Introduction

Azure Functions is a solution for easily running small pieces of code, or "functions", in the cloud. You can write just the code you need for the problem at hand, without worrying about a whole application or the infrastructure to run it. Details of the features of the Functions app are available at this link.

Features

Now let’s create an Http-triggered Azure Function App in Visual Studio.

About Http Triggered Function Apps

For HTTP-triggered functions, you can specify the authorization types needed to have in order to execute it. There are five types you can choose from the below list. Keep in mind, when running the Azure Functions locally, the authorization attribute is ignored, and you can call any function no matter which level is specified. These authorizations will work only after publishing the code in Azure. It can receive request data via query string parameters, request body data, or URL route templates. Like other functions, they can also integrate with other Azure services such as Blob Storage, Event Hubs, queues, and so on.

Authorization Types

  1. Function
  2. Anonymous
  3. Admin
  4. System
  5. User

Function

Function, Admin & System authorization levels are key-based.

Anonymous

If you want a function to be accessed by anyone, the following piece of code will work, because the authorization is set to Anonymous.

Admin

Admin authorization level requires a host key for authorization. Passing a function key will fail authorization and return an HTTP 401 – Unauthorized error code.

Create an Azure function app in Visual Studio

In Visual Studio.

Create a project by selecting File > New > Project.

Project

Select Visual C# > Cloud > Azure Functions.

Azure Functions

Click Ok.

Select HttpTrigger and Access rights > Admin.

HttpTrigger

Input Data

{  
   "userName": "[email protected]",  
   "password": "password",  
   "Employees": "{\r\n \"MethodName\": \"CheckMethod\",\r\n \"entities\": [],\r\n \"text\": \"testword\",\r\n \"isActive\": false\r\n}",  
   "IsCheck": "true"  
}

Now, I’ll create a class file with the name of CommonReturnType to read the input data.

CommonReturnType

Now, open the common return type class file.

Class file

and keep the JSON data content on the clipboard (copy input JSON data).

JSON data

Go to Edit > Paste Special > Select Paste JSON as Classes.

Paste Special

Then, an auto-generated class will be retrieved as per the JSON data.

Visual Studio

Next

Develop the code as per our requirements.

using System.Linq;  
using System.Net;  
using System.Net.Http;  
using System.Threading.Tasks;  
using Microsoft.Azure.WebJobs;  
using Microsoft.Azure.WebJobs.Extensions.Http;  
using Microsoft.Azure.WebJobs.Host;  
using Newtonsoft.Json;  

namespace FunctionApp1 
{  
    public static class Function1 
    {  
        [FunctionName("MyFirstFunction")]  
        public static async Task<HttpResponseMessage> Run(
            [HttpTrigger(AuthorizationLevel.Admin, "get", "post", Route = null)] HttpRequestMessage req, 
            TraceWriter log) 
        {  
            log.Info("C# HTTP trigger function processed a request.");  
            string jsonContent = await req.Content.ReadAsStringAsync();  
            
            if (jsonContent != "") 
            {  
                // De-serializing JSON data
                CommonReturnType fdata = JsonConvert.DeserializeObject<CommonReturnType>(jsonContent);  
                string inputMessageJSON = fdata.Employees;  
                Employees msg = JsonConvert.DeserializeObject<Employees>(inputMessageJSON);  
                
                // Process data
                if (msg.MethodName == "CheckMethod" && fdata.IsCheck == "true") 
                {  
                    string swin = msg.text;  
                    switch (swin.ToLower()) 
                    {  
                        case "something":  
                            msg.text = "How are you today";  
                            fdata.IsCheck = "true";  
                            break;  
                        
                        case "something1":  
                            msg.text = "Good Bye";  
                            fdata.IsCheck = "false";  
                            break;  
                        
                        default:  
                            msg.text = "Hi. How may I help you today..!";  
                            fdata.IsCheck = "true";  
                            break;  
                    }  
                    
                    fdata.Employees = JsonConvert.SerializeObject(msg, Formatting.Indented);  
                    return req.CreateResponse(HttpStatusCode.OK, fdata);  
                }  
            }  
            
            return req.CreateResponse(HttpStatusCode.BadRequest, "Please pass a name on the query string or in the request body");  
        }  
    }  
}

Execute the code.

Code

Test the below URL in the Postman App: http://localhost:7071/api/MyFirstFunction.

URL

If you want to publish this Azure Function in the cloud, publish this code in the Azure cloud by using credentials and publishing files.

Azure cloud

Azure URL Example

To execute this function app in Azure, you have to mention the secret key in the URL.

Example URL

http://mysite.azurewebsites.net/api/MyFirstFunction?code=MySecretCodehere

Happy coding.