307aabd66a
This commit adds a number of different forms of aggregates to
the expression engine.
1. Aggregates within the current layer, eg sum("passengers")
Supports sub expressions (ie sum("passengers"/2) ), group by
( sum("passengers", group_by:="line_segment") ), and optional
filters ( sum("passengers", filter:= "station_class" > 3 ) )
2. Relational aggregates, which calculate an aggregate over
all matching child features from a relation, eg
relation_aggregate( 'my_relation', 'mean', "some_child_field" )
3. A summary aggregate function, for calculating aggregates
on other layers. Eg aggregate('rail_station_layer','sum',"passengers")
The summary aggregate function supports an optional filter,
making it possible to calculate things like:
aggregate('rail_stations','sum',"passengers",
intersects(@atlas_geometry, $geometry ) )
for calculating the total number of passengers for the stations
inside the current atlas feature
In all cases the calculations are cached inside the expression
context, so they only need to be calculated once for each
set of expression evaluations.
Sponsored by Kanton of Zug, Switzerland
QGIS unit tests
Build tests
Make sure that you have enabled building of tests in CMake.
cmake -DENABLE_TESTS=ON ..
Run tests
You can run all tests using make check.
Individual tests can be run using ctest.
For example if the output of make check ends like this:
The following tests FAILED:
77 - PyQgsLocalServer (Failed)
You could re-run the failing test with:
ctest -V -R PyQgsLocalServer
The parameter -V enables verbose mode and -R takes a regular expression as
parameter and will only run matching tests.
Advanced configuration
Postgres
Make sure that you have enabled building of postgres test in CMake.
cmake -DENABLE_PGTEST=ON ..
To test the postgres provider you will need to have a database available to which the postgres provider can connect. The server will need to have postgis support enabled.
By default the test uses the following connection string:
dbname=qgis_test
If this does not match your setup you can set the environment variable
QGIS_PGTEST_DB to the desired connection string, or you can rely
on standard libpq environment variables to tweak host, port user and
password (PGHOST, PGPORT, PGUSER, PGPASSWORD).
Please note that the database needs to be initialized using the sql-scripts:
tests/testdata/provider/testdata_pg*.sql
They take care of activating postgis for the test database and create some tables containing test data.
For convenience, a shell script is provided to create the database and initialize it as needed:
tests/testdata/provider/testdata_pg.sh