In processing, if an algorithm has a boolean as an output, it cannot be defined as boolean but as a number.
To be more precise in algorithms description, the commit add QgsProcessingOutputBoolean.
populating batch processing dialog
This option adds news rows using the values from an expression
which returns an array. (As opposed to "Calculate by Expression",
which works only on existing rows).
The intended use case is to allow populating the batch dialog
using complex numeric series, e.g. those created by the "generate_series"
expression function.
For example, adding rows for a batch buffer using the expression
generate_series(100, 1000, 50)
(results in new rows with values 100, 150, 200, .... 1000)
This new option is available under the Autofill menu for a column. Selecting it allows users
to create a new QGIS expression to use to update the value inside that column. Existing
parameter values (including those from other columns) are available for use inside
the expression via @variables.
E.g. this allows setting output file names to complex expressions like
'/home/me/stuff/buffer_' || left(@input, 30) || '_' || @distance || '.shp'
to an explicit widget in the table
The double-click-header action is very hidden, and many users will
not stumble upon this. By moving it to an explicit "Autofill" widget at the
top of the table, we make this important action much more user
discoverable.
It also gives the possibility of other, parameter specific, autofill
actions (e.g. fill by expression, fill by file pattern)
And add a Processing setting to allow these to be shown. When shown, they
are highlighted in red with a tooltip explaining that the algorithm
has known issues
For algorithms with multiple parameters depending on a vector layer parameter, the code that loads the layer in the background is called repeatedly, impacting performance. A small layer cache is implemented with these changes, so the dialog only tries to load the layer once.
Instead of requiring clients to generate temporary file names themselves,
(or use the cryptic "memory:" string!), this PR adds a static constant
QgsProcessing.TEMPORARY_OUTPUT
If a layer/sink output parameter is set to QgsProcessing.TEMPORARY_OUTPUT,
then the temporary output filename will be generated automatically at
algorithm run time. This means callers don't need to mess around with
finding appropriate temporary folders and paths.
Another benefit is that TEMPORARY_OUTPUT is stored in the processing
history, so if you re-run a previous algorithm which was set to
output to a temporary file, it no longer tries to use that same
previous temporary path and instead generates a new one.
