C# / Function App DI sample

Startup.cs

using Microsoft.AspNetCore.Http;
using Microsoft.Azure.Functions.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection;

[assembly: FunctionsStartup(typeof(DependencyInjectionWithHttpContextSample.Startup))]

namespace DependencyInjectionWithHttpContextSample;

public class Startup : FunctionsStartup
{
    public override void Configure(IFunctionsHostBuilder builder)
    {
        builder.Services.AddScoped(s =>
        {
            var accessor = s.GetRequiredService<IHttpContextAccessor>();

            // Request header から "X-MS-CLIENT-PRINCIPAL-ID" の値を取得。
            var userId = accessor.HttpContext.Request.Headers["X-MS-CLIENT-PRINCIPAL-ID"];

            // パス "api/customers/{customerId}/order" から値を取得する
            // 今回のサンプルだと "api/customers/xyz123/order" から "xyz123" を取得する感じ。
            var path = accessor.HttpContext.Request.Path;
            var customerId = path.ToString().Split('/')[3];

            // query string の中で "hobby" の値を取得。
            var hobby = accessor.HttpContext.Request.Query["hobby"];

            return new SampleOptions
            {
                UserId = userId,
                CustomerId = customerId,
                Hobby = hobby
            };
        });
    }
}