On Fri, Jun 20, 2014 at 1:00 PM, Nyall Dawson <nyall.daw...@gmail.com> wrote: > On 20 June 2014 15:43, Martin Dobias <wonder...@gmail.com> wrote: > >> >> Actually the dot syntax would imply on the fly evaluation. When >> parsing, it is not possible to decide what will be the content of an >> object. >> >> This would be similar to python: the expression x.y means that in >> object x it should look up "x" in the dictionary of attributes and >> return its value. > > I mean column names which are themselves the result of an evaluated > expression. For eaxmple, if my table was something like: > > id, label_with, label1, label2 > 1000, 1, 'a', 'b' > 1001, 2, 'a', 'b' > > I'd like to be able to label this with an expression like: attribute( > feature, 'label' || "label_with"). If the column name was evaluated as > a result of the 'label' || "label_with" expression, then the returned > feature attribute value would be 'a' for feature 1000 and 'b' for > feature 1001. (Sorry for the confusing example!). Could this be done > using dot notation?
No, with dot notation you would need to use a proper field name (could be enclosed in double quotes though) The "attribute" method could co-exist for these advanced cases - like in Python there is the buildin function getattr(object, name[, default]) for the same purpose. Regards Martin _______________________________________________ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
