ControlDoublePrivate::getControl returning NULL for ( "[EffectRack1_EffectUnit1]" , "num_effects" )

[Jörg Wartenberg]

I use the following code section in my mapping:

 for (let macroFxUnitIdx = 1; macroFxUnitIdx <= 2; macroFxUnitIdx++) {
        let numOfLoadedButDisabledEffects = 0;
        let numOfLoadedandEnabledEffects = 0;
        for (let effectIdx = 1; effectIdx <= engine.getValue("[EffectRack1_EffectUnit" + macroFxUnitIdx + "]", "num_effects"); effectIdx++) {
            if (engine.getValue("[EffectRack1_EffectUnit" + macroFxUnitIdx + "_Effect" + effectIdx + "]", "loaded") === 1) {
                if (engine.getValue("[EffectRack1_EffectUnit" + macroFxUnitIdx + "_Effect" + effectIdx + "]", "enabled") === 1) {
                    numOfLoadedandEnabledEffects++;
                } else {
                    numOfLoadedButDisabledEffects++;
                }
            }
        }
   }

This worked without failure, using Main versions from ~spring 2021. Now I updated to the latest Main and get the following warning:
warning Controller ControlDoublePrivate::getControl returning NULL for ( "[EffectRack1_EffectUnit1]" , "num_effects" )
warning Controller Unknown control "[EffectRack1_EffectUnit1]" "num_effects" , returning 0.0
warning Controller ControlDoublePrivate::getControl returning NULL for ( "[EffectRack1_EffectUnit2]" , "num_effects" )
warning Controller Unknown control "[EffectRack1_EffectUnit2]" "num_effects" , returning 0.0

With return value 0, the loop is longer executed of cause, and the mapping does not work as expected anymore. The CO is stillin the manual for 2.4, so I supposeit should still work: https://manual.mixxx.org/2.4/en/chapters/appendix/mixxx_controls.html#control-[EffectRack1_EffectUnitN]-num_effects

[Jan Holthuis (holthuis-jan)]

This is a regression caused by https://github.com/mixxxdj/mixxx/commit/535a717e2b0793c566dfe1aea8de292d330c1ec5

[Jan Holthuis (holthuis-jan)]

In your case you probably want to use `num_effectslots` instead of `num_effects` anyway.

However, we must not remove COs (which is basically a breaking API change) without at least documenting that change.

[Jörg Wartenberg (joerg-ubuntu)]

It seems num_effectslots does the job for my case as well. Maybe num_effects is redundant. I don't understand, what was the difference between them, both return the value 4, while 3 slots are visible.

The only official mapping which contains it, is res/controllers/Reloop-Jockey-3-ME-scripts.js, but there it's commented out.

[Jörg Wartenberg (joerg-ubuntu)]

Should I open a PR to remove num_effects from the manual? Or will this be fixed otherwise?

[Daniel Schürmann (daschuer)]

A PR is welcome.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/10638