The CookieConsentService.CookiePreferencesChanged event is called two times

[TomasMejzr]

Hi,
I think there might be an issue with the CookieConsentService.CookiePreferencesChanged event:

BytexDigital.Blazor.Components.CookieConsent/BytexDigital.Blazor.Components.CookieConsent/CookieConsentService.cs

Line 55 in 83da45a

public event EventHandler<CookiePreferences> CookiePreferencesChanged;

I use the CookieConsentHandler component in InteractiveServer render mode (without prerender).
I'm handling the CookieConsentService.CookiePreferencesChanged event, but the event fires two times. I thought, it was the issue with CookiePreferences equality check:
#39

That is a bug, but it didn't resolve the issue.

After further investigation, I found it has something to do with the CookieConsentEventHandler broadcasting the CookiePreferencesChanged event:

BytexDigital.Blazor.Components.CookieConsent/BytexDigital.Blazor.Components.CookieConsent/Broadcasting/CookieConsentEventHandler.cs

Lines 54 to 60 in 83da45a

	public async Task BroadcastCookiePreferencesChangedAsync(CookiePreferences cookiePreferences)
	{
	_ = Task.Run(() => CookiePreferencesChanged?.Invoke(this, cookiePreferences));
	await PublishToJsAsync(JsBroadcastEventCookiePreferencesChanged,
	JsonSerializer.Serialize(cookiePreferences));
	}

Unlike the other events this one doesn't check _runtimeContext.RendersUserInterface.
It calls the event on the server and then publishes that event to JS towards WASM. Which in turn pops again from javascript as a second call.

As I've said, the component is in the InteractiveServer render mode.
I uderstand the intention for the component to be render mode agnostic, but in this case this doesn't seem to function correctly.

When I comment one of those callings, the event fires only once as expected.

Could You please check this scenario in InteractiveServer render mode ?

Thanks.

[RyanTT]

Hey,

when you say the event fires two times, do you mean it fires two times in the same context (2 times on the server in your case) or once on the server and once in the WASM app?

[TomasMejzr]

Yes, in the same context - 2 times on the server.

The RegisterBroadcastReceiver function in javascript console writes "CookieConsent: Registered context for Server".

The PublishToJsAsync method publishes the event to cookieconsent.js. And it seems the following code broadcasts the event back to the server context.

BytexDigital.Blazor.Components.CookieConsent/BytexDigital.Blazor.Components.CookieConsent/wwwroot/cookieconsent.js

Lines 133 to 141 in 83da45a

	BroadcastEvent: function (toWasm, eventName, eventDataJson) {
	console.log("CookieConsent: Broadcasting " + eventName + " (toWasm=" + toWasm + ") with data " + eventDataJson);
	if (toWasm && window.CookieConsentContext.Broadcasting.WasmContext !== null) {
	window.CookieConsentContext.Broadcasting.WasmContext.invokeMethodAsync("OnReceivedBroadcastAsync", eventName, eventDataJson);
	} else if (window.CookieConsentContext.Broadcasting.ServerContext !== null) {
	window.CookieConsentContext.Broadcasting.ServerContext.invokeMethodAsync("OnReceivedBroadcastAsync", eventName, eventDataJson);
	}
	},

Then this method is called:

BytexDigital.Blazor.Components.CookieConsent/BytexDigital.Blazor.Components.CookieConsent/Broadcasting/CookieConsentEventHandler.cs

Lines 86 to 108 in 83da45a

	[JSInvokable("OnReceivedBroadcastAsync")]
	public Task OnReceivedBroadcastAsync(string name, string data)
	{
	_ = name switch
	{
	JsBroadcastEventCookiePreferencesChanged => Task.Run(()
	=> CookiePreferencesChanged?.Invoke(this, JsonSerializer.Deserialize<CookiePreferences>(data))),
	JsBroadcastEventShowConsentModalRequested => Task.Run(()
	=> ShowConsentModalRequested?.Invoke(this, EventArgs.Empty)),
	JsBroadcastEventShowPreferencesModalRequested => Task.Run(()
	=> ShowPreferencesModalRequested?.Invoke(this, EventArgs.Empty)),
	JsBroadcastEventScriptLoaded => Task.Run(()
	=> ScriptLoaded?.Invoke(this,
	JsonSerializer.Deserialize<CookieConsentScriptLoadedArgs>(data))),
	_ => throw new ArgumentOutOfRangeException(nameof(name), name, "Event name not known.")
	};
	return Task.CompletedTask;
	}

And the CookieConsentEventHandler.CookiePreferencesChanged is fired again.

[RyanTT]

Hm, I'll need to debug this. The call to JS is correct, as this is to give possible WASM components the chance to change their state as the user preferences change, even if the UI is running in the server. But the call shouldn't circle back to the server in this case.

When the call is being made, what does your browser console log for this line?

BytexDigital.Blazor.Components.CookieConsent/BytexDigital.Blazor.Components.CookieConsent/wwwroot/cookieconsent.js

Line 134 in 83da45a

console.log("CookieConsent: Broadcasting " + eventName + " (toWasm=" + toWasm + ") with data " + eventDataJson);

[RyanTT]

Oh, actually, I see what's happening. It's a logic error in the if statement. I'll fix it today and push an update.

[RyanTT]

I've pushed a preview version, could you let me know if it works as expected now?

https://www.nuget.org/packages/BytexDigital.Blazor.Components.CookieConsent/1.2.2-preview.1751592594