[Qgis-user] How to create easily and fast an empty GRASS vector-layer to use it in Quantum GIS?

[Craig Leat]

Hi Philipp

Please see my comments below.

Philipp Steigenberger wrote:

> Date: Tue, 26 Feb 2008 16:56:59 +0100
> From: Philipp Steigenberger <userlist at online.de>
> Subject: [Qgis-user] How to create easily and fast an empty
> 	vector-layer to use it in Quantum GIS?
> To: qgis-user at lists.osgeo.org
> Message-ID: <47C436CB.3030505 at online.de>
> Content-Type: text/plain; charset=ISO-8859-15; format=flowed
>
> Hi there,
> I posted this on the grassuser-list before, but couldnt get support...
>
> I recovered QGIS as an alternative offer to the v.digit (GRASS) tool and 
> played  a little with it last week. While I can create a new vector map 
> using the -n flag in v.digit and creating a new table in the 
> settings-window, I couldn't find a similar option in QGIS.
> Is there any?
>   

In version 0.9.1 I have a menu option "Create new GRASS Vector", but for 
me it always crashes QGIS. I have also found that QGIS will not open an 
empty GRASS vector, so I always start with v.digit -n someMap and draw 
something before switching over to QGIS.

> -> How to create a new GRASS-Vectorlayer within QGIS and link it to a 
> database (dbf) table.
>
> Therefore I tried to create an empty vectormap in GRASS using
>
>  >v.edit tmp  tool=create
>  >v.db.addtable tmp
>  >v.db.addcol tmp col="number DOUBLE"
>
> After that I started QGIS and tried to open the map but I got the message:
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  >>THE LAYER IS NOT A VALID LAYER AND CANNOT BE ADDED TO THE MAP
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
> same when I use
>
>  >v.edit tmp  tool=create
> Yv.db.addtable tmp
>
> or just
>
>  >v.edit tmp  tool=create
>
> Whats wrong?
> How to create an empty vektorlayer in GRASS whitch is usable in QGIS?
>
> Sometimes when I try to open other maps QGIS exits and I get the messeage:
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  >>error_routine (fatal = 1): Unable to open vector map <p_mund at 2> on 
> topology level 2
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   

QGIS (and GRASS) are unable to open a GRASS vector if topology hasn't 
been built and topology only gets built on a clean exit from the 
digitizer. To close the GRASS Edit window you must use the red close 
button on the toolbar. If you click the upper right cross to close the 
window topology will not be built. Well that's my experience at least 
with my system. To fix broken topology run v.build someMap from within 
GRASS.

Best regards

Craig

> thanks for helping
> cheers
> Philipp
>
> QGIS 0.7.4
> GRASS 6,3 svn
> debian etch
>