Class: QgsAbstractFeatureIteratorFromSourceQgsVectorLayerFeatureSourceBase¶
- class qgis.core.QgsAbstractFeatureIteratorFromSourceQgsVectorLayerFeatureSourceBase¶
Bases:
QgsAbstractFeatureIterator
Helper template that cares of two things: 1. automatic deletion of source if owned by iterator, 2. notification of open/closed iterator.
Note
not available in Python bindings (although present in SIP file)
Methods
Remove reference, delete if refs == 0
If you write a feature iterator for your provider, this is the method you need to implement!!
Returns a rectangle representing the original request's
QgsFeatureRequest.filterRect()
.Transforms
feature
's geometry according to the specified coordinatetransform
.to be called by from subclass in
close()
By default, the iterator will fetch all features and check if the feature matches the expression.
By default, the iterator will fetch all features and check if the id is in the request.
Setup the simplification of geometries to fetch using the specified simplify method
Add reference
Update a
QgsFeatureRequest
so that spatial filters are transformed to the source's coordinate reference system.- deref(self)¶
Remove reference, delete if refs == 0
- fetchFeature(self, f: QgsFeature) bool ¶
If you write a feature iterator for your provider, this is the method you need to implement!!
- Parameters:
f – The feature to write to
- Returns:
True
if a feature was written to f
- filterRectToSourceCrs(self, transform: QgsCoordinateTransform) QgsRectangle ¶
Returns a rectangle representing the original request’s
QgsFeatureRequest.filterRect()
. Iftransform
is a valid coordinate transform, the return rectangle will represent the requestedfilterRect()
transformed to the source’s coordinate reference system. Iterators should call this method and use the returned rectangle for filtering features to ensure that anyQgsFeatureRequest.destinationCrs()
set on the request is respected. Will throw aQgsCsException
if the rect cannot be transformed from the destination CRS.
- geometryToDestinationCrs(self, feature: QgsFeature, transform: QgsCoordinateTransform)¶
Transforms
feature
’s geometry according to the specified coordinatetransform
. Iffeature
has no geometry ortransform
is invalid then calling this method has no effect and will be shortcut. Iterators should call this method before returning features to ensure that anyQgsFeatureRequest.destinationCrs()
set on the request is respected.
- iteratorClosed(self)¶
to be called by from subclass in
close()
- nextFeatureFilterExpression(self, f: QgsFeature) bool ¶
By default, the iterator will fetch all features and check if the feature matches the expression. If you have a more sophisticated metodology (SQL request for the features…) and you check for the expression in your fetchFeature method, you can just redirect this call to fetchFeature so the default check will be omitted.
- Parameters:
f – The feature to write to
- Returns:
True
if a feature was written to f
- nextFeatureFilterFids(self, f: QgsFeature) bool ¶
By default, the iterator will fetch all features and check if the id is in the request. If you have a more sophisticated metodology (SQL request for the features…) and you are sure, that any feature you return from fetchFeature will match if the request was FilterFids you can just redirect this call to fetchFeature so the default check will be omitted.
- Parameters:
f – The feature to write to
- Returns:
True
if a feature was written to f
- prepareSimplification(self, simplifyMethod: QgsSimplifyMethod) bool ¶
Setup the simplification of geometries to fetch using the specified simplify method
- ref(self)¶
Add reference
- updateRequestToSourceCrs(self, request: QgsFeatureRequest, transform: QgsCoordinateTransform) QgsAbstractFeatureIterator.RequestToSourceCrsResult ¶
Update a
QgsFeatureRequest
so that spatial filters are transformed to the source’s coordinate reference system. Iterators should call this method against the request used for filtering features to ensure that anyQgsFeatureRequest.destinationCrs()
set on the request is respected.- Returns:
result of operation. See QgsAbstractFeatureIterator.RequestToSourceCrsResult for interpretation.
- Raises:
QgsCsException – if the rect cannot be transformed from the destination CRS.
New in version 3.22.