[postgis-users] Saving a split polygon

[Alexandre Neto]

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
>>
>>
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>
>
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