Hi Zoltan, Since QGIS 2.6 this possibility exists. It is called "Virtual Field". You must not create the attribute when creating the shapefile. Just open the field calculator, create a new field in there and check the "virtual field" checkbox.
Regards, Matthias On 07.11.2014 16:54, Zoltan Szecsei wrote: > Hi, > I'm using QGIS 2.6.0 on Win 7 x64 - installed via OSGEO4w > > Is there a way to store your field calculator expression to always > process and update that specific field, should geometry be edited or > created for that Layer? > > Let's say I want to create a blank POINT shape file, with a text > attribute called "Sheet". > Whenever a POINT is created or moved, I want this field to be > dynamically updated with: > > tostring(abs(toint($y)))+tostring(abs(toint($x))) > > For testing thus far have: > > * created 2 points > * Opened the field calculator, clicked 'Update Existing Field' and > put in the expression. > * The two existing points now have the correct TEXT values in the > Sheet field > * I close the Field calculator > * Create a new point in my layer > * open the attribute table to find that the 'Sheet' field for this > new point is blank > * I open the Field Calculator and I cannot even find a way to call > back the previous expression I used. > > > Am I using the correct QGIS functionality to achieve what I need to, > and if so, where am I going wrong? > > Thanks & regards, > Zoltan > > > -- > > =========================================== > Zoltan Szecsei PrGISc [PGP0031] > Geograph (Pty) Ltd. > GIS and Photogrammetric Services > > P.O. Box 7, Muizenberg 7950, South Africa. > > Mobile: +27-83-6004028 > Fax: +27-86-6115323 www.geograph.co.za > =========================================== > > > _______________________________________________ > Qgis-developer mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-developer -- Help getting QGIS to the next level of quality before November 15! http://blog.vitu.ch/10102014-1046/crowdfunding-initiative-automated-testing _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
