bool useIntersect=false)=0 |
Select features based on a bounding rectangle. | |
virtual long | updateFeatureCount () |
This function does nothing useful, it's kept only for compatibility. | |
virtual bool | featureAtId (int featureId, QgsFeature &feature, bool fetchGeometry=true, QgsAttributeList fetchAttributes=QgsAttributeList()) |
Gets the feature at the given feature ID. | |
virtual bool | nextFeature (QgsFeature &feature)=0 |
Get the next feature resulting from a select operation. | |
virtual QGis::WkbType | geometryType () const =0 |
Get feature type. | |
virtual long | featureCount () const =0 |
Number of features in the layer. | |
virtual uint | fieldCount () const =0 |
Number of attribute fields for a feature in the layer. | |
virtual const QgsFieldMap & | fields () const =0 |
Return a map of indexes with field names for this layer. | |
virtual QString | dataComment () const |
Return a short comment for the data that this provider is providing access to (e.g. | |
virtual void | rewind ()=0 |
Restart reading features from previous select operation. | |
virtual QVariant | minimumValue (int index) |
Returns the minimum value of an attribute. | |
virtual QVariant | maximumValue (int index) |
Returns the maximum value of an attribute. | |
virtual void | uniqueValues (int index, QList< QVariant > &uniqueValues, int limit=-1) |
Return unique values of an attribute. | |
virtual void | enumValues (int index, QStringList &enumList) |
Returns the possible enum values of an attribute. | |
virtual bool | addFeatures (QgsFeatureList &flist) |
Adds a list of features. | |
virtual bool | deleteFeatures (const QgsFeatureIds &id) |
Deletes one or more features. | |
virtual bool | addAttributes (const QList< QgsField > &attributes) |
Adds new attributes. | |
virtual Q_DECL_DEPRECATED bool | addAttributes (const QMap< QString, QString > &attributes) |
Add new attributes. | |
virtual bool | deleteAttributes (const QgsAttributeIds &attributes) |
Deletes existing attributes. | |
virtual bool | changeAttributeValues (const QgsChangedAttributesMap &attr_map) |
Changes attribute values of existing features. | |
virtual QVariant | defaultValue (int fieldId) |
Returns the default value for field specified by fieldId . | |
virtual bool | changeGeometryValues (QgsGeometryMap &geometry_map) |
Changes geometries of existing features. | |
virtual bool | createSpatialIndex () |
Creates a spatial index on the datasource (if supported by the provider type). | |
virtual bool | createAttributeIndex (int field) |
Create an attribute index on the datasource. | |
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 void | setEncoding (const QString &e) |
Set encoding used for accessing data from layer. | |
QString | encoding () const |
Get encoding which is used for accessing data. | |
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 QgsAttributeList | attributeIndexes () |
Return list of indexes to fetch all attributes in nextFeature() | |
void | enableGeometrylessFeatures (bool fetch) |
Set whether provider should also return features that don't have associated geometry. | |
bool | supportedType (const QgsField &field) const |
check if provider supports type of field | |
const QList< NativeType > & | nativeTypes () const |
Returns the names of the supported types. | |
Q_DECL_DEPRECATED const QMap < QString, QVariant::Type > & | supportedNativeTypes () const |
Returns the names of the supported types. | |
virtual bool | doesStrictFeatureTypeCheck () const |
Returns true if the provider is strict about the type of inserted features (e.g. | |
bool | hasErrors () |
void | clearErrors () |
QStringList | errors () |
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QgsDataProvider (QString const &uri="") | |
virtual | ~QgsDataProvider () |
We need this so the subclass destructors get called. | |
virtual QgsCoordinateReferenceSystem | crs ()=0 |
virtual void | setDataSourceUri (QString const &uri) |
Set the data source specification. | |
virtual QString | dataSourceUri () const |
Get the data source specification. | |
virtual QgsRectangle | extent ()=0 |
Get the extent of the layer. | |
virtual bool | isValid ()=0 |
Returns true if this is a valid layer. | |
virtual void | updateExtents () |
Update the extents of the layer. | |
virtual bool | setSubsetString (QString subset, bool updateFeatureCount=true) |
