[Qgis-developer] $id not working as default value

[Tim Sutton]

Hi


> On 27 Dec 2016, at 9:40 AM, Neumann, Andreas <a.neumann at carto.net> wrote:
> 
> Hi Nyall,
> 
> Thanks for clarifying.
> 
> This needs to be properly documented and taught in QGIS courses.
> 
> 

I wonder if it is not worth floating the idea of layer annotations - something like GDAL does with it's aux.xml files that we can store stuff like this in. It is a shame to open a layer in one project where you have serial counters implemented, and then have to redo it in another project (and remember to do it). I know it would only work for file based (or maybe QGIS Layer Files too?) datasets but I recon that would cover most use cases since the 'proper' databases already have mechanisms to deal with this. Along with that we could have the layer creation dialog include a serial field type which would set up the constraints and annotate them in the layer annotation file.

Just a thought anyway...

Regards

Tim

> Andreas
> 
> On 2016-12-27 02:03, Nyall Dawson wrote:
> 
>> On 23 December 2016 at 23:37, Paolo Cavallini <cavallini at faunalia.it <mailto:cavallini at faunalia.it>> wrote:
>>> 
>>> Il 23/12/2016 14:32, Giovanni Manghi ha scritto:
>>> 
>>>> The solution from the Gitter discussion
>>>> 
>>>> aggregate( 'layername','max',"id")+1
>>> 
>>> thanks Giovanni
>>> 
>>>> We need of course a more user friendly way to allow users have
>>>> incremental/serial ids in their shapefiles...
>>> 
>>> sure, e.g. a named preset expression, as previously suggested.
>>> all the best.
>> 
>> In master you can add UNIQUE and NOT NULL constraints to the field
>> from within QGIS. This will cause QGIS to automatically populate it
>> with a serial type value whenever a new feature is created.
>> 
>> Nyall
>> 
>> 
>>> --
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—










Tim Sutton

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