Layer user notes only available for QgsVectorLayer when reading a project with flag QgsProject.FlagDontResolveLayers

[jmkerloch]

What is the bug or the crash?

When a QgsProject is read from a file with flag QgsProject.FlagDontResolveLayers we can get layer user notes only for QgsVectorLayer

I looked into the code for differences between QgqVectorLayer and other layer (for instance QgsRasterLayer).

For QgsRasterLayer the main difference is that we never load symbology if the data provider is not set (consequence of the QgsProject.FlagDontResolveLayers flags:

QGIS/src/core/raster/qgsrasterlayer.cpp

Lines 2410 to 2420 in 6bf3ee0

	if ( ! mDataProvider )
	{
	if ( !( mReadFlags & QgsMapLayer::FlagDontResolveLayers ) )
	{
	QgsDebugError( QStringLiteral( "Raster data provider could not be created for %1" ).arg( mDataSource ) );
	}
	return false;
	}
	QString error;
	const bool res = readSymbology( layer_node, error, context );

Steps to reproduce the issue

1. Create a QGIS project
2. Load a vector layer
3. Add a layer note to this vector layer
4. Load a raster layer
5. Add a layer note to this raster layer
6. Save QGIS project
7. Run this python code

qgs_project = QgsProject()
path = "/path/to/created/qgis_project.qgz"
project_qgs.read(path, QgsProject.FlagDontResolveLayers)

for name, layer in project_qgs.mapLayers().items():
    print(f"{name=} {QgsLayerNotesUtils.layerNotes(layer)=}")

There should be a layer note available for all layers.

Versions

<style type="text/css"> p, li { white-space: pre-wrap; } </style>

QGIS version	3.36.3-Maidenhead	QGIS code revision	2df9655
Qt version	5.15.3
Python version	3.10.12
GDAL/OGR version	3.4.1
PROJ version	8.2.1
EPSG Registry database version	v10.041 (2021-12-03)
GEOS version	3.10.2-CAPI-1.16.0
SQLite version	3.37.2
PDAL version	2.3.0
PostgreSQL client version	14.11 (Ubuntu 14.11-0ubuntu0.22.04.1)
SpatiaLite version	5.0.1
QWT version	6.1.4
QScintilla2 version	2.11.6
OS version	Ubuntu 22.04.3 LTS
Active Python plugins
plugin_reloader	0.11
french_locator_filter	1.1.1
processing	2.12.99
MetaSearch	0.3.6
grassprovider	2.12.99
db_manager	0.1.20
menu_from_project	2.2.0-beta1

QGIS version 3.36.3-Maidenhead QGIS code revision [2df9655](https://github.com/qgis/QGIS/commit/2df9655469b) Qt version 5.15.3 Python version 3.10.12 GDAL/OGR version 3.4.1 PROJ version 8.2.1 EPSG Registry database version v10.041 (2021-12-03) GEOS version 3.10.2-CAPI-1.16.0 SQLite version 3.37.2 PDAL version 2.3.0 PostgreSQL client version 14.11 (Ubuntu 14.11-0ubuntu0.22.04.1) SpatiaLite version 5.0.1 QWT version 6.1.4 QScintilla2 version 2.11.6 OS version Ubuntu 22.04.3 LTS

Active Python plugins
plugin_reloader
0.11
french_locator_filter
1.1.1
processing
2.12.99
MetaSearch
0.3.6
grassprovider
2.12.99
db_manager
0.1.20
menu_from_project
2.2.0-beta1

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

I need to access layer user note for the plugin https://plugins.qgis.org/plugins/menu_from_project/

This plugin allow user to have a menu with all layer and group inside a QGIS project.

To avoid manual parsing of the .xml for QGIS project we would like to go with a QgsProject that already have all the needed informations.