Class: QgsAbstractCacheIndex¶
- class qgis.core.QgsAbstractCacheIndex¶
Bases:
sip.wrapper
Abstract base class for cache indices
QgsAbstractCacheIndex() Constructor for QgsAbstractCacheIndex.
QgsAbstractCacheIndex(
QgsAbstractCacheIndex
)Methods
Sometimes, the whole cache changes its state and its easier to just withdraw everything.
Is called whenever a feature is removed from the cache.
Is called when a feature request is issued on a cached layer.
Implement this method to update the the indices, in case you need information contained by the request to properly index.
- flush(self)¶
Sometimes, the whole cache changes its state and its easier to just withdraw everything. In this case, this method is issued. Be sure to clear all cache information in here.
- flushFeature(self, fid: int)¶
Is called whenever a feature is removed from the cache. You should update your indexes so they become invalid in case this feature was required to successfully answer a request.
- Parameters:
fid (int) –
- getCacheIterator(self, featureIterator: QgsFeatureIterator, featureRequest: QgsFeatureRequest) bool ¶
Is called when a feature request is issued on a cached layer.
If this cache index is able to completely answer the feature request, it will return
True
and set the iterator to a valid iterator over the cached features. If it is not able it will returnFalse
.- Parameters:
featureIterator (QgsFeatureIterator) – A reference to a
QgsFeatureIterator
. A valid featureIterator will be assigned in case this index is able to answer the request and the return value isTrue
.featureRequest (QgsFeatureRequest) – The feature request, for which this index is queried.
- Return type:
bool
- Returns:
True
, if this index holds the information to answer the request.
- requestCompleted(self, featureRequest: QgsFeatureRequest, fids: object)¶
Implement this method to update the the indices, in case you need information contained by the request to properly index. (E.g. spatial index) Does nothing by default
- Parameters:
featureRequest (QgsFeatureRequest) – The feature request that was answered
fids (object) – The feature ids that have been returned