Hi John,
Thanks for getting back to me.
The following commands are used to create the view (from a bash script), they
include creating the unique index on station_no. QGIS is still unable to load
the layer, despite listing it as a spatial table in the database.
I have not tried using the station_no column as a primary key, which may make a
difference, though it shouldn't.
DB=tan2413.spdb
# create unique constraint on station_no
echo "drop index uniq_stn;" | spatialite $DB
echo "create unique index uniq_stn on station(station_no);" | spatialite $DB
# remove existing view & metadata before creating
echo "drop view v_stat;" | spatialite $DB
echo "delete from views_geometry_columns where view_name = 'v_stat';" |
spatialite $DB
# create view and register
echo "create view v_stat as select station_no, startp from station;" |
spatialite $DB
echo "insert into views_geometry_columns
(view_name, view_geometry, view_rowid, f_table_name, f_geometry_column,
read_only)
values
('v_stat', 'startp', 'station_no', 'station', 'startp', 1);" |
spatialite $DB
So I still can't add a view in QGIS.
Brent Wood
Principal Technician, Fisheries
NIWA
DDI: +64 (4) 3860529
________________________________
From: John Stevenson - BGS <jos...@bgs.ac.uk>
Sent: Saturday, December 7, 2024 06:51
To: Brent Wood <brent.w...@niwa.co.nz>; 'Qgis-user@lists.osgeo.org'
<qgis-user@lists.osgeo.org>
Subject: RE: Help opening a Spatialite view in QGIS
Hi Brent,
I’ve often found that the problem with views has come from the id column. Does
the integer “station_no” column have a unique constraint? It may need one.
I put some notes on Spatialite views in this Stack Exchange answer a few years
ago.
https://gis.stackexchange.com/a/301444/64762
John
From: QGIS-User <qgis-user-boun...@lists.osgeo.org> On Behalf Of Brent Wood via
QGIS-User
Sent: 05 December 2024 21:53
To: 'Qgis-user@lists.osgeo.org' <qgis-user@lists.osgeo.org>
Subject: [Qgis-user] Help opening a Spatialite view in QGIS
Hi,
I have created a view in a spatialite database, but am unable to open it in
QGIS.
I can't find any documentation on how this works.
I have a table "stations" which contains a station_no column (integer) and a
point geometry column (startp, EPSG 4326).
The view is created by:
create view v_stat as select station_no, startp from station;
I add an entry to the Spatialite views_geometry_columns table to populate the
metadata describing the view.
insert into views_geometry_columns
(view_name, view_geometry, view_rowid, f_table_name, f_geometry_column,
read_only)
values
('v_stat', 'startp', 'station_no', 'station', 'startp', 1)
QGIS now lists the view correctly as a table with a geometry & lists startp as
the geometry, but when I try to open it, I just get an "invalid layer" error
message.
dbname='/home/baw/tan2413/tan2413.spdb' table="v_stat" (startp) is an invalid
layer - not loaded
Can anyone tell me how to set up a Spatialite view so it can be successfully
opened in QGIS?
Thanks
Brent Wood
Principal Technician, Fisheries
NIWA
DDI: +64 (4) 3860529
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Brent Wood
Principal Technician - GIS and Spatial Data Management
Programme Leader - Environmental Information Delivery
+64-4-386-0529
National Institute of Water & Atmospheric Research Ltd (NIWA)
301 Evans Bay Parade Hataitai Wellington New Zealand
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