Class: QgsAbstractCacheIndex

class qgis.core.QgsAbstractCacheIndex

Bases: sip.wrapper

Constructor for QgsAbstractCacheIndex.

QgsAbstractCacheIndex(QgsAbstractCacheIndex)

Abstract base class for cache indices

Methods

flush Sometimes, the whole cache changes its state and its easier to just withdraw everything.
flushFeature Is called, whenever a feature is removed from the cache.
getCacheIterator Is called, when a feature request is issued on a cached layer.
requestCompleted Implement this method to update the the indices, in case you need information contained by the request to properly index.

Signals

Attributes

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.

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 return false.

Parameters:
  • featureIterator – 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 is true.
  • featureRequest – The feature request, for which this index is queried.
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 – The feature request that was answered
  • fids – The feature ids that have been returned