Set the subset string used to create a subset of features in the layer. | |
virtual bool | supportsSubsetString () |
provider supports setting of subset strings | |
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. | |
virtual QStringList | subLayers () const |
Sub-layers handled by this provider, in order from bottom to top. | |
virtual QStringList | subLayerStyles () const |
Sub-layer styles for each sub-layer handled by this provider, in order from bottom to top. | |
virtual uint | subLayerCount () const |
return the number of layers for the current data source | |
virtual void | setLayerOrder (QStringList layers) |
Reorder the list of layer names to be rendered by this provider (in order from bottom to top) | |
virtual void | setSubLayerVisibility (QString name, bool vis) |
Set the visibility of the given sublayer name. | |
virtual QString | name () const =0 |
return a provider name | |
virtual QString | description () const =0 |
return description | |
virtual QString | fileVectorFilters () const |
return vector file filter string | |
virtual QString | fileRasterFilters () const |
return raster file filter string | |
virtual void | reloadData () |
Reloads the data from the the source. | |
virtual QDateTime | timestamp () const |
Time stamp of data source in the moment when data/metadata were loaded by provider. | |
virtual QDateTime | dataTimestamp () const |
Current time stamp of data source. |
Static Public Member Functions | |
static const QStringList & | availableEncodings () |
Static Public Attributes | |
static const int | EditingCapabilities |
bitmask of all provider's editing capabilities |
Protected Member Functions | |
QVariant | convertValue (QVariant::Type type, QString value) |
void | clearMinMaxCache () |
void | fillMinMaxCache () |
void | pushError (QString msg) |
Protected Attributes | |
bool | mCacheMinMaxDirty |
QMap< int, QVariant > | mCacheMinValues |
QMap< int, QVariant > | mCacheMaxValues |
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. | |
QgsAttributeList | mAttributesToFetch |
List of attribute indices to fetch with nextFeature calls. | |
QList< NativeType > | mNativeTypes |
The names of the providers native types. | |
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QDateTime | mTimestamp |
Timestamp of data in the moment when the data were loaded by provider. |
Private Attributes | |
QMap< QString, QVariant::Type > | mOldTypeList |
old notation | |
QStringList | mErrors |
Static Private Attributes | |
static QStringList | smEncodings |
Additional Inherited Members | |
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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. | |
void | dataChanged () |
This is emitted whenever an asynchronous operation has finished and the data should be redrawn. | |
void | dataChanged (int changed) |
This is emitted whenever data or metadata (e.g. |
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 44 of file qgsvectordataprovider.h.
enumeration with capabilities that providers might implement
Definition at line 54 of file qgsvectordataprovider.h.
QgsVectorDataProvider::QgsVectorDataProvider | ( | QString | uri = QString() | ) |
Constructor of the vector provider.
uri | uniform resource locator (URI) for a dataset |
Definition at line 28 of file qgsvectordataprovider.cpp.
References setEncoding().
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Destructor.
Definition at line 38 of file qgsvectordataprovider.cpp.
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Adds new attributes.
attributes | list of new attributes |
Definition at line 83 of file qgsvectordataprovider.cpp.
Referenced by addAttributes(), QgsZonalStatistics::calculateStatistics(), and QgsVectorLayer::commitChanges().
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Add new attributes.
attributes | map of attributes name as key and type as value |
Definition at line 88 of file qgsvectordataprovider.cpp.
References addAttributes(), and nativeTypes().
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Adds a list of features.
Definition at line 73 of file qgsvectordataprovider.cpp.
Referenced by QgsVectorLayer::commitChanges().
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Return list of indexes to fetch all attributes in nextFeature()
Definition at line 255 of file qgsvectordataprovider.cpp.
