MultiSelect - showToggleAll not working as expected

[dfernandez-elastic]

Describe the bug

When using MultiSelect, we have a use case where we need to pass the selectionLimit prop conditionally. Like this:

<p-multiSelect 
    [options]="cities" 
    [(ngModel)]="selectedCities" 
    optionLabel="name"
    [showToggleAll]="true"
    [selectionLimit]="someCondition ? '3' : null" 
    placeholder="Select Cities" />

This is the most recommended way to pass props conditionally.

So, in the MultiSelect component, you have a method to show/hide the Toggle All checkbox. The problem comes in this line where you are transforming the selectionLimit variable. When passing null or undefined, this transform is transforming the variable to NaN, so later your isSelectionAllDisabled method is not working as expected because ObjectUtils.isEmpty(NaN) is false.

At the end, when passing null or undefined to the selectionLimit prop, we end up not showing the Toggle All checkbox at all.

Do you have a workaround? Or other recommended way?

Thanks a lot

Last note:

Angular people told me that this is the expected behaviour for the numberAttribute transform

Environment

Reproducer

https://stackblitz.com/edit/pi4qot?file=src%2Fapp%2Fmulti-select-basic-demo.html

Angular version

18.1.0

PrimeNG version

17.18.2

Build / Runtime

Angular CLI App

Language

TypeScript

Node version (for AoT issues node --version)

v22.4.1

Browser(s)

No response

Steps to reproduce the behavior

No response

Expected behavior

I should see the Toggle All checkbox when passing null or undefined to the selectionLimit prop