MudSlider: Add nullable value parameter

[ScarletKuro]

Description

Fixes: #8860 (comment)

How Has This Been Tested?

Type of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation (fix or improvement to the website or code docs)

Checklist

• The PR is submitted to the correct branch (dev).
• My code follows the code style of this project.
• I've added relevant tests.

[ScarletKuro]

@henon @danielchalmers is this good enough?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.22%. Comparing base (28bc599) to head (f14a0d4).
Report is 152 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #8881      +/-   ##
==========================================
+ Coverage   89.82%   90.22%   +0.39%     
==========================================
  Files         412      424      +12     
  Lines       11878    12286     +408     
  Branches     2364     2406      +42     
==========================================
+ Hits        10670    11085     +415     
+ Misses        681      669      -12     
- Partials      527      532       +5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[henon]

I guess that resolves it just fine. In the example a Button to reset the nullable value to null would be awesome.

[henon]

Added to v7.0.0 Migration Guide #8447

[ScarletKuro]

Updated example

There is another breaking change:
RenderFragment<T> -> RenderFragment<SliderContext<T>> as we now need both values..

[ScarletKuro]

I will add explicit bUnit test if @danielchalmers approves this approach.

[ScarletKuro]

The alert is not relevant anymore in the example. Added trick that it will work when you two way bind two values.

I noticed that now when the knob is in the begging and since it stays at zero, if you touch the knob but not move it the value update will not trigger means the nullabeValue will also stay null. I don't think i can force input to trigger the binding when value actually didn't update. But it seems like it behaves in other frameworks like angular's mat-slider same way. I don't know if this is a problem

[henon]

If it becomes a problem we'll find a solution later. Hasn't been one in 3+ years so don't hold your breath ;)

[danielchalmers]

Thanks @ScarletKuro. I think it's strange that you have to use a different binding when Value works for the other inputs but I'm just looking forward to having the functionality.

I updated to the new property (Point.SleepHours is decimal?)

- <MudSlider @bind-Value="Point.SleepHours" Variant="Variant.Filled" Min="0" Max="24" Step="0.5m" Size="Size.Large" Immediate />
+ <MudSlider @bind-NullableValue="Point.SleepHours" Variant="Variant.Filled" Min="0" Max="24" Step="0.5m" Size="Size.Large" Immediate />

But get build errors:

Argument 2: cannot convert from 'Microsoft.AspNetCore.Components.EventCallback<decimal?>' to 'Microsoft.AspNetCore.Components.EventCallback'

The type or namespace name 'T' could not be found in the global namespace (are you missing an assembly reference?)

If I add T="decimal?" (which I'm not surprised doesn't work):

The type 'decimal?' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'MudSlider<T>'

[ScarletKuro]

If I add T="decimal?" (which I'm not surprised doesn't work):

Try T=decimal

[ScarletKuro]

<MudSlider T="decimal" @bind-NullableValue="_point.SleepHours" Variant="Variant.Filled" Min="0" Max="24" Step="0.5m" Size="Size.Large" Immediate />

@code {
    private readonly Point _point = new();

    public class Point
    {
        public decimal? SleepHours { get; set; }
    }
}

This just works for me. I guess blazor is having hard time to guess the generics in this case. Since some values are int(min, max) some are decimals (step) and the bind value is nullable.
Btw, Immediate is the default behavior in the slider.

If I add T="decimal?" (which I'm not surprised doesn't work):

You are not suppose to set decimal? in the generics as the NullableValue is already a Nullable, it's just decimal.

[ScarletKuro]

I think it's strange that you have to use a different binding when Value works for the other inputs

Well, we discussed multiples times before if having two value bindings is an adequate solution, and we agreed with @henon that it is.
We even planned to use it in datepicker, but then realized there is too much combinations DateTime, DateOnly, DateTimeOffset + nullable variants.

[danielchalmers]

+<MudSlider T="decimal" @bind-NullableValue="Point.SleepHours" Variant="Variant.Filled" Min="0" Max="24" Step="0.5m" Size="Size.Large" />

Worked 👍

[ScarletKuro]

Added tests.
Feel free to merge whenever if these changes are ok.

[henon]

Thanks!