Allow merging features on non multi layers

[Paul-Losse]

Describe the issue

When attempting to merge adjacent polygons in QField, the merge button is greyed out.

Reproduction steps

Steps to reproduce the behavior:
digitise two adjacent polygons. Select one, long press on the feature to select it. Select another polygon. Select 'Merge selected feature(s). This option is greyed out

Expected behavior

'Merge selected features' button is not greyed out. Pressing the button results in merging polygons

Observed behavior

'Merge selected features' button is greyed out and not selectable. Unable to merge features

Screenshots and GIFs

[If applicable, add screenshots and GIFs to help explain your problem.]

[Please also attach additional files if a specific project/dataset is useful to investigate the problem.]

Desktop (please complete the following information)

• OS: Windows 10
• QGIS Version [e.g. 3.22.0]
• QFieldSync Version [e.g.4.0.0]

Mobile (please complete the following information)

• Device: Galaxy Tab Active 3
• OS: Android 13
• QField version: 3.1.9- Borneo (f2829b v3.1.9

Additional information

• Problem started happening recently, didn't happen in an older version of QField: Yes
• Problem can be reliably reproduced, doesn't happen randomly: Yes
• Problem happens with all files and projects, not only some files or projects: Yes

[If the problem happened with QFieldCloud, please add your username and project name.]

[nirvn]

@Paul-Losse , merging of polygons require the following conditions (https://github.com/opengisch/QField/blob/windows/src/core/multifeaturelistmodelbase.cpp#L330-L337):

• editable vector layer
• multi-type geometry (i.e. multipolygon in this case)
• data provider's ability to delete features and modify geometries

Is it possible your polygon layer is not multipolygon? If so, we can transform this as a feature request to support non multi-type geometry merging.

[m-kuhn]

Should be documented here https://docs.qfield.org/how-to/digitize/#merging-features @SeqLaz can you open a doc ticket?

[Paul-Losse]

You are correct. The polygon layer is not multipolygon. It would be great if merging could support non-multi-type geometry merging (I assumed it already did). Many thanks