Asp net core change appsettings at runtime

Introduction

ASP.NET is a popular programming language used for building web applications. One common requirement in web development is the ability to change app settings at runtime. This article will discuss how to achieve this in ASP.NET Core.

AppSettings in ASP.NET Core

In ASP.NET Core, app settings are typically stored in the appsettings.json file. This file contains key-value pairs that define various configuration settings for the application. By default, these settings are read-only and cannot be modified at runtime.

Modifying AppSettings at Runtime

There are several approaches to modify app settings at runtime in ASP.NET Core. One common approach is to use the Configuration API provided by the framework.

Using the Configuration API

The Configuration API in ASP.NET Core allows you to access and modify app settings programmatically. To use this API, you need to inject the IConfiguration interface into your class.

public class MyController : Controller
{
