Merge features into an existing one instead of a new one

[domi4484]

This aims to fix #47629.

• Per default the first selected feature will be preserved (other features are merged in)
• When pressing "Take attributes from selected feature" selected feature will be preserved
• When pressing "Take attributes from feature with the largest area/longest line" that feature will be preserved

[domi4484]

@andreasneumann tryng to fix this... What do you mean, what should be the default behavior when opening the merge dialog?
At the moment the "default value clause" is displayed but this does not make sense anymore. Probably it would make more sense to be "Skipped" or the id of the "master" feature.

[andreasneumann]

@andreasneumann tryng to fix this... What do you mean, what should be the default behavior when opening the merge dialog?

I think - as soon as one selects "Take attributes from the selected feature" or "Take attributes from feature with largest area" - then the primary key of the selected or largest feature should be filled in "by default" in the "Merge" record.

Thanks!

[domi4484]

I think - as soon as one selects "Take attributes from the selected feature" or "Take attributes from feature with largest area" - then the primary key of the selected or largest feature should be filled in "by default" in the "Merge" record.

Yes when pressing the buttons is quite clear. The question was more about when the dialog is just opened. I guess it would make sense to use the Id of the first selected feature.

[andreasneumann]

I guess it would make sense to use the Id of the first selected feature.

Yes, this would be fine.

It would also be fine to have "create a new feature id" by default (as it is now).

We just need a way to override this behavior - as this is not possible today.

[nyalldawson]

This approach looks on track to me 👍

[andreasneumann]

Thanks!

Can this be back-ported to 3.22.x ?

[3nids]

backporting to 3.24 should be fine.
@nyalldawson what about 3.22?

[nyalldawson]

@3nids i'm ok for that -- just has to go through the queued branch first