Getting Started With C# Azure Functions

using System.Collections.Generic;
using System.Net;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.Extensions.Logging;
using System.Text.Json;

namespace DemoFunctionApp
{
    public class Function1
    {
        private readonly ILogger _logger;

        public Function1(ILoggerFactory loggerFactory)
        {
            _logger = loggerFactory.CreateLogger<Function1>();
        }

        class TestModel
        {
            public string Test { get; set; }
            public string Text  { get; set; }
        }

        [Function("Function1")]
        public async Task<HttpResponseData> Run([HttpTrigger(AuthorizationLevel.Function, "post")] HttpRequestData req)
        {
            //This is how you can use the logger to log information and errors.
            _logger.LogInformation("C# HTTP trigger function processed a request.");
            _logger.LogError("This is an error message.");
            _logger.LogWarning("This is a warning message.");

            //This is how you can read url parameters.
            var query = System.Web.HttpUtility.ParseQueryString(req.Url.Query);
            string message = query["message"];

            //This is how you can get headers from the request.
            req.Headers.TryGetValues("Some-Header", out var someHeaderValues);
            string someHeader = someHeaderValues.First().ToString();

            //Read the body of the request.
            string body = await req.ReadAsStringAsync();

            //Parse the JSON body into a model.
            TestModel model = JsonSerializer.Deserialize<TestModel>(body);

            //Get an environmental variable.
            if (Environment.GetEnvironmentVariable("TEST_ENVAR") == model.Test)
            {
                //Create a text response.
                var responseTest = req.CreateResponse(HttpStatusCode.NoContent);
                responseTest.Headers.Add("Content-Type", "text/plain; charset=utf-8");

                //Add text to response.
                responseTest.WriteString("Test. Query param: " + message);

                //Return the response.
                return responseTest;
            }
            else 
            {
                var response = req.CreateResponse(HttpStatusCode.OK);
                response.Headers.Add("Content-Type", "text/plain; charset=utf-8");

                response.WriteString("Not test. Query param: " + message);

                return response;
            }
        }
    }
}