This is a twofold issue. I'm collecting pictures with QField and trying to rename them using this expression 'DCIM/' || "fid" || '_' || format_date(now(),'yyMMdd_hhmmss') || '.jpg'
in the QField panel of the layer properties.
The first issue is that I want to use the "fid" field of a geometry layer, while the Photo naming settings for Qfield are those ones of the related table (where there is another "fid" fields).
The second issue is that although the expression appears correct, pictures are named like
"DCIM\JPEG_20220614054141828.jpg"
as in this question, not even considering the "fid" of the table layer.
The naming should work also in case of more than one person working at the same time on the field and adding features and taking pictures simultaneously. The project is successively updated via Qfield Cloud to participant's devices.