Class: QgsVectorDataProvider

class qgis.core.QgsVectorDataProvider(uri: str = '', providerOptions: QgsDataProvider.ProviderOptions = QgsDataProvider.ProviderOptions())

Bases: QgsDataProvider, QgsFeatureSink, QgsFeatureSource

Constructor for a vector data provider.

The uri argument specifies the uniform resource locator (URI) for the associated dataset.

Additional creation options are specified within the options value.

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.

Parameters
  • uri (str = '') –

  • providerOptions

AddAttributes = 8
AddFeatures = 1
CancelSupport = 8388608
class Capabilities

Bases: sip.wrapper

QgsVectorDataProvider.Capabilities(Union[QgsVectorDataProvider.Capabilities, QgsVectorDataProvider.Capability]) QgsVectorDataProvider.Capabilities(QgsVectorDataProvider.Capabilities)

class Capability

Bases: int

ChangeAttributeValues = 4
ChangeFeatures = 262144
ChangeGeometries = 256
CircularGeometries = 131072
CreateAttributeIndex = 4096
CreateLabeling = 33554432
CreateRenderer = 16777216
CreateSpatialIndex = 64
DeleteAttributes = 16
DeleteFeatures = 2
EditingCapabilities = 524575
FastTruncate = 1048576
class FeatureCountState

Bases: int

class NativeType(typeDesc: str, typeName: str, type: QVariant.Type, minLen: int = 0, maxLen: int = 0, minPrec: int = 0, maxPrec: int = 0, subType: QVariant.Type = QVariant.Invalid)

Bases: sip.wrapper

QgsVectorDataProvider.NativeType(QgsVectorDataProvider.NativeType)

Parameters
  • typeDesc (str) –

  • typeName (str) –

  • type (QVariant.Type) –

  • minLen (int = 0) –

  • maxLen (int = 0) –

  • minPrec (int = 0) –

  • maxPrec (int = 0) –

  • subType (QVariant.Type = QVariant.Invalid) –

mMaxLen
mMaxPrec
mMinLen
mMinPrec
mSubType
mType
mTypeDesc
mTypeName
NoCapabilities = 0
ReadLayerMetadata = 2097152
RenameAttributes = 524288
SelectAtId = 128
SelectEncoding = 8192
SimplifyGeometries = 16384
SimplifyGeometriesWithTopologicalValidation = 32768
TransactionSupport = 65536
Uncounted = -2
UnknownCount = -1
WriteLayerMetadata = 4194304
addAttributes(self, attributes: object) → bool

Adds new attributes to the provider. Returns True in case of success and False in case of failure. If attributes are added using this method then QgsVectorLayer.updateFields() must be called manually to ensure that the layer’s field are correctly reported.

Parameters

attributes (object) –

Return type

bool

addFeatures(self, flist: Iterable[QgsFeature], flags: Union[QgsFeatureSink.Flags, QgsFeatureSink.Flag] = 0) → Tuple[bool, List[QgsFeature]]
Parameters
Return type

Tuple[bool, List[QgsFeature]]

aggregate(self, aggregate: QgsAggregateCalculator.Aggregate, index: int, parameters: QgsAggregateCalculator.AggregateParameters, context: QgsExpressionContext, fids: object = None) → Tuple[Any, bool]

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.

Parameters
  • aggregate (QgsAggregateCalculator.Aggregate) – aggregate to calculate

  • index (int) – the index of the attribute to calculate aggregate over

  • parameters (QgsAggregateCalculator.AggregateParameters) – parameters controlling aggregate calculation

  • context (QgsExpressionContext) – expression context for filter

  • ok – will be set to True if calculation was successfully performed by the data provider

  • fids (object = None) – list of fids to filter, otherwise will use all fids

Return type

Tuple[Any, bool]

Returns

calculated aggregate value

New in version 2.16.

appendError()
attributeIndexes(self) → List[int]

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

Return type

List[int]

availableEncodings() → List[str]

Returns a list of available encodings

Return type

List[str]

cancelReload(self) → bool

Cancels the current reloading of data.

Return type

bool

Returns

True if the reloading has been correctly interrupted, False otherwise

See also

reloadData()

New in version 3.2.

capabilities(self) → QgsVectorDataProvider.Capabilities

Returns flags 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.

