HttpClient base address is missing trailing slash

[danroth27]

The HttpClient base address reflects the base path of the app, which is great, but it's missing the trailing slash:

<base href="/foo/" />

@inject HttpClient Http

@functions {
    protected override async Task OnInitAsync()
    {
        Console.WriteLine(Http.BaseAddress); // Expected: <base-uri>/foo/, Actual: <base-uri>/foo
    }
}

The problem seems to be here:

https://github.com/aspnet/Blazor/blob/a9c45fe78ac18b6bd524904b40896c249f9f09c0/src/Microsoft.AspNetCore.Blazor.Browser/Services/BrowserUriHelper.cs#L146-L158

[SteveSandersonMS]

Can you provide a repro of something that is broken as a consequence? I thought the trailing slash was not expected for the HttpClient, but we'd have a definite confirmation I'm wrong if there was a repro case.

[danroth27]

The fetch data request to pull down the JSON data fails when the site is hosted at a base path other than the root. For example, if the site is hosted at http://foo.github.io/blazor and you specify the base path as <base href="/foo/" /> then the HttpClient base address is http://foo.github.io/blazor. If you then make a request to sample-data/weather.json then the HttpClient makes a request to http://foo.github.io/sample-data/weather.json, when it should go to http://foo.github.io/blazor/sample-data/weather.json.

By URI resolution rules:

• http://foo.github.io/blazor + sample-data/weather.json = http://foo.github.io/sample-data/weather.json
• http://foo.github.io/blazor/ + sample-data/weather.json = http://foo.github.io/blazor/sample-data/weather.json

[danroth27]

using System;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApp2
{
    class Program
    {
        static async Task Main(string[] args)
        {
            var client1 = new HttpClient(new NoopMessageHandler());
            client1.BaseAddress = new Uri("http://locahost/foo");
            var response = await client1.GetAsync("bar");

            var client2 = new HttpClient(new NoopMessageHandler());
            client2.BaseAddress = new Uri("http://locahost/foo/");
            response = await client2.GetAsync("bar");
        }
    }

    public class NoopMessageHandler : HttpMessageHandler
    { 
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            Console.WriteLine(request.RequestUri);
            return Task.FromResult(new HttpResponseMessage());
        }
    }
}

Output:

http://locahost/bar
http://locahost/foo/bar