[Qgis-developer] New feature's needed, create geometry from attribute

[HAUBOURG]

Hi all, let me precise the need:
Numerical vertex edit and wkt plugin are usefull when dealing with one geometry.
Geom calculation with field update can create eventually a WKB, but it's absolutely not user friendly, and there is actually no way to load a layer from that in a file based layer.

Think of a user getting a excel or calc spreadsheet with XY inside. The only way to import it directly as a spatial layer (not talking about using sqlite or postgis.. too complex for common users not even aware of data source types) is too export it to csv and import it with delimited text plugin.
That is always a pain since no tool exports csv in the same way when dealing with numerical / text types, decimal separators...
XLS, calc, dbf do type correctly fields and avoid any file conversion (if no formula or problem in field names today). Importing directly the datasource, and being able to spatialize it afterwards , only if needed (join pure attribute data is also a use case), would be nice.

So is the need for my corp.
My question : I would like to avoid data duplication (again) , is that feasible using pluginlayerType in python API todayu, or do I need some core modifications ? Of course, that need to be reloaded correctly with a project file.

Régis




Cordialement,
Régis Haubourg
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Régis Haubourg

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De : kimaidou [mailto:kimaidou at gmail.com]
Envoyé : dimanche 30 juin 2013 22:00
À : Anita Graser
Cc : Alexander Bruy; qgis-developer; HAUBOURG
Objet : Re: [Qgis-developer] New feature's needed, create geometry from attribute

Hi
What about using the field calculator ? I think I have seen a method in the "geometry" tools : something like geomfromwkt ? If needed, we could simply add a way to modifiy the features geometry with the field calculator, and it will do the trick.


2013/6/30 Anita Graser <anitagraser at gmx.at<mailto:anitagraser at gmx.at>>
The Quick WKT plugin does something very similar.
Anita

On Sun, Jun 30, 2013 at 3:06 PM, Alexander Bruy <alexander.bruy at gmail.com<mailto:alexander.bruy at gmail.com>> wrote:
Hi, what about NumericalVertexEdit plugin? If I understand correctly, it
do what you need.

2013/6/30 Régis Haubourg <regis.haubourg at eau-adour-garonne.fr<mailto:regis.haubourg at eau-adour-garonne.fr>>:
> Hi all,
> After some training courses here, a very common use case is not satisfied
> easily:
>
> The only entry to create geometry from text (XY or WKT) is the delimited
> text plugin.
> It appears that having a separate fonction "create point" like in Mapinfo or
> Arcgis would be really handy, and could avoid the need of csv import.
>
> I was thinking of making a plugin for this, but I'm wondering what is the
> best approach.
>  1- duplicate layer into a memory layer. Easy, requires MemoryLayerSaver to
> make data persistent, is not dynamic with datasource.
>  2- create a pluginLayer? I'm not sure it will do what I need. I would like
> the project to keep a reference to the datasource (xls, whatever ogr/
> postgres/ sqlite/ spatialite) and replace or create geometry on load by
> reading XY columns or WKT column.
>
> Is that feasable in a plugin,  as a proof of concept, or does it require
> core classes modifications (C++ work , so I won't do it by myself)
>
> Thanks for your tips,
> Régis

--
Alexander Bruy
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