[Qgis-developer] Expression based labeling

[Noli Sicad]

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 <a.neumann at carto.net> 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
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