Class: QgsAbstractCacheIndex¶
- class qgis.core.QgsAbstractCacheIndex¶
Bases:
sip.wrapper
Constructor for QgsAbstractCacheIndex.
QgsAbstractCacheIndex(
QgsAbstractCacheIndex
)Abstract base class for cache indices
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