[QGIS-Developer] Backward compatibility for style in project files between QGIS versions

[Jésahel Benoist]

Hi,

We have remarked such breaking compatibility format problem. The more
annoying for us being the layout style, with font format being lost, so we
have to correct everything. I planned to inspect the file as you did, your
work will be useful.

Thank you !

Jésahel Benoist
Service des Risques Urbains et Sanitaires
Ville de Lille

Le jeu. 27 avr. 2023 à 08:08, FERRATON Alain (Adjoint au chef de groupe) -
SG/DNUM/MSP/DS/GSG via QGIS-Developer <qgis-developer at lists.osgeo.org> a
écrit :

> Hi
>
> A polygon layer saved in a project file with QGIS 3.28 is systematically
> opened in blue in QGIS 3.16 (the style is lost).
>
> There has been a change in the storage of style in project files
> introduced in QGIS 3.22.
>
> QGIS 3.22 save the style in both formats (<Option.../>
>
> and <prop k=.../>
>
> (see the attachment)
>
> This is no longer the case in QGIS 3.28
>
> We have a heterogeneous QGIS version park. The non backward compatibility
> of style is an important brake to migrate progressively our services to
> QGIS 3.28
>
> We could consider developing or having developed a plugin to ensure this
> backward compatibility.
> Is this possible? What would be the best way to proceed? Can we find
> documentation on the storage of styles in QGIS project files and on its
> evolution?
> (I didn't find anything relevant by searching on the internet).
>
> Sincerely,
> --
>
> *Alain FERRATON*
> Adjoint au chef de groupe
> MSP/DS/GSG
> Direction du numérique | Secrétariat général
>
> MAN 7, rue René Viviani 44200 NANTES
> Bureau : MAN étage 1 plateau B
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