Figured it out:
The field names of a vector field input ("groupingfields") are stored as
an array. As I wanted to combine the values of those fields, I first had
to extract the fieldname from this array (e.g.
array_get(@groupingfields,0)), and then get the attribute for each
feature for this field attribute( array_get(@groupingfields,0))|
Doing the same for the second field and pasting them together gives my
new identifier field for my polygons in the field calculator:
attribute( array_get(@groupingfields,0))||'_'|| attribute(
array_get(@groupingfields ,1))
Nice! Automation of atlas and afterwards world domination are at hand.
On 13.09.20 14:00, Bernd Vogelgesang wrote:
Hi there,
I am trying to use the "Vector Field" input with more than one field
in a model for generating atlas zones:
To create individual oriented bounding boxes over polygon sketches, I
need to create an individual attribute for each polygon. The problem
is that the individual distinction of a polygon is defined through at
least two fields (lets call them "location" and "zone")
As the zone names get repeated over the different locations, only the
combination of location and zone will identify the individual plot.
In the vector field input, there is the possibility to mark multiple
fields from a vector layer as input.
My idea was now, to create a new field "combi" from the marked fields
and use it to create my oriented boxes.
The question is now, how the value in the multi-field input is stored
and how I can extract the individual parts for usage in the field
calculator.
Given my vector field input is names "groupingfields", I can access it
in the field calculator as @groupingfields.
But how can I extract the values, so that in pseudocode the "combi"
field expression will look like '@groupingfield[1] || '_' ||
@groupingfield[2] (which of course does not work, thats why I'm asking) ?
I case the question arises, why I do not simply create that
combi-field beforehand for my polygons outside of the model: Simply, I
do not want to. I want to be the master of my data, and not its slave ;)
Thanx for any input,
Bernd
_______________________________________________
Qgis-user mailing list
[email protected]
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