Return type

QgsVectorDataProvider.Capabilities

capabilitiesString(self) → str

Returns the above in friendly format.

Return type

str

changeAttributeValues(self, attr_map: object) → bool

Changes attribute values of existing features. This should succeed if the provider reports the ChangeAttributeValues capability.

Parameters

attr_map (object) – a map containing changed attributes

Return type

bool

Returns

True in case of success and False in case of failure

changeFeatures(self, attr_map: object, geometry_map: object) → bool

Changes attribute values and geometries of existing features. This should succeed if the provider reports both the ChangeAttributeValues and ChangeGeometries capabilities. Providers which report the ChangeFeatures capability implement an optimised version of this method.

Parameters
  • attr_map (object) – a map containing changed attributes

  • geometry_map (object) – A QgsGeometryMap whose index contains the feature IDs that will have their geometries changed. The second map parameter being the new geometries themselves

Return type

bool

Returns

True in case of success and False in case of failure

changeGeometryValues(self, geometry_map: object) → bool

Changes geometries of existing features

Parameters

geometry_map (object) – A QgsGeometryMap whose index contains the feature IDs that will have their geometries changed. The second map parameter being the new geometries themselves

Return type

bool

Returns

True in case of success and False in case of failure

childEvent()
clearErrors(self)

Clear recorded errors

clearMinMaxCache(self)

Invalidates the min/max cache. This will force the provider to recalculate the cache the next time it is requested.

connectNotify()
convertToProviderType(self, geom: QgsGeometry) → QgsGeometry

Converts the geometry to the provider type if possible / necessary

Return type

QgsGeometry

Returns

the converted geometry or None if no conversion was necessary or possible

Parameters

geom (QgsGeometry) –

convertValue(type: QVariant.Type, value: str) → Any
Parameters
  • type (QVariant.Type) –

  • value (str) –

Return type

Any

createAttributeIndex(self, field: int) → bool

Create an attribute index on the datasource

Parameters

field (int) –

Return type

bool

createLabeling(self, configuration: Dict[str, Any] = {}) → QgsAbstractVectorLayerLabeling

Creates labeling settings, using provider backend specific information.

The configuration map can be used to pass provider-specific configuration maps to the provider to allow customization of the returned labeling object. Support and format of configuration varies by provider.

When called with an empty configuration map the provider’s default labeling settings will be returned.

This method returns a new labeling settings and the caller takes ownership of the returned object.

Only providers which report the CreateLabeling capability will return labeling settings. Other providers will return None.

New in version 3.6.

Parameters

configuration (Dict[str) –

Return type

QgsAbstractVectorLayerLabeling

createRenderer(self, configuration: Dict[str, Any] = {}) → QgsFeatureRenderer

Creates a new vector layer feature renderer, using provider backend specific information.

The configuration map can be used to pass provider-specific configuration maps to the provider to allow customization of the returned renderer. Support and format of configuration varies by provider.

When called with an empty configuration map the provider’s default renderer will be returned.

This method returns a new renderer and the caller takes ownership of the returned object.

Only providers which report the CreateRenderer capability will return a feature renderer. Other providers will return None.

New in version 3.2.

Parameters

configuration (Dict[str) –

Return type

QgsFeatureRenderer

createSpatialIndex(self) → bool

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

Return type

bool

Returns

True in case of success

customEvent()
dataComment(self) → str

Returns a short comment for the data that this provider is providing access to (e.g. the comment for postgres table).

Return type

str

defaultValue(self, fieldIndex: int) → Any

Returns any literal default values which are present at the provider for a specified field index. Important - this should ONLY be called when creating an attribute to insert directly into the database. Do not call this method for non-feature creation or modification, e.g., when validating an attribute or to compare it against an existing value, as calling it can cause changes to the underlying data source (e.g., Postgres provider where the default value is calculated as a result of a sequence). It is recommended that you instead use the methods in QgsVectorLayerUtils such as QgsVectorLayerUtils.createFeature() so that default value handling and validation is automatically carried out.

Parameters

fieldIndex (int) –

Return type

Any

defaultValueClause(self, fieldIndex: int) → str

Returns any default value clauses which are present at the provider for a specified field index. These clauses are usually SQL fragments which must be evaluated by the provider, e.g., sequence values.

See also

defaultValue()

New in version 3.0.

