On Tue, 11 Aug 2020 at 18:48, Andreas Neumann <a.neum...@carto.net> wrote: > > Hi Ujaval, > > Thanks for the "hacky" idea ;-) > > I am happy to report that it worked for me. > > For the long run, it would be good to have an algorithm to extract a string > from an attribute of a selected feature (something like > attribute(get_feature(expression_to_get_feature),attribute) ) or at least an > "Expression Executor" that outputs a string. Expressions can do a lot, but > getting a string output from an Expression seems to be impossible.
This is true -- a number of expressions which work fine in QGIS itself fail in the modeler. Specifically, any which reference layers directly which have been created as a result of previous steps in the model won't work (aggregates, get_feature, etc). Would be good to resolve this at some stage, but it's not a 5 minute fix (closer to 0.5-1 day). Given this, I think a simple "get attribute for first feature" algorithm for use in models could be useful... Nyall > > Anyway, I can progress now with the rest of my model. > > Thanks again, > > Andreas > > On 2020-08-11 10:15, Ujaval Gandhi wrote: > > I can think of a slightly hacky way. Use the 'Basic Statistics for Field' > algorithm, and since your field will have a single value, use either the > Minimum or Maximum value output from it (works for string fields too) as the > parameter for another algorithm. > > Ujaval Gandhi > Spatial Thoughts > mobile: +91-8095684687 > email: uja...@spatialthoughts.com > > Subscribe to our newsletter http://bit.ly/spatialthoughts-newsletter > > On Tue, Aug 11, 2020 at 1:23 PM Andreas Neumann <a.neum...@carto.net> wrote: > > Hi, > > In a model I aggregate values to a single feature. Then I would like to > extract a specific aggregated attribute to a string so I can use it as the > input parameter of another algorithm. > > I fail to find a way to do that. Aggregation works fine, string concatenation > as well, but I fail to find a way to extract an attribute of a single feature > to a string. > > Any ideas? > > I'm on QGIS 3.10, but if necessary I could also use a newer QGIS version. > > Thanks, > > Andreas > > _______________________________________________ > QGIS-Developer mailing list > QGIS-Developer@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer > > > _______________________________________________ > QGIS-Developer mailing list > QGIS-Developer@lists.osgeo.org > List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer _______________________________________________ QGIS-Developer mailing list QGIS-Developer@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