References fieldCount().
Referenced by QgsVectorLayer::featureAtId(), QgsMapTip::fetchFeature(), and QgsVectorLayer::selectedFeatures().
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Definition at line 449 of file qgsvectordataprovider.cpp.
References smEncodings.
Referenced by QgsEncodingFileDialog::QgsEncodingFileDialog().
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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 138 of file qgsvectordataprovider.cpp.
References NoCapabilities.
Referenced by QgsVectorLayer::addFeature(), QgsVectorLayer::addFeatures(), capabilitiesString(), QgsVectorLayer::commitChanges(), QgsVectorLayer::deleteSelectedFeatures(), and QgsVectorLayer::startEditing().
QString QgsVectorDataProvider::capabilitiesString | ( | ) | const |
Returns the above in friendly format.
Definition at line 167 of file qgsvectordataprovider.cpp.
References AddAttributes, AddFeatures, capabilities(), ChangeAttributeValues, ChangeGeometries, CreateSpatialIndex, DeleteAttributes, DeleteFeatures, QgsDebugMsg, and SelectAtId.
Referenced by QgsVectorLayer::capabilitiesString().
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Changes attribute values of existing features.
attr_map | a map containing changed attributes |
Definition at line 113 of file qgsvectordataprovider.cpp.
Referenced by QgsZonalStatistics::calculateStatistics(), and QgsVectorLayer::commitChanges().
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Changes geometries of existing features.
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 |
Definition at line 123 of file qgsvectordataprovider.cpp.
Referenced by QgsVectorLayer::commitChanges().
void QgsVectorDataProvider::clearErrors | ( | ) |
Definition at line 503 of file qgsvectordataprovider.cpp.
References mErrors.
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Definition at line 364 of file qgsvectordataprovider.cpp.
References mCacheMinMaxDirty.
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Definition at line 439 of file qgsvectordataprovider.cpp.
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Create an attribute index on the datasource.
Definition at line 133 of file qgsvectordataprovider.cpp.
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Creates a spatial index on the datasource (if supported by the provider type).
Definition at line 128 of file qgsvectordataprovider.cpp.
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Return a short comment for the data that this provider is providing access to (e.g.
the comment for postgres table).
Definition at line 68 of file qgsvectordataprovider.cpp.
Referenced by QgsVectorLayer::dataComment().
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Returns the default value for field specified by fieldId
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Definition at line 118 of file qgsvectordataprovider.cpp.
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Deletes existing attributes.
attributes | a set containing names of attributes |
Definition at line 108 of file qgsvectordataprovider.cpp.
Referenced by QgsVectorLayer::commitChanges().
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Deletes one or more features.
id | list containing feature ids to delete |
Definition at line 78 of file qgsvectordataprovider.cpp.
Referenced by QgsVectorLayer::commitChanges().
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Returns true if the provider is strict about the type of inserted features (e.g.
no multipolygon in a polygon layer)
Definition at line 362 of file qgsvectordataprovider.h.
void QgsVectorDataProvider::enableGeometrylessFeatures | ( | bool | fetch | ) |
Set whether provider should also return features that don't have associated geometry.
false by default
Definition at line 266 of file qgsvectordataprovider.cpp.
References mFetchFeaturesWithoutGeom.
QString QgsVectorDataProvider::encoding | ( | ) | const |
Get encoding which is used for accessing data.
Definition at line 157 of file qgsvectordataprovider.cpp.
References mEncoding.
Referenced by QgsGeometryAnalyzer::buffer(), QgsGeometryAnalyzer::centroids(), QgsGeometryAnalyzer::convexHull(), QgsGeometryAnalyzer::dissolve(), QgsGeometryAnalyzer::extent(), QgsOverlayAnalyzer::intersection(), QgsGeometryAnalyzer::simplify(), and QgsVectorLayer::writeXml().
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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.
index | the index of the attribute |
enumList | reference to the list to fill |
Definition at line 218 of file qgsvectordataprovider.h.