Parameters

fieldIndex (int) –

Return type

str

deleteAttributes(self, attributes: object) → bool

Deletes existing attributes from the provider. If attributes are deleted using this method then QgsVectorLayer.updateFields() must be called manually to ensure that the layer’s field are correctly reported.

Parameters

attributes (object) – a set containing indices of attributes

Return type

bool

Returns

True in case of success and False in case of failure

deleteFeatures(self, id: object) → bool

Deletes one or more features from the provider. This requires the DeleteFeatures capability.

Parameters

id (object) – list containing feature ids to delete

Return type

bool

Returns

True in case of success and False in case of failure

See also

truncate()

dependencies(self) → Set[QgsMapLayerDependency]

Gets the list of layer ids on which this layer depends. This in particular determines the order of layer loading.

Return type

Set[QgsMapLayerDependency]

disconnectNotify()
discoverRelations(self, self: QgsVectorLayer, layers: Iterable[QgsVectorLayer]) → List[QgsRelation]

Discover the available relations with the given layers.

Parameters
Return type

List[QgsRelation]

Returns

the list of N-1 relations from this provider.

New in version 3.0.

doesStrictFeatureTypeCheck(self) → bool

Returns True if the provider is strict about the type of inserted features (e.g. no multipolygon in a polygon layer)

Return type

bool

empty(self) → bool

Returns True if the layer does not contain any feature.

New in version 3.4.

Return type

bool

encoding(self) → str

Gets encoding which is used for accessing data

Return type

str

enumValues(self, index: int) → List[str]

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 (int) – the index of the attribute

Return type

List[str]

errors(self) → List[str]

Gets recorded errors

Return type

List[str]

featureCount(self) → int

Number of features in the layer

Return type

int

Returns

long containing number of features

featureSource(self) → QgsAbstractFeatureSource

Returns 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.

Return type

QgsAbstractFeatureSource

Returns

new instance of QgsAbstractFeatureSource (caller is responsible for deleting it)

New in version 2.4.

fieldConstraints(self, fieldIndex: int) → QgsFieldConstraints.Constraints

Returns any constraints which are present at the provider for a specified field index.

New in version 3.0.

Parameters

fieldIndex (int) –

Return type

QgsFieldConstraints.Constraints

fieldNameIndex(self, fieldName: str) → int

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

Parameters

fieldName (str) –

Return type

int

fieldNameMap(self) → object

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

Return type

object

fields(self) → QgsFields

Returns the fields associated with this data provider.

Return type

QgsFields

fillMinMaxCache(self)

Populates the cache of minimum and maximum attribute values.

forceReload(self)

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.

getFeatures(self, request: QgsFeatureRequest = QgsFeatureRequest()) → QgsFeatureIterator

Query the provider for features specified in request.

Parameters

request (QgsFeatureRequest = QgsFeatureRequest()) – feature request describing parameters of features to return

Return type

QgsFeatureIterator

Returns

iterator for matching features from provider

handlePostCloneOperations(self, source: QgsVectorDataProvider)

Handles any post-clone operations required after this vector data provider was cloned from the source provider.

New in version 3.8.1.

Parameters

source (QgsVectorDataProvider) –

hasErrors(self) → bool

Provider has errors to report

Return type

bool

hasFeatures(self) → QgsFeatureSource.FeatureAvailability

Will always return FeatureAvailability.FeaturesAvailable or FeatureAvailability.NoFeaturesAvailable.

Calls empty() internally. Providers should override empty() instead if they provide an optimized version of this call.

See also

empty()

New in version 3.4.

Return type

QgsFeatureSource.FeatureAvailability

hasMetadata(self) → bool

Returns True if the data source has metadata, False otherwise.

Return type

bool

Returns

True if data source has metadata, False otherwise.

New in version 3.0.

isDeleteStyleFromDatabaseSupported(self) → bool

It returns False by default. Must be implemented by providers that support delete styles from db returning True

Return type

bool

isSaveAndLoadStyleToDatabaseSupported(self) → bool

It returns False by default. Must be implemented by providers that support saving and loading styles to db returning True

Return type

bool

isSignalConnected()
maximumValue(self, index: int) → Any

Returns the maximum value of an attribute

Parameters

index (int) – 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.

