How to do it…

Perform the following steps:

1. Navigate to the Function App listing page by clicking on the Function Apps menu, which is available on the left-hand side.
2. Create a new function by clicking on the + icon:

1. You will see the Azure Functions for .NET - getting started page, where you will be prompted to choose the type of tools you would like to use. You can choose the one you are the most interested in. For the initial few chapters, we will use the In-portal option, where you can quickly create Azure Functions right from the portal without any tools. Later, in the following chapters, we will use Visual Studio and Azure Functions Core Tools to create our functions:

1. Next select More templates and click on Finish and view templates, as shown in the following screenshot:

1. In the Choose a template below or go to the quickstart section, choose HTTP trigger to create a new HTTP trigger function:

1. Provide a meaningful name. For this example, I have used RegisterUser as the name of the Azure Function.
2. In the Authorization level drop-down, choose the Anonymous option. We will learn more about the all authorization levels in Chapter 9, Implementing Best Practices for Azure Functions:

1. Click on the Create button to create the HTTP trigger function.

1. As soon as you create the function, all the required code and configuration files will be created automatically and the run.csx file will be opened for you so that you can edit the code. Remove the default code and replace it with the following code. I have added two parameters (firstname and lastname), which will be displayed in the output when the HTTP trigger is triggered:

#r "Newtonsoft.Json"

using System.Net;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Primitives;
using Newtonsoft.Json;

public static async Task<IActionResult> Run(
                    HttpRequest req, 
                    ILogger log)
{
  log.LogInformation("C# HTTP trigger function processed a request.");
  string firstname=null,lastname = null;
  string requestBody = await new StreamReader(req.Body).ReadToEndAsync();

 dynamic inputJson = JsonConvert.DeserializeObject(requestBody);
 firstname = firstname ?? inputJson?.firstname;
 lastname = inputJson?.lastname;

 return (lastname + firstname) != null
 ? (ActionResult)new OkObjectResult($"Hello, {firstname + " " + lastname}")
 : new BadRequestObjectResult("Please pass a name on the query" + "string or in the request body");
}

1. Save these changes by clicking on the Save button, which is available just above the code editor.
2. Let's try and test the RegisterUser function using the Test console. Click on the Test tab to open the Test console:

1. Enter the values for firstname and lastname in the Request body section:

Make sure that you select POST in the HTTP method drop-down.

1. Once you have reviewed the input parameters, click on the Run button, which is available at the bottom of the Test console:

1. If the input request workload is passed correctly with all the required parameters, you will see a Status 200 OK, and the output in the Output window will be like what's shown in the preceding screenshot.