Referenced by QgsAttributeEditor::createAttributeEditor().
QStringList QgsVectorDataProvider::errors | ( | ) |
Definition at line 513 of file qgsvectordataprovider.cpp.
References mErrors.
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Gets the feature at the given feature ID.
featureId | of the feature to be returned |
feature | which will receive the data |
fetchGeometry | flag which if true, will cause the geometry to be fetched from the provider |
fetchAttributes | a list containing the indexes of the attribute fields to copy |
Default implementation traverses all features until it finds the one with correct ID. In case the provider supports reading the feature directly, override this function.
Definition at line 52 of file qgsvectordataprovider.cpp.
References QgsFeature::id(), nextFeature(), and select().
Referenced by QgsVectorLayer::featureAtId(), QgsVectorLayer::nextFeature(), QgsVectorLayer::selectedFeatures(), QgsVectorLayer::translateFeature(), and QgsVectorLayer::undoEditCommand().
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Number of features in the layer.
Referenced by QgsZonalStatistics::calculateStatistics(), QgsVectorLayer::featureCount(), QgsVectorLayer::pendingFeatureCount(), and QgsVectorLayer::updateExtents().
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Number of attribute fields for a feature in the layer.
Referenced by attributeIndexes().
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 227 of file qgsvectordataprovider.cpp.
References fields().
Referenced by QgsZonalStatistics::calculateStatistics(), QgsUniqueValueRenderer::readXML(), and QgsContinuousColorRenderer::readXML().
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 241 of file qgsvectordataprovider.cpp.
References fields().
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Return a map of indexes with field names for this layer.
Referenced by QgsGeometryAnalyzer::buffer(), QgsGeometryAnalyzer::centroids(), QgsVectorLayer::commitChanges(), QgsVectorLayer::deleteAttribute(), QgsGeometryAnalyzer::dissolve(), QgsMapTip::fetchFeature(), fieldNameIndex(), fieldNameMap(), fillMinMaxCache(), QgsVectorLayer::hasCompatibleSymbology(), QgsOverlayAnalyzer::intersection(), maximumValue(), QgsVectorLayer::maximumValue(), minimumValue(), QgsVectorLayer::minimumValue(), QgsVectorLayer::select(), QgsVectorLayer::setDataProvider(), QgsGeometryAnalyzer::simplify(), QgsProjectFileTransform::transform0110to1000(), QgsVectorLayer::uniqueValues(), QgsVectorLayer::updateFeatureAttributes(), QgsVectorLayer::updateFieldMap(), QgsVectorLayer::writeSymbology(), QgsUniqueValueRenderer::writeXML(), and QgsContinuousColorRenderer::writeXML().
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Definition at line 369 of file qgsvectordataprovider.cpp.
References QgsFeature::attributeMap(), fields(), mCacheMaxValues, mCacheMinMaxDirty, mCacheMinValues, nextFeature(), and select().
Referenced by maximumValue(), and minimumValue().
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Get feature type.
Referenced by QgsGeometryAnalyzer::dissolve(), QgsVectorLayer::geometryType(), QgsOverlayAnalyzer::intersection(), QgsVectorLayer::setDataProvider(), and QgsGeometryAnalyzer::simplify().
bool QgsVectorDataProvider::hasErrors | ( | ) |
Definition at line 508 of file qgsvectordataprovider.cpp.
References mErrors.
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Returns the maximum value of an attribute.
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 325 of file qgsvectordataprovider.cpp.
References fields(), fillMinMaxCache(), mCacheMaxValues, and QgsDebugMsg.
Referenced by QgsVectorLayer::maximumValue().
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Returns the minimum value of an attribute.
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 309 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.
Definition at line 271 of file qgsvectordataprovider.cpp.
References mNativeTypes.
Referenced by QgsVectorLayer::addAttribute(), addAttributes(), and supportedNativeTypes().