Return type

Any

metadata(self) → Dict[str, Any]

Gets metadata, dependent on the provider type, that will be display in the metadata tab of the layer properties.

Return type

Dict[str, Any]

Returns

The provider metadata

minimumValue(self, index: int) → Any

Returns the minimum value of an attribute

Parameters

index (int) – 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.

Return type

Any

nativeTypes(self) → List[QgsVectorDataProvider.NativeType]

Returns the names of the supported types

Return type

List[QgsVectorDataProvider.NativeType]

palAttributeIndexNames(self) → Dict[int, str]

Returns list of indexes to names for QgsPalLabeling fix

Return type

Dict[int, str]

pkAttributeIndexes(self) → List[int]

Returns list of indexes of fields that make up the primary key

Return type

List[int]

pushError(self, msg: str)

Push a notification about errors that happened in this providers scope. Errors should be translated strings that require the users immediate attention.

For general debug information use QgsMessageLog.logMessage() instead.

New in version 3.0.

Parameters

msg (str) –

raiseError

Signals an error in this provider

New in version 3.0: [signal]

Parameters

msg (str) –

receivers()
renameAttributes(self, renamedAttributes: Dict[int, str]) → bool

Renames existing attributes. If attributes are renamed using this method then QgsVectorLayer.updateFields() must be called manually to ensure that the layer’s field are correctly reported.

Parameters

renamedAttributes (Dict[int) – map of attribute index to new attribute name

Return type

bool

Returns

True in case of success and False in case of failure

New in version 2.16.

sender()
senderSignalIndex()
setEncoding(self, e: str)

Set encoding used for accessing data from layer

Parameters

e (str) –

setError()
setNativeTypes(self, nativeTypes: Iterable[QgsVectorDataProvider.NativeType])

Set the list of native types supported by this provider. Usually done in the constructor.

New in version 3.0.

Parameters

nativeTypes (Iterable[QgsVectorDataProvider.NativeType]) –

skipConstraintCheck(self, fieldIndex: int, constraint: QgsFieldConstraints.Constraint, value: Any = None) → bool

Returns True if a constraint check should be skipped for a specified field (e.g., if the value returned by defaultValue() is trusted implicitly. An optional attribute value can be passed which can help refine the skip constraint check.

New in version 3.0.

Parameters
Return type

bool

sourceCrs(self) → QgsCoordinateReferenceSystem
Return type

QgsCoordinateReferenceSystem

sourceExtent(self) → QgsRectangle
Return type

QgsRectangle

sourceName(self) → str
Return type

str

storageType(self) → str

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

Return type

str

supportedType(self, field: QgsField) → bool

check if provider supports type of field

Parameters

field (QgsField) –

Return type

bool

textEncoding(self) → QTextCodec

Gets this providers encoding

New in version 3.0.

Return type

QTextCodec

timerEvent()
transaction(self) → QgsTransaction

Returns the transaction this data provider is included in, if any.

Return type

QgsTransaction

translateMetadataKey(self, mdKey: str) → str

Gets the translated metadata key.

Parameters

mdKey (str) – The metadata key

Return type

str

Returns

The translated metadata value

translateMetadataValue(self, mdKey: str, value: Any) → str

Gets the translated metadata value.

Parameters
  • mdKey (str) – The metadata key

  • value (Any) – The metadata value

Return type

str

Returns

The translated metadata value

truncate(self) → bool

Removes all features from the layer. This requires either the FastTruncate or DeleteFeatures capability. Providers with the FastTruncate capability will use an optimised method to truncate the layer.

Return type

bool

Returns

True in case of success and False in case of failure.

See also

deleteFeatures()

New in version 3.0.

uniqueStringsMatching(self, index: int, substring: str, limit: int = -1, feedback: QgsFeedback = None) → List[str]

Returns unique string values of an attribute which contain a specified subset string. Subset matching is done in a case-insensitive manner.

Parameters
  • index (int) – the index of the attribute

  • substring (str) – substring to match (case insensitive)

  • limit (int = -1) – maxmum number of the values to return, or -1 to return all unique values

  • feedback (QgsFeedback = None) – optional feedback object for canceling request

Return type

List[str]

Returns

list of unique strings containing substring

wkbType(self) → QgsWkbTypes.Type

Returns the geometry type which is returned by this layer

Return type

QgsWkbTypes.Type