Table of Contents

BLAZMVVM0017: RelayCommand Async Pattern

Diagnostic Information

  • Diagnostic ID: BLAZMVVM0017
  • Category: Blazing.Mvvm
  • Severity: Warning
  • Title: Async RelayCommand method should return Task

Description

An asynchronous method marked with CommunityToolkit.Mvvm's [RelayCommand] attribute should return Task, not void. Returning Task lets the generated command use AsyncRelayCommand, observe exceptions, and expose asynchronous execution state.

The analyzer matches the CommunityToolkit attribute by its full type name, so unrelated attributes named RelayCommand do not trigger the rule.

Examples

❌ Incorrect

[RelayCommand]
private async void Save() // BLAZMVVM0017
{
    await SaveChangesAsync();
}

✅ Correct

[RelayCommand]
private async Task Save()
{
    await SaveChangesAsync();
}

Code Fix

The code fix changes the return type from void to Task and adds using System.Threading.Tasks when needed. It leaves the method name unchanged so references and the generated command name remain stable.

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