[QGIS-Developer] QgsProcessingParameterMultipleLayers does not seem to use optional parameter

[Håvard Tveite]

I guess that an empty list of layers is regarded as acceptable,
as long as the parameter is present in the call.
Perhaps you can use setMinimumNumberInputs to achieve what you
want?

Something like:

           self.addParameter(
               QgsProcessingParameterMultipleLayers(
                   self.INPUT_LINES, self.tr <http://self.tr>("Lines"),
                   QgsProcessing.TypeVectorLine,
                   optional=False
               ).setMinimumNumberInputs(1)
           )

Håvard

On 04.03.2020 10:02, Jean-Charles Quillet wrote:
> Hello,
> 
> I develop a processing algorithm for the toolbox. One of my parameters a list of
> vector layers of type line, so in my initAlgorithm function I have this statement:
> 
>           self.addParameter(
>               QgsProcessingParameterMultipleLayers(
>                   self.INPUT_LINES,
> self.tr <http://self.tr>("Lines"),
>                   QgsProcessing.TypeVectorLine,
>                   optional=False
>               )
>           )
> 
> However, even if the optional parameter is set to False, it seems the user can
> still set an empty list: so not setting anything actually. So for me, this
> optional parameter doesn't work in this case.
> 
> Am I missing something here or is it a bug ? In this last case, I can report it
> on github. I'm using QGIS on Windows 3.10.2-A Coruña
> 
> Thanks,
> 
> Jean-Charles
>