ServerHostedLogging.md

Blazor Server Hosted model console logging

About

Blazor extension for logging to browser console. Important NOTE: this package only works for apps using Server Hosting Model!

Features

Logger

This package implements Microsoft Extensions Logging abstraction to support using of ILogger and ILogger<T> interface for Server Blazor Console logging.

When this package installed and configured all logs written by ILogger and ILogger<T> will reach Browser console logger and log messages will appear in the browser's developer tools Console tab.

Log levels

The logger supports the LogLevels defined by Microsoft LogLevel enum.

Configuration

Installation

package Majorsoft.Blazor.Server.Logging.Console is available on NuGet.

dotnet add package Majorsoft.Blazor.Server.Logging.Console

Use the --version option to specify a preview version to install.

Setup

Blazor Server hosted model requires more complicated setup. Since your code runs on the Sever and logs has to be transfered to the Browser.

Follow the next 3 required steps to make it work.

Step 1. Register service and LoggerProvider

Add the following code snippet to your Server hosted Blazor Application. Into the Program.cs file 'CreateHostBuilder' method.

using Majorsoft.Blazor.Server.Logging.Console;

...

public static IHostBuilder CreateHostBuilder(string[] args) =>
	Host.CreateDefaultBuilder(args)
		.ConfigureLogging(logger =>
		{
			logger.AddBrowserConsole()
			  .SetMinimumLevel(LogLevel.Trace) //Setting LogLevel is optional NOTE: appsettings.json config overrides this
			  .AddFilter("Microsoft", LogLevel.Information); //System logs can be filtered
		})
		.ConfigureWebHostDefaults(webBuilder =>
		{
			webBuilder.UseStartup<Startup>();
		});

Step 2. Register SignalR Hub

All SignalR Hubs must be registered with MapHub method in the Startup.cs file Configure method.

public void Configure(IApplicationBuilder app)
{
	...
	app.UseEndpoints(endpoints =>
	{
		//Blazor server code
		endpoints.MapBlazorHub();
		endpoints.MapFallbackToPage("/_Host");
		//Logging setup
		endpoints.MapHub<BlazorServerConsoleLoggingHub>(BlazorServerConsoleLoggingHub.HubUrl);
	});
}

Step 3. Start SignalR connection

Initialize and start SignalR connection with Sever. It should be executed only once. Best place to do it is in MainLayout.razor file.

@using Majorsoft.Blazor.Server.Logging.Console
@inject IBrowserConsoleLoggerService _browserConsoleLogger

@implements IAsyncDisposable

@code{
	protected override async Task OnAfterRenderAsync(bool firstRender)
	{
		if(firstRender)
		{
			//setup console log
			await _browserConsoleLogger.StartLoggerAsync();
		}
	}

	public async ValueTask DisposeAsync()
	{
		if (_browserConsoleLogger is not null)
		{
			await _browserConsoleLogger.DisposeAsync();
		}
	}
}

Usage

After setup usage is very simple. Just use by standard logging with injected ILogger object. The following code snippet shows how to use logger in a Blazor component.

@using Microsoft.Extensions.Logging

@inject ILogger<Index> _logger
@code {
	protected override void OnInitialized()
	{
		_logger.LogDebug("Index init");
	}
}

The following code snippet shows how to use logger in .cs files.

using Microsoft.Extensions.Logging;

...

public class CustomCode
{
	private readonly ILogger<CustomCode> _logger;
	public CustomCode(ILogger<CustomCode> logger)
	{
		_logger = logger;
		_logger.LogDebug("CustomCode init");
	}
}