If os.path.isfile(sqlite_cache_file) is False, the Attribute cache_connection was not assigned and so an Attribute Error occured in the following lines.
This is the implementation of the new DB connections API (grant proposal 2019).
Summary
The new API makes it available to QGIS core a new interface for provider connections and will allow to:
replace the provider specific QgsSettings management in QGIS4 (save/load connections from the settings) NOT IN SCOPE FOR NOW.
provide a unified API for common operations on DB connections:
executeSql and get the results
list tables names and properties and schemas
create a new vector table (no rasters for now)
create/rename/drop schemas and tables
vacuum
....
The "comments" PR 8831 added support for postgres only
(and broke all the others backends).
I'd be in favor of a revert of the whole original PR but
this patch restores functionality and could be an acceptable
temporary fix until the comments PR is reworked in a more
maintainable and elegant way.
Fixes#21151 btw
Since the majority of users of this class will be exporting
an existing map layer to a data provider, the QgsVectorLayerImport
name is misleading and suggests that this class is designed
just to bring layers "into" QGIS.
Explicitly naming the class "Exporter" should help API users
discover this class.
Also cleanup API and improve docs
* Remove deprecated Qgis::WKBType and API cleanup
Renames QgsWKBTypes to QgsWkbTypes
Replaces usage of the enums:
* Qgis::WKBType with QgsWkbTypes::Type
* Qgis::GeometryType with QgsWkbTypes::GeometryType
Their values should be forward compatible (a fact that was already
explited up to now by casting between the types)
Renames some SSLxxx to SslXxx and URIxxx to UriXxx
* Fix build warnings and simplify type handling
* Add a fixer to rewrite imports
* The forgotten rebase conflictThe forgotten rebase conflicts
* QgsDataSourcURI > QgsDataSourceUri
* QgsWKBTypes > QgsWkbTypes
* Qgis.WKBGeom > QgsWkbTypes.Geom
* Further python fixes
* Guess what... Qgis::wkbDimensions != QgsWkbTypes::wkbDimensions
* Fix tests
* Python 3 updates
* [travis] pull request caching cannot be disabled
so at least use it in r/w mode
* Fix python3 print in plugins
