[Qgis-user] Help opening a Spatialite view in QGIS

[Brent Wood]

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 <jostev at bgs.ac.uk>
Sent: Saturday, December 7, 2024 06:51
To: Brent Wood <Brent.Wood at niwa.co.nz>; 'Qgis-user at lists.osgeo.org' <qgis-user at 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-bounces at lists.osgeo.org> On Behalf Of Brent Wood via QGIS-User
Sent: 05 December 2024 21:53
To: 'Qgis-user at lists.osgeo.org' <qgis-user at 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)
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