[QGIS-Developer] QGIS expression to get internal ID of a feature in a related layer

[Stefan Giese (WhereGroup)]

Hi Andreas,

in case of a relation 1:many you can use the /relation_aggregate/ 
function, something like:

/ relation_aggregate('test_n_318_fk_test1_7993_id','concatenate',//to_string(@id),',')/

where the first parameter is the ID of the relation.

Hope this helps...
Stefan

Am 29.11.2022 um 15:05 schrieb Andreas Neumann via QGIS-Developer:
>
> Hi,
>
> I am looking for a way to find out the internal id of a related layer 
> with a QGIS expression.
>
> @id and $id only work directly on the feature of the source layer, but 
> not on related layers.
>
> attributes(
>    get_feature(
>       'Other Related Layer',
>       't_id',
>       fkey_value
>    )
> )
>
> doesn't contain the internal id of the other layer ...
>
> Any ideas how to get access to internal ids of other layers?
>
> Thank you and greetings,
>
> Andreas
>
>
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-- 
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Stefan Giese
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