QGIS » QGIS Application

It is not a question of preventing a user from overwriting a parameter with his own values if it is a deliberate act.

But the system as it is currently designed freezes all parameters in the QGIS.INI if only one change is made by a user. Any later changes to the default settings in the global_settings are then no longer taken into account, except for the addition of new variables.

Do you mean array parameters?

Can you please show an example?

The example I am confronted with is the following:

we add in global_settings a path to a plugin directory:

customEnvVars=customEnvVars, "overwrite|QGIS_PLUGINPATH=T:\\configuration_qgis\\plugins"

if the user adds a variable to describe a service name for its layout. All variables, including QGIS_PLUGINPATH are written in QGIS.INI
If QGIS_PLUGINPATH is modified in global_settings, the new value is overwritten by the value stored in QGIS.INI

Ok, I see what's happening, I'm not sure this case was in the original specification but it makes sense to me: if a value has not changed from the default value it should not be stored in user settings.

Would this solve your issue?

Thank you. I think this new approach solves problems.

As we focus on the deployment of QGIS 3.4 LTR, is it possible to backport the modification?

Finally I am not sure that the proposed patch solves my particular case.

Indeed, if a user adds a custom variable, he modifies custEnvVars.
The test line 287 will therefore be true and QGIS_PLUGINPATH will be stored in QGIS.ini.

What do you think about?

Sorry but I don't understand: if the user adds/modify custEnvVars (on any other setting) it will be stored in the user settings and the defaults from global settings will not be used.

That's the idea behind the global settings: to be able to provide default values.

For any other settings manipulation you'd need more sophisticated approaches, I did some work on that in the past, you need to start from a startup.py script that manipulates the user settings before QGIS starts.

The difficulty with custom environment variables is that you may want some to be stored in global_setting.ini while leaving the user the option to add their own.

Unfortunately QGIS stores all environment variables as a single string in CustEnvVars which is therefore necessarily in QGIS.INI as soon as the user adds a local variable.

I understand that this is sophisticated approache.

Startup.py may be a solution...
I am interested by examples if they exist....

This is my old work: https://connect.boundlessgeo.com/docs/desktop/latest/system_admins/init_scripts.html it was developed for QGIS 2 but you get the idea.

Je crains que le correctif n'ait produit un effet de bord indésirable
see #21464

I'm afraid the patch has produced an undesirable side effect
see #21464