Transfer attributes from parent to child feature using @current_parent_feature

[cratcliff]

I'm trying to transfer values from a parent feature to a child by using attribute(@current_parent_feature,'Site') as the default expression and then use the values for photo filenames.

I am trying to use @current_parent_feature over other solutions like attribute(get_attribute( ) ) as the layer name/id and relationship name/ids will change.

Currently the values from the parent are retrieved and displayed in child form correctly, but aren't saved or accessible unless edited (i.e. add a space/hyphen). As a result they aren't accessible by the photo naming expression either.

Is it possible to use @current_parent_feature in this way with Qfield?

The following shows the behavior I am experiencing.

I have also included a simplified QGIS project & packaged QField project to demonstrate.

I am using QGIS 3.36.2-Maidenhead for Windows, QField Sync 4.9.1 and Qfield 3.2.2-Congo on Android 14 (Samsung Active 4 Pro).

[m-kuhn]

Thank you for reporting this, @cratcliff

We have made a couple of improvements in this area, could you check if this is still an issue with QField 3.3?

[cratcliff]

@m-kuhn Yes, it is still an issue. I'm now using Qfield 3.3.1-Darien(6b9cd v3.3.1) and QGIS 3.36.3-Maidenhead.

[cratcliff]

@m-kuhn I've just upgraded again to 3.3.2 Darien (a2b463 v3.3.2) and it is still an issue.

[nirvn]

@cratcliff , thanks for providing a test project. A fix to the issue raised in this discussion has been found. You can test the APKs that will appear here to confirm it works as expected: #5356

[9ls1]

@current_parent_feature doesn't seem to work in 3.7.9? See #6862

[9ls1]

@cratcliff, did you test the APK and can you confirm that @current_parent_feature works in the photo naming expression? I can't get it working in QField version 3.7.9.

[9ls1]

Problem solved, thanks to @FelixHinckel, see https://community.qfield.org/t/using-current-parent-feature-in-filename-expression-not-working/1379

[Kalana-maduranga001]

Is @current_parent_feature expected to work in photo naming expressions in QField, or is it currently limited to form display only?

[Kalana-maduranga001]

When using attribute(@current_parent_feature, 'field') as a default value in a child layer, should the value be persisted automatically on save, or is manual editing required for it to be stored?

[FelixHinckel]

For photo naming, you can use the fonction, rater than the variable :
current_parent_value( 'Field' ) works very well for me

I use it as a default value for a field in the child layer, and then use that field in photo naming

[Kalana-maduranga001]

Thanks for the suggestion

Using the function instead of the variable solved the issue for me.

For photo naming, @current_parent_feature does not seem to be reliably resolved, but using:

current_parent_value('Field')
works correctly.

I now use current_parent_value('Field') as the default value for a field in the child layer, and then reference that stored child field in the photo naming expression. With this approach, the value is properly saved and consistently available when the photo is created.

This seems to be the recommended workaround for photo naming when parent attributes are required, without relying on layer or relationship IDs.

Hope this helps others running into the same issue.