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Get the next feature resulting from a select operation.
feature | feature which will receive data from the provider |
Referenced by QgsInterpolator::cacheBaseData(), QgsZonalStatistics::calculateStatistics(), featureAtId(), QgsMapTip::fetchFeature(), fillMinMaxCache(), and uniqueValues().
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Definition at line 518 of file qgsvectordataprovider.cpp.
References mErrors.
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Restart reading features from previous select operation.
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Select features based on a bounding rectangle.
Features can be retrieved with calls to nextFeature.
fetchAttributes | list of attributes which should be fetched |
rect | spatial filter |
fetchGeometry | true if the feature geometry should be fetched |
useIntersect | true if an accurate intersection test should be used, false if a test based on bounding box is sufficient |
Referenced by QgsInterpolator::cacheBaseData(), QgsZonalStatistics::calculateStatistics(), featureAtId(), QgsMapTip::fetchFeature(), fillMinMaxCache(), QgsVectorLayer::select(), and uniqueValues().
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Set encoding used for accessing data from layer.
Definition at line 144 of file qgsvectordataprovider.cpp.
References mEncoding, and QgsDebugMsg.
Referenced by QgsVectorDataProvider(), QgsVectorLayer::readXml(), and QgsVectorLayer::setProviderEncoding().
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Returns the permanent storage type for this layer as a friendly name.
Definition at line 42 of file qgsvectordataprovider.cpp.
Referenced by QgsVectorLayer::storageType().
const QMap< QString, QVariant::Type > & QgsVectorDataProvider::supportedNativeTypes | ( | ) | const |
Returns the names of the supported types.
Definition at line 276 of file qgsvectordataprovider.cpp.
References mOldTypeList, and nativeTypes().
bool QgsVectorDataProvider::supportedType | ( | const QgsField & | field | ) | const |
check if provider supports type of field
Definition at line 293 of file qgsvectordataprovider.cpp.
References QgsField::length(), mNativeTypes, QgsField::precision(), and QgsField::type().
Referenced by QgsVectorLayer::addAttribute().
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Return unique values of an attribute.
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 341 of file qgsvectordataprovider.cpp.
References QgsFeature::attributeMap(), nextFeature(), and select().
Referenced by QgsAttributeEditor::createAttributeEditor(), and QgsVectorLayer::uniqueValues().
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This function does nothing useful, it's kept only for compatibility.
Definition at line 47 of file qgsvectordataprovider.cpp.
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bitmask of all provider's editing capabilities
Definition at line 88 of file qgsvectordataprovider.h.
Referenced by QgsVectorLayer::startEditing().
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List of attribute indices to fetch with nextFeature calls.
Definition at line 402 of file qgsvectordataprovider.h.
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Definition at line 390 of file qgsvectordataprovider.h.
Referenced by fillMinMaxCache(), and maximumValue().
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Definition at line 389 of file qgsvectordataprovider.h.
Referenced by clearMinMaxCache(), and fillMinMaxCache().
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Definition at line 390 of file qgsvectordataprovider.h.
Referenced by fillMinMaxCache(), and minimumValue().
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Encoding.
Definition at line 393 of file qgsvectordataprovider.h.
Referenced by encoding(), and setEncoding().
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Definition at line 414 of file qgsvectordataprovider.h.
Referenced by clearErrors(), errors(), hasErrors(), and pushError().
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should provider fetch also features that don't have geometry?
Definition at line 396 of file qgsvectordataprovider.h.
Referenced by enableGeometrylessFeatures().
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True if geometry should be added to the features in nextFeature calls.
Definition at line 399 of file qgsvectordataprovider.h.
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The names of the providers native types.
Definition at line 405 of file qgsvectordataprovider.h.
Referenced by nativeTypes(), and supportedType().
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old notation
Definition at line 411 of file qgsvectordataprovider.h.
Referenced by supportedNativeTypes().
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Definition at line 417 of file qgsvectordataprovider.h.
Referenced by availableEncodings().