QgsPathResolver::readPath/writePath: make it work properly with OGR datasource URI

[rouault]

(fixes #55975)

[github-actions]

🪟 Windows builds ready!

Windows builds of this PR are available for testing here. Debug symbols for this build are available here.

(Built from commit 351dfa4)

[nyalldawson]

@rouault isn't this a bug in QgsOgrProviderMetadata::relativeToAbsoluteUri / QgsOgrProviderMetadata::absoluteToRelativeUri instead ?

Those methods don't use QgsOgrProviderMetadata::decodeUri/QgsOgrProviderMetadata::encodeUri, whereas others like QgsMdalProviderMetadata::relativeToAbsoluteUri use encode/decode uri to only pass the file path through the QgsPathResolver methods.

[rouault]

isn't this a bug in QgsOgrProviderMetadata::relativeToAbsoluteUri / QgsOgrProviderMetadata::absoluteToRelativeUri

Those methods aren't called by QgsPathResolver::readPath() / writePath(), which is what is used for project loading/saving (cf QgsLayerTreeLayer::writeXml()). They actually implement a workaround for the 'fix' I did in readPath()/writePath()
Probably that a rewrite of readPath()/writePath() using provider metadata relativeToAbsoluteUri() would be cleaner, but I'd be worried of breaking stuff

[nyalldawson]

Hmm, so shouldn't QgsLayerTreeLayer::writeXml / readXml be adapted to use the correct method? Ie instead of:

    elem.setAttribute( QStringLiteral( "source" ), context.pathResolver().writePath( mRef->publicSource() ) );
    elem.setAttribute( QStringLiteral( "providerKey" ), mRef->dataProvider() ? mRef->dataProvider()->name() : QString() );

it should be something like:

    const QString providerKey = mRef->dataProvider() ? mRef->dataProvider()->name() : QString();
    const QString source = providerKey.isEmpty() ? mRef->publicSource() : QgsProviderRegistry::instance()->relativeToAbsoluteUri( providerKey, mRef->publicSource(), context );
    elem.setAttribute( QStringLiteral( "source" ), source );
    elem.setAttribute( QStringLiteral( "providerKey" ), providerKey  );

(It's weird here that publicSource is used instead of source, but let's not touch that!)

[rouault]

Hmm, so shouldn't QgsLayerTreeLayer::writeXml / readXml be adapted to use the correct method? Ie instead of:

Thanks for the suggestion. It seems to solve the issue. Closing that one as superseded per #55988