[postgis-users] Saving a split polygon

[Peter Brown]

uummmm
Reading your answer {particularly the bit about  a
nextval('yourtable_gid_seq'::regclass),} I realise that this bit of code is
an area of knowledge that I am missing, and clearly if it will solve my
problem then it would be useful. I wonder if I could ask you to at least
point me in the right direction.
I am fairly new to QGIS but generally a power user of databases, so I have
read the excellent manual
http://workshops.opengeo.org/postgis-intro/creating_db.html
and the more fundamental one at
http://www.postgresql.org/docs/9.2/interactive/sql.html
However, I do not seem to have come across anything like this. Can you
advise me?
Thank you for your help
Regards
Peter Brown


On 7 October 2013 11:09, Alexandre Neto <senhor.neto at gmail.com> wrote:

> Hello,
>
> I'm not sure If I followed your question, but in my experience with QGIS
> editing Postgres\postgis spatial tables, I add some smal hickups, but never
> with splitting.
>
> If its a normal polygon and you wish to split it with a line, QGIS will
> assign to all your new polygons a nextval('yourtable_gid_seq'::regclass),
> and this should solve the PK's problem.
>
> If it's a multipart polygon that you want to spit it's parts, you can use
> the multipartsplit plugin, and it will also take care of your primary keys.
>
> Maybe it's a problem with your table, please send the creation SQL command
> and maybe someone can have a clue of what is happening.
>
>
>
> On Mon, Oct 7, 2013 at 10:41 AM, Peter Brown <peterbrown.kew at gmail.com>wrote:
>
>> Thanks for your prompt response, it is nice to know that it is possible,
>> but the methods you remember do seem to have problems.
>> - in QGIS I can split a polygon which is on a layer, and under the
>> 'layer' option on the menu, I call up the attributes table, but that only
>> offers me all the fields in the base PostGIS table EXCEPT   (a) the  ID and
>> (b) the geometry
>> - I have tried manufacturing another PostGIS table with all the
>> attributes of the polygon except an ID field with all its 'NO NULLS' etc,
>> but then when I open a layer in QGIS it draws the polygon but shows it as
>> not editable
>> You have obviously managed something clever, but I am not quite sure what
>> Regards
>> Peter Brown
>>
>>
>> On 7 October 2013 09:32, Hugues François <hugues.francois at irstea.fr>wrote:
>>
>>> **
>>> Hello,
>>>
>>> I previously edited polygons from postgis within qgis and with no
>>> problem. If I remember well, before saving I also filled attribute data to
>>> give a new ID. Maybe if you just want to edit polygons without changing
>>> attributes, you may remove constraints on your postgis table (especially,
>>> uniques, not null and primary key) before editing (and then put the things
>>> right back to postgis).
>>>
>>> Hugues.
>>>
>>>
>>>
>>>  ------------------------------
>>> *From:* postgis-users-bounces at lists.osgeo.org [mailto:
>>> postgis-users-bounces at lists.osgeo.org] *On Behalf Of *Peter Brown
>>> *Sent:* Monday, October 07, 2013 9:53 AM
>>> *To:* postgis-users at lists.osgeo.org
>>> *Subject:* [postgis-users] Saving a split polygon
>>>
>>>  In Quantum GIS (QGIS) there is a very useful facility for taking a
>>> polygon in a PostGIS database linked to QGIS and splitting it. HOWEVER,
>>> when one then tries to save the two portions, PostGIS puts up an error
>>> message that it cannot save the new portion because it does not have a new
>>> ID (it can save the existing portion, because this is only an edit of an
>>> existing ID).
>>> There are workarounds for this (e.g. convert to 'Shape' files) but they
>>> seem incredibly clumsy. Does anyone have a more direct solution?
>>> Thanks
>>> Peter Brown
>>>
>>>
>>> _______________________________________________
>>> postgis-users mailing list
>>> postgis-users at lists.osgeo.org
>>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
>>>
>>
>>
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