Min/max dates are not disabled in popup

[sleptsov]

Bug description:

Dates in datepicker popup do not set to disabled state when use dynamic [minDate]/[maxDate] with custom date adapter

In a forked demo from ng-bootstrap Custom date adapter and formatter you can see that min/max is set dynamically from component class and disabled in basic UI mode, but not in a popup UI mode, if remove (comment out) custom adapter from providers array dates (min/max) are becoming disabled

Link to minimally-working StackBlitz that reproduces the issue:

https://stackblitz.com/edit/angular-oetchw

Versions of Angular, ng-bootstrap and Bootstrap:

Angular: 8.2.14

ng-bootstrap: 5.3.0

Bootstrap: 4.4.1

[artopaavola]

This seems to have been working correctly in 5.2.1 and is broken in 5.2.2 ->

[ar41bald]

I have the same issue even with the built-in NgbDateNativeAdapter.

Link to minimally-working StackBlitz that reproduces the issue:

https://stackblitz.com/edit/angular-zdyuru?file=app%2Fdatepicker-popup.ts

As I can see in the date-picker sourcecode the problem is that this provided adapter is used to convert @input minDate/maxDate (using toModel method) but it shouldn't as minDate/maxDate are always NgbDateStruct objects by design.
Here is the line from ng-bootstrap source code

this._cRef.instance.minDate = this._dateAdapter.toModel(changes.minDate.currentValue);
...
this._cRef.instance.maxDate = this._dateAdapter.toModel(changes.maxDate.currentValue);

After these lines executed with the changes like this: {year: 2020, month: 3, day: 1}, minDate/maxDate are set to JS Date objects and then they couldn't pass validation in the NgbDatePickerService and became null

    let patch = Object.keys(options)
                    .map(key => this._VALIDATORS[key](options[key]))
                    .reduce((obj, part) => ({...obj, ...part}), {});

In my opinion, the solution is - refactor setting minDate/maxDate changes to avoid transforming them by any adapter.

[maxokorokov]

@ar41bald thanks for getting to the bottom of this issue. Confirm it was broken in 5.2.2, apologies it took so long.

Fix should be released in 5.3.1 and 6.0.3