[Qgis-developer] Stationary objects that change attribute values over time

[Anita Graser]

On Thu, Feb 23, 2017 at 5:54 PM, Anita Graser <anitagraser at gmx.at> wrote:

> On Sat, Feb 18, 2017 at 8:41 PM, Anita Graser <anitagraser at gmx.at> wrote:
>
>> Hi,
>>
>> I'm looking for a better way to handle stationary objects in Time
>> Manager.
>> For example, think of a real estate map, where plots of land change value
>> over time. The geometries themselves rarely ever change.
>>
>> Currently. It is necessary to create a join of plot geometries and values
>> over time, duplicating geometries and creating potentially huge layers.
>>
>> So far, my thoughts are going in the direction of creating query layers
>> for such cases. The query layer definition could be controlled by Time
>> Manager, to always update according to the requested time frame.
>>
>> Does that sound reasonable? Do you have other ideas or are there any
>> plans about adding temporal support to QGIS3 that I should be aware of?
>>
>
>
> ​Experiments so far (with 2.18) have turned up that virtual layers don't
> seem to support getProvider().minimumValue()
> ​which makes them unusable in Time Manger.
>


​That is minimumValue() and uniqueValues()​ seem to always just return None.

Best wishes,
Anita
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