Get Absolute URL in Blazor class

Question

Hello,

I have a class inside the Services folder.

It contains a LogError(Exception ex) method in which I need the absolute URL in order to get the requested page.

However, I am unable to access the HttpContext.Request.Url or any other method/extension that I tried.

Thank you!

Answer 1

Rather than coupling your logging code with ASP.NET a more robust solution could be just pushing any "additional properties" into some global context, like Serilog does with enrichers. Docs

This code's a bit rough & ready but hopefully puts the point across around how you might achieve this:

Logger logger = new();

string url = "..."; // Pulled from HttpContext

// With properties:
using (LogContext.PushProperty("Url", url))
{
	logger.LogException(new Exception("Failed (First)!"));
}

// Without properties:
logger.LogException(new Exception("Failed (First)!"));

public sealed class Logger
{
	public void LogException(Exception e)
	{
		var properties = new Dictionary<string, object>
		{
			{"Type", e.GetType().ToString()},
			{"Message", e.Message},
			{"StackTrace", e.StackTrace}
		};

		foreach (var property in LogContext.GetProperties())
		{
			properties.Add(property.Key, property.Value);
		}

		// Write somewhere, .e.g.
		Console.WriteLine(System.Text.Json.JsonSerializer.Serialize(properties));
	}
}

public static class LogContext
{
	private static readonly List<Property> _properties = new();

	public static Property PushProperty(string key, object value)
	{
		var property = new Property { Key = key, Value = value };

		_properties.Add(property);

		return property;
	}

	public static IEnumerable<Property> GetProperties()
	{
		foreach (var property in _properties)
		{
			yield return property;
		}
	}

	public class Property : IDisposable
	{
		public required string Key { get; init; }
		public required object Value { get; init; }

		public void Dispose()
		{
			_properties.Remove(this);
		}
	}
}

If you're familiar with ASP.NET middleware you could create one that pushes all the relevant ASP.NET context properties into LogContext by wrapping the await next.Invoke(); in a using scope like I'm doing above: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/middleware/?view=aspnetcore-9.0

Answer 2

Blazor is a single page app. HttpContext is read only and only contains the url of the page that loaded the Blazor app. To get the navigation url, you inject the NavigationManager, and use it to access the URI.