[Qgis-developer] Expression based labeling

[Andreas Neumann]

 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

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 Andreas Neumann
 Böschacherstrasse 10A
 8624 Grüt (Gossau ZH)
 Switzerland