Add Nullable annotation support in MudBlazor.

[ScarletKuro]

Is your feature request related to a problem?

Update the codebase with nullable reference types to improve null diagnostic warnings, more info here.

Not only end user will benefit from this, but also the codebase quality will increase.
NullReferenceException would be much rare. For example, currently the DataGrid suffers from this issue.
Nowadays, the <Nullable>enable</Nullable> is the default when you create a new projects.

List of projects that has the nullable enabled on the project level

• MudBlazor.Docs.Server
• MudBlazor.Docs.Wasm - MudBlazor.Docs.Wasm: enable nullable #7068
• MudBlazor.Docs.WasmHost - WasmHost / Examples.Data: Add nullable annotation. #8963
• MudBlazor.Examples.Data - WasmHost / Examples.Data: Add nullable annotation. #8963
• MudBlazor.Docs

List of components that should be annotated
Base:

• MudComponentBase - was added in this pr MudAvatar: Add nullable annotation #6543
• MudFormComponent - MudFormComponent: Add nullable annotation. #6608
• MudBooleanInput - MudBooleanInput: Add nullable annotation. #6681
• MudBaseButton - MudBaseButton: Add nullable annotation. #7136
• MudBaseInput - MudBaseInput: Add nullable annotation. #8635

Misc:

• Extensions - Extensions: Add nullable annotation. #7151

Components:

• Alert - MudAlert: Add nullable annotation. #6539
• AppBar - MudAppBar: Add nullable annotation #6540
• Autocomplete
• Avatar - MudAvatar: Add nullable annotation #6543
• Badge - MudBadge: Add nullable annotation. #6554
• Breadcrumbs - MudBreadcrumbs: Add nullable annotation. #7126
• BreakpointProvider - MudBreakpointProvider: Add nullable annotation. #6720
• Button - Buttons: Add nullable annotation. #7427
• ButtonGroup - MudButtonGroup: Add nullable annotation. #6640
• Card - MudCard: Add nullable annotation. #7428
• Carousel - MudCarousel: Add nullable annotation. #7138
• Chart
• CheckBox - MudCheckBox: Add nullable annotation. #7082
• Chip - MudChip and MudChipset: Support Generic #4342
• ChipSet - MudChip and MudChipset: Support Generic #4342
• Collapse - MudCollapse: Add nullable annotation and Async AnimationEnd. #6747
• Container - MudContainer: Add nullable annotation. #7075
• DataGrid
• DataPicker
• Dialog
• Divider - MudDivider: Add nullable annotation. #6641
• Drawer - MudDrawer: Add nullable annotation. #7186
• DropZone - MudDropZone: Add nullable annotation and fix #6551, #4695. #6561
• Element - MudElement: Add nullable annotation. #7083
• ExpansionPanel - MudExpansionPanels: Add nullable annotation. #6976
• Field - MudField: Add nullable annotation. #6642
• FileUpload - MudFileUpload: Add nullable annotation #8392
• FocusTrap - MudFocusTrap: Add nullable annotation. #7331
• Form
• Grid - MudGrid: Add nullable annotation. #8900
• Hidden - #MudHidden: Add nullable annotation. #7087
• Highlighter - MudHighlighter: Add nullable annotation. #6731
• Icon - MudIcon: Add nullable annotation. #6578
• Image - MudImage: Add nullable annotation. #6997
• Input
• InputControl - MudInputControl: Add nullable annotation. #7340
• Layout - MudLayout: Add nullable annotation. #7148
• Link - MudLink: Add nullable annotation. #7175
• List - MudList: Add Nullable and use ParameterState #8297
• Main - MudMainContent: Add nullable annotation. #6664
• Mask
• Menu - MudMenu: Add nullable annotation. #8632
• MessageBox - MudMessageBox: Add nullable annotation. #7137
• NavMenu - MudNavMenu: Add nullable annotation. #7176
• NumericField
• Overlay - MudOverlay: Add nullable annotation. #6665
• PageContentNavigation - MudPageContentNavigation: Add nullable annotation. #7125
• Pagination - MudPagination: Add nullable annotation. #7124
• Paper - MudPaper: Add nullable annotation. #7084
• Picker
• Popover - PopoverService: New design #6953
• Progress - MudProgress: Add nullable annotation. #6993
• RTLProvider - MudRTLProvider: Add nullable annotation. #7073
• Radio - MudRadio: Add nullable annotation. #7366
• Rating - MudRating: Add nullable annotation. #7069
• Render - MudRender: Add nullable annotation. #7149
• ScrollToTop - MudScrollToTop: Add nullable annotation. #7114
• Select
• Skeleton - MudSkeleton: Add nullable annotation. #7113
• Slider - MudSlider: Add nullable annotation. #7077
• Snackbar
• Spacer - doesn't require any changes.
• Sparkline - MudSparkLine: Add nullable annotation. #7152
• Stack - MudStack: Add nullable annotation. #7071
• SwipeArea - MudSwipeArea: Add nullable annotation. #7072
• Switch - MudSwitch: Add nullable annotation. #7088
• Table - MudTable: Add nullable annotation. #8926
• TableSimple - MudSimpleTable: Add nullable annotation. #6679
• Tabs
• TextField
• ThemeProvider - MudThemeProvider: Add nullable annotation #7097
• TimePicker
• Timeline - MudTimeline: Add nullable annotation #7096
• ToolBar - MudToolBar: Add nullable annotation #7095
• Tooltip - MudTooltip: Add nullable annotation #7094
• TreeView - TreeView: Fix the ParameterView instance has expired. #8361, MudTreeView: Fix selection issues #7810
• Typograpgy - MudText: Add nullable annotation. #6677
• Virtualize - MudVirtualize: Add nullable annotation. #6678

