Setting And Reading Values From "appsettings.json" In .NET Core

Saineshwar Bageri

10y523.1k20100Article

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Satego4y ago
Is there a way to update the data in the setting file?
NERY singer5y ago
Thank you, I was trying to do the same thing, but needing to create a class named "Settings" just to then put its data to my static Config class. Now I'm just passing the IConfiguration to my Config.Init() and it's working pretty well with half of the work.
Abdessamad Jadid5y ago
Thanks dude , this is very useful
Brian Dixon7y ago
Perhaps consider adding environment variable info and environment-specific appsettings<environment> JSON files and how they work.
- Ramesh Maruthi7y ago
  We will be having different appsettings file in that case, for an example ppsettings.development, appsettings.staging and appsettings.production and in program.cs the code looks like this
- Ramesh Maruthi7y ago
  Public class Program { public static void Main(string[] args) { CreateWebHostBuilder(args).Build().Run(); } public static IWebHostBuilder CreateWebHostBuilder(string[] args) => WebHost.CreateDefaultBuilder(args) .ConfigureAppConfiguration((hostingContext, config) => { config.AddJsonFile("appsettings.json"); config.AddJsonFile($"appsettings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ?? "Production"}.json", optional: false, reloadOnChange: false); config.AddEnvironmentVariables(); config.AddCommandLine(args); }) .UseContentRoot(Directory.GetCurrentDirectory()) .UseKestrel() .UseStartup<Startup>(); }
Mahesh Alle7y ago
Good Article. Well explained.
Sajith K7y ago
Thanks , this works like a charm
Ananth Sakthivel7y ago
Appreciate it!. Your Solution is working good. Thanks For your support.
Gopal Panda7y ago
Your Solution does not work in ASP.Net Core 2.0 and above. I have downloaded your application, that itself is configured for Core 1.1
raghav subramanian8y ago
This article is quite useful. We used to create our own "config" class which would get values populated on startup and then dependency injected into classes that need it. Thanks to these extensions we no longer need those boilerplates
Arun Sahoo8y ago
Graet Sainesh, I am working .net core 2.0 and I don't think we need to add those dlls. Could you plese edit the article with new version and IOption examle.
Kapil Jain8y ago
I have a web application made in asp.net which refer to some class library. Now I want to migrate web application to mvc core2.0. There is a class in class library which read web.config key. Now I have set all webconfig key into appsetting.json. Now appsetting keys are not found in class library. How to resolve this issue?
- CARLOS ESCOBAR8y ago
  Hi. you found how to solve this problem?
satyendra ch9y ago
Good Explanation. I want to get these configuration setting from another project DAL?
Ramesh Maruthi10y ago
Excellent Sainesh, thanks for adding that point. Why I told that specifically is, it will be less secure and performance wise it will be worse. If you load every time the complete configuration set :)
- Saineshwar Bageri10y ago
  Right sir but some one want all configuration set then they can go this way else the other way of IOptions is there
Ramesh Maruthi10y ago
Hi Saineshwara, It would be great if you add about Ioptions in asp.net core. Instead of loading complete configuration everytime. We can use this option :)
- Saineshwar Bageri10y ago
  Ya right sir we can do that also
- Saineshwar Bageri10y ago
  Appsettings.json"Data": { "ConnectionString": "Data Source=sai-pc; UID=sa; Password=#######; Database=CoreDB" }, ------------------------------------- Class public class DataClass { public string ConnectionString { get; set; } } ------------------------------------- Startup.cs class services.Configure<DataClass>(Configuration.GetSection("Data")); ------------------------------------- Constuctor Injection of Options IOptions<DataClass> _ConnectionString; public ProductConcrete(IOptions<DataClass> settings) { _ConnectionString = settings; }

Introduction

In this article, we are going to learn how to read values from "appsettings.json" file. You will ask why we want to read values from "appsettings.json" and what is there in "appsettings.json" that we would want to read it.

