Just for sake of clarity, what Andreas is talking. Read the Nathan's blog about this here.
http://woostuff.wordpress.com/2011/10/27/expression-based-labeling/ Noli On 10/27/11, Andreas Neumann <[email protected]> wrote: > Hi Nathan and others, > > Thanks for developing the expression based labeling. Wow - it really > looks great. > > I have two questions and a remark: > > Question 1: the output preview of the label does not seem to work when > I use a field - is there something I need to do to enable it? I would > expect it to pull in the first record or some random record to retrieve > values? > > Question 2: how does it handle empty fields (null values)? would string > concatenation still work or do we need to coalesce() like in PostreSQL? > > Remark: > wouldn't it be cleverer to use your great new query builder and > introduce the concept of a "virtual column" in the data provider? This > way we could use your query builder for labeling, for tooltips, for read > only display in tables and forms and in the identify tool. Potentially > in the future in other scenarios as well? The query builder would then > extend the data provider and introduce a new virtual column which could > then be treated like all other columns, but read only. > > Thanks a lot for your cool work and feature enhancement towards > labeling! > > Andreas > > -- > -- > Andreas Neumann > Böschacherstrasse 10A > 8624 Grüt (Gossau ZH) > Switzerland > _______________________________________________ > Qgis-developer mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-developer > _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
