How to retain state of a revisited page?

[benny856694]

I want to retain the sate of the page, is there a good way?
using a singleton class to hold the sate and inject to the page?

[MattParkerDev]

Yes, a simple AppState pattern can be used if you want to load the data for a page from in memory.

public class AppState
{
	public string? MyProperty { get; set; }
}

Then yes, register it as a singleton:

// Program.cs
appBuilder.Services.AddSingleton<AppState>();

Then it can be injected into a page:

@* MyPage.razor *@
@inject AppState AppState

And used like so:

@code {
	private string? _myProperty;

	protected override void OnInitialized()
	{
		_myProperty = AppState.MyProperty;
	}
}

Be aware of the gotcha that if you bind any UI elements to properties on AppState, updating any values in AppState from a different view will not cause a re-render of the current view - you will need to manually trigger it yourself somehow.

[benny856694]

seem no better way

[benny856694]

Yes, a simple AppState pattern can be used if you want to load the data for a page from in memory.

public class AppState
{
	public string? MyProperty { get; set; }
}

Then yes, register it as a singleton:

// Program.cs
appBuilder.Services.AddSingleton<AppState>();

Then it can be injected into a page:

@* MyPage.razor *@
@inject AppState AppState

And used like so:

@code {
	private string? _myProperty;

	protected override void OnInitialized()
	{
		_myProperty = AppState.MyProperty;
	}
}

Be aware of the gotcha that if you bind any UI elements to properties on AppState, updating any values in AppState from a different view will not cause a re-render of the current view - you will need to manually trigger it yourself somehow.

thanks, I watched your YouTube video, great sharing.