| license | MIT |
| name | author-component |
| description | Create or review Blazor components (.razor files) with correct architecture. USE FOR: writing new Blazor components that do NOT involve JavaScript interop, implementing parameters and EventCallback, RenderFragment slots, component lifecycle (OnInitializedAsync, OnParametersSet), async patterns, IAsyncDisposable, CancellationToken, CSS isolation, code-behind. DO NOT USE FOR: creating new projects (use create-blazor-project), JavaScript interop or calling browser APIs from Blazor (use use-js-interop), forms and validation (use collect-user-input), prerendering issues (use support-prerendering), HTTP data fetching patterns (use fetch-and-send-data), coordinating state between unrelated components (use coordinate-components).
|
Author Blazor Component
Core Rules
- Data flows down via
[Parameter]. Events flow up via EventCallback<T> (never Action/Func).
- Never mutate
[Parameter] properties. Copy to a private field in OnParametersSet.
- Use
[Parameter] public T Prop { get; set; } — never required or init (causes BL0007).
- Use
[EditorRequired] for required parameters.
- Handle all states: loading, empty, loaded, error — each with
@if/@else.
- Use
@key on repeated elements in loops for efficient diffing.
- Use
IReadOnlyList<T> (not IEnumerable<T>) for collection parameters.
RenderFragment & Generics
[Parameter] public RenderFragment? ChildContent { get; set; }
[Parameter] public RenderFragment<TItem>? RowTemplate { get; set; }
Use @typeparam TItem for generic components.
File Patterns
- Single-file:
.razor with @code block when logic < ~50 lines.
- Code-behind:
.razor + .razor.cs with partial class when logic > ~50 lines.
Disposal
Implement IAsyncDisposable (not IDisposable) when the component owns subscriptions, timers, or CTS.
In DisposeAsync: unsubscribe (-=), cancel CTS, dispose resources. Never call StateHasChanged.
Async Patterns
await every async operation. Never use .Result, .Wait(), Task.Run, ContinueWith, Thread.Start.- Debounce:
Task.Delay + CancellationTokenSource. Cancel old CTS, create new, await delay, do work. Never use System.Threading.Timer or System.Timers.Timer.
- Polling: Loop in
OnInitializedAsync with await Task.Delay(interval, token) — stays on sync context.
- External events (
Action<T>): Use async void handler + await InvokeAsync(() => { state++; StateHasChanged(); }) + catch → DispatchExceptionAsync. Never _ = InvokeAsync(...).
- Cancel CTS in
DisposeAsync. Don't catch ObjectDisposedException — use CTS cancellation.
Don'ts
required/init on [Parameter] — runtime failure- Mutate
[Parameter] — copy to private field in OnParametersSet
Action/Func for events — use EventCallback<T>Task.Run/.Result/.Wait()/Timer for debounce — deadlock or thread-pool escape- Inline
style attributes — use CSS classes or data-* attributes
catch { throw; } — use when guard or let exceptions propagate- Gold-plating: ARIA, wrapper divs, accessibility features not requested
_ = InvokeAsync(...) — swallows exceptions; use async void + DispatchExceptionAsync
