[Qgis-developer] Support for field aliases in expressions

[kimaidou]

Hi all,

I am not sure using alias would be easier for the users. Some thoughts :

* sometimes aliases are quite complicated, like "Contexte de l'édition" for
a field named "context". We would need to escape properly aliases in
expressions. And in this example, the real field name is much easier and
shorter thant the alias

* aliases can vary between projects or even between duplicate layers in the
same project, whereas field names are stable. If I cannot reuse some
expression for the same source table because I use different aliases, I
would spend more time to rewrite the expressions ( except if we allow to
use both in expression, but the user must then do the right choice)

* I think the problem is more that as soon as you use alias for some field,
it is then very "difficult" to find back what is the real name of the
column in the source "table" : aliases are displayed instead of the column
in every part of the Gui, which is fine but sometimes not wanted. For
example, I would love to have a button in the attribute table which let me
toggle between the aliases and the real field names as the table header.

Best wishes,
Michael

2014-09-10 19:00 GMT+02:00 Martin Dobias <wonder.sk at gmail.com>:

> Hi Mathhias
>
> On Mon, Sep 8, 2014 at 6:19 PM, Matthias Kuhn <matthias.kuhn at gmx.ch>
> wrote:
> > Hi,
> >
> > I today was discussing the idea of support for column aliases in
> > expressions. The use-case for this is that engineers using GIS in their
> > language will be able to use the same field names that they are used to
> (but
> > not in the common database which is english) to filter the attribute
> table
> > etc.
>
> I am just wondering... how the aliases would be made accessible to
> QgsExpression? Would be a map of aliases from vector layer set to each
> QgsExpression instace? Or extend QgsFields to support also aliases? Or
> something completely different? :-)
>
> Cheers
> Martin
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