[Qgis-developer] Spatialize attribute columns XY oor WKT, design choice

[Hugo Mercier]

Hi Régis,

Le 17/02/2014 12:08, Régis Haubourg a écrit :
> Hi, 
> Users here ask us a good reliable way to spatialize data from XY or WKT
> columns and I'm wondering what could be the reference architecture to have
> it in core. I am aware of Xytools plugins, delimited text import and
> RTQspider plugin, and also of VRT GDAL format. Questions here are for 2.3
> branch or later. 
> 
> Here are the functionnal requirements:
>  
[snip]
> VRT is IMHO no adaptated since it is not dynamic with csv data, GDAL lacks
> many options to open correctly csv (text delimiters, decimal delimiters...)
> . This is why delimited text exists. It also has no spatial index. 
> It still remains extremly powerfull for UNION, spatial queries thanks to SQL
> dialect...
> 

I think you need something very close to GDAL's VRT, but supported
natively by QGIS.

It could be (just thinking loud) something like a special
QgsVectorProvider that "wraps" another one (or many other ones) with
options like "pointsFromColumns", WKT field, etc. or with the
possibility to have "computed" columns based on QgsExpression
(geometryFromWKT already exists, we may want to add MakePoint, MakeLine,
etc.)
This provider would not allow edition of computed geometries and would
be responsible of indexes and so on.


-- 
Hugo Mercier
Oslandia