Class: QgsFeatureSource¶

class qgis.core.QgsFeatureSource¶

Bases: sip.wrapper

An interface for objects which provide features via a getFeatures method.

New in version 3.0:

Methods

`allFeatureIds`	Returns a list of all feature IDs for features present in the source.
`featureCount`	Returns the number of features contained in the source, or -1 if the feature count is unknown.
`fields`	Returns the fields associated with features in the source.
`getFeatures`	Returns an iterator for the features in the source.
`hasFeatures`	Determines if there are any features available in the source.
`hasSpatialIndex`	Returns an enum value representing the presence of a valid spatial index on the source, if it can be determined.
`materialize`	Materializes a `request` (query) made against this feature source, by running it over the source and returning a new memory based vector layer containing the result.
`maximumValue`	Returns the maximum value for an attribute column or an invalid variant in case of error.
`minimumValue`	Returns the minimum value for an attribute column or an invalid variant in case of error.
`sourceCrs`	Returns the coordinate reference system for features in the source.
`sourceExtent`	Returns the extent of all geometries from the source.
`sourceName`	Returns a friendly display name for the source.
`uniqueValues`	Returns the set of unique values contained within the specified `fieldIndex` from this source.
`wkbType`	Returns the geometry type for features returned by this source.

Attributes

`FeaturesAvailable`
`FeaturesMaybeAvailable`
`NoFeaturesAvailable`
`SpatialIndexNotPresent`
`SpatialIndexPresent`
`SpatialIndexUnknown`

class FeatureAvailability¶: Bases: int

FeaturesAvailable = 1¶

FeaturesMaybeAvailable = 2¶

NoFeaturesAvailable = 0¶

SpatialIndexNotPresent = 1¶

class SpatialIndexPresence¶: Bases: int

SpatialIndexPresent = 2¶

SpatialIndexUnknown = 0¶

allFeatureIds(self) → object¶

Returns a list of all feature IDs for features present in the source.

Return type:: object

featureCount(self) → int¶

Returns the number of features contained in the source, or -1 if the feature count is unknown.

Return type:: int

fields(self) → QgsFields¶

Returns the fields associated with features in the source.

Return type:: QgsFields

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

Returns an iterator for the features in the source. An optional request can be used to optimise the returned iterator, eg by restricting the returned attributes or geometry.

Parameters:: request (QgsFeatureRequest = QgsFeatureRequest()) –
Return type:: QgsFeatureIterator

hasFeatures(self) → QgsFeatureSource.FeatureAvailability¶

Determines if there are any features available in the source.

New in version 3.2.

Return type:: QgsFeatureSource.FeatureAvailability

hasSpatialIndex(self) → QgsFeatureSource.SpatialIndexPresence¶

Returns an enum value representing the presence of a valid spatial index on the source, if it can be determined.

If QgsFeatureSource.SpatialIndexUnknown is returned then the presence of an index cannot be determined.

New in version 3.10.1.

Return type:: QgsFeatureSource.SpatialIndexPresence

materialize(self, request: QgsFeatureRequest, feedback: QgsFeedback = None) → QgsVectorLayer¶

Materializes a request (query) made against this feature source, by running it over the source and returning a new memory based vector layer containing the result. All settings from feature request will be honored.

If a subset of attributes has been set for the request, then only those selected fields will be present in the output layer.

The CRS for the output layer will match the input layer, unless QgsFeatureRequest.setDestinationCrs() has been called with a valid QgsCoordinateReferenceSystem. In this case the output layer will match the QgsFeatureRequest.destinationCrs() CRS.

The returned layer WKB type will match wkbType(), unless the QgsFeatureRequest.NoGeometry flag is set on the request. In that case the returned layer will not be a spatial layer.

An optional feedback argument can be used to cancel the materialization before it has fully completed.

The returned value is a new instance and the caller takes responsibility for its ownership.

New in version 3.0.

Parameters:

request (QgsFeatureRequest) –
feedback (QgsFeedback = None) –

Return type:

QgsVectorLayer

maximumValue(self, fieldIndex: int) → Any¶

Returns the maximum value for an attribute column or an invalid variant in case of error. The base class implementation uses a non-optimised approach of looping through all features in the source.

See also

minimumValue()

See also

uniqueValues()

Parameters:: fieldIndex (int) –
Return type:: Any

minimumValue(self, fieldIndex: int) → Any¶

Returns the minimum value for an attribute column or an invalid variant in case of error. The base class implementation uses a non-optimised approach of looping through all features in the source.

See also

maximumValue()

See also

uniqueValues()

Parameters:: fieldIndex (int) –
Return type:: Any

sourceCrs(self) → QgsCoordinateReferenceSystem¶

Returns the coordinate reference system for features in the source.

Return type:: QgsCoordinateReferenceSystem

sourceExtent(self) → QgsRectangle¶

Returns the extent of all geometries from the source. The base class implementation uses a non-optimised approach of looping through all features in the source.

Return type:: QgsRectangle

sourceName(self) → str¶

Returns a friendly display name for the source. The returned value can be an empty string.

Return type:: str

uniqueValues(self, fieldIndex: int, limit: int = -1) → Set[Any]¶

Returns the set of unique values contained within the specified fieldIndex from this source. If specified, the limit option can be used to limit the number of returned values. The base class implementation uses a non-optimised approach of looping through all features in the source.

See also

minimumValue()

See also

maximumValue()

Parameters:

fieldIndex (int) –
limit (int = -1) –

Return type:

Set[Any]

wkbType(self) → Qgis.WkbType¶

Returns the geometry type for features returned by this source.

Return type:: Qgis.WkbType