QgsApplication.instance().locale() does NOT return same locale if qgis started with --lang option

[rduivenvoorde]

QGIS has some 'startup options' if started from the commandline.

One I often use is the --lang nl one, to (temporarily) start QGIS in dutch to check for example what a menu looks like in dutch.

Plugins (created with the plugin builder) for what I know check the language using (for example in Python Console):

QgsApplication.instance().locale()

BUT that (in case of starting up with --lang option) does not show the same 2char code.
Also note that in the settings at that moment the 'Ignore System Locale' is not checked and does not resemble current situation. For example below I run qgis --lang nl on an english system (it looks like the locale for numbers is changed there):

To reproduce:

• on english system
• start QGIS qgis --lang nl in cli
• see that QGIS interface is dutch
• in python console do: QgsApplication.instance().locale() and see it shows en

@m-kuhn maybe has something to do with the work for the swiss to split up locale/language and locale for the use of numbers etc ?

NOTE2: if you do this via the Settings: all is working:

Maybe that could show BOTH the system locale AND the set locale?

[elpaso]

@rduivenvoorde IMO this is not a bug. We have different independent options to configure the GUI translation and the locale.

--lang set the translation and not the locale, we might need an additional option to change locale and set the omit group separator options.

[m-kuhn]

The same also happens also the OS is configured to a language and the qgis settings are left to the default. Default plugin builder generated code will fail.

What would be good is a more stable code for plugin builder generated code to obtain the language.

[rduivenvoorde]

@elpaso I agree for some part, though that is probably too much (to add even more startup options)

And the plugin builder apparently changed! See https://github.com/g-sherman/Qgis-Plugin-Builder/blob/master/plugin_templates/toolbutton_with_dialog/template/module_name.tmpl#L51

And QSettings().value('locale/userLocale', QLocale().name()) (from plugin code) returns 'nl' if QGIS is started with --lang option, so for plugins this is fixed/fixable.

What is unclear to me is how the Settings part in the dialog should behave...

As you see in the first screenie, the (disabled! in grey) options do not represent the current state. While I started with --lang nl (which should mean: (only) language NL, locale still 'whatever') the two (disabled dropdowns) show: 'Vertaling'/'Language' is english and 'Landinstelling'/'Locale' as Dutch.

I think(!) that if started with --lang option, the checkbox 'Override System Locale' should be checked and (only) the 'User interface translation' dropdown should then reflect the --lang language?