The "appsettings.json" file contains configuration settings. This file is similar to the Web.config file. In this file, we mostly store global values so that we can read those in the entire application. But Web.config file is in XML format and "appsettings.json" file is JSON format. We store the connection strings, keys, and value pairs mostly in "appsettings.json" file.

The way of the reading the values of Connection string and keys and value pairs in .NET application is given below.

But as we move towards .NET Core, the old style of reading values doesn’t work here. Let’s see the demo of how to set values and read values from "appsettings.json" file.

For doing this, let's create a .NET Core web application first.

Creating .Net Core web application

From Visual IDE, choose File Menu >> New >> Project.

After choosing the Project menu, a new dialog will pop up with the name “New Project”, as shown below.

Appsettings

Creating new Web application project and naming it “DemoCore”

In this dialog, just have a look at the left panel [Templates]. Inside that, you will see a new option [.NET Core]. Just choose [.NET Core].

After that, in the middle panel, you will find all project templates related to .NET Core. Select the “ASP.NET Core Web Application (.NET Core)” template.

Now, we need to name the project. Here, we are naming this project as “DemoCore”. Finally, click on OK button to create the project.

In the next step, it asks for choosing project template. Here, we are going to choose "Web Application" template and click OK.

Choosing project template

Project Structure

The project structure after choosing the web application template:

Project structure

You can see that the"appsettings.json" file is by default available in the new web application project.

Dependencies required for Using IConfiguration interface in project.json file

Dependencies required for Using IConfiguration interface in project.json file

Next, open the "appsettings.json" file in Visual Studio IDE.

appsettings.json file

Appsettings.json file opened in edit mode

After opening the file in Visual Studio Editor, add the connection string, keys, and value pairs in it.

Adding Connection String and Key and Values in Appsettings.json file

Adding new key and values in appsettings.json file

Adding new service in "ConfigureServices" Method in Startup class

In startup file, we need to add new Singleton instance in which we have passed Configuration class as instance. So, whenever we call IConfiguration Interface, their dependency injection will get an instance of Configuration class.

Note - In .NET core, dependency injection is a built-in feature.

Adding new service for reading values of Appsettings.json file

Code snippet of Adding service in Appsettings.json

public void ConfigureServices(IServiceCollection services) {
services.AddMvc();
services.AddSingleton < IConfiguration > (Configuration);
}

After adding the service, we will read the values of Connection string, keys and value pairs.

Reading values from "appsettings.json" file

We are going to use Constructor injection with the homeController for reading the values. For that, I have added a Constructor named HomeController (same as class name) which takes IConfiguration Interface as an input parameter.

At runtime, when we call HomeController, this Constructor [HomeController(IConfiguration iconfiguration)] will get called and it will get resolved by its concrete class [Configuration] which we have set in Startup class.

From now on, we are not going to create instance but we are going to ask for instance.

Reading values of Appsettings.json file

Code snippet of HomeController

using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
namespace DemoCore.Controllers {
public class HomeController: Controller {
IConfiguration _iconfiguration;
public HomeController(IConfiguration iconfiguration) {
_iconfiguration = iconfiguration;
}
public IActionResult Index() {
// First way
string value1 = _iconfiguration.GetSection("Data").GetSection("ConnectionString").Value;
// Second way
string value2 = _iconfiguration.GetValue < string > ("Data:ConnectionString");
var EmailID = _iconfiguration["EmailID"];
var Websitename = _iconfiguration["Websitename"];
var WebsiteURL = _iconfiguration["WebsiteURL"];
return View();
}
public IActionResult About() {
ViewData["Message"] = "Your application description page.";
return View();
}
public IActionResult Contact() {
ViewData["Message"] = "Your contact page.";
return View();
}
public IActionResult Error() {
return View();
}
}
}

Debugging View while reading values from Appsettings.json file

Snapshot of home controller while reading values from Appsettings.json file