I will volunteer and do 1 component at time when I get the time.

Describe the solution you'd like

Plan:

1. Pick a component.
2. Add preprocessor directive - #nullable enable to component files.
3. Properly annotate the code.
4. Submit the PR.

Repeat until no components left to annotate and enable enable on project leave and remove the preprocessor directive.
Rule: Don't make multiple components at once since it will be hard to review.

Technical aspects

This doesn't force the user to use nullable, nothing will change for people who doesn't use Nullable in their application, it will work as it is now..
Technically, this is not API change. In fact, the compiler adds additional metedata: NullableAttribute and NullableContextAttribute.
Example:

public string? Name { get; set; }

Transform to

[Nullable(2)]
[CompilerGenerated]
private string __BackingField;

[Nullable(2)]
public string Name
{
  [NullableContext(2), CompilerGenerated] get
  {
	return this.__BackingField;
  }
  [NullableContext(2), CompilerGenerated] [param: In] set
  {
	this.__BackingField = value;
  }
}

This says that the property Name can be null. It's just added some metadata around.
But people who have the nullable enabled will notice the difference.
Let's say I'm MudBlazor user and call Name.ToString() the Roslyn will warn me saying that you should check for null since the Name can be null and I get the NullReferenceException.

Now the opposite, if there is no ? on Name means that it's guaranteed by the library to always have a value and I can safely call Name.ToString() without checking for null.
If I as a MudBlazor user try to assign null to Name Roslyn will also warn me that this is not desired.

Have you seen this feature anywhere else?

BlazorStrap, fluentui-blazor(MS) - surprisingly, many UI Blazor frameworks don't support it.
But if we look more widely, then most popular Nuget packages do support it, including the .NET BCL.

Pull Request

• I would like to do a Pull Request

Code of Conduct

• I agree to follow this project's Code of Conduct

[github-actions]

👋 Thanks for wanting to do a PR @ScarletKuro !
We suggest that you wait for an answer from @MudBlazor/contribution-team @MudBlazor/core-team . Otherwise we can not guarantee that your PR will be merged. As the library grows, we have to be very strict what PRs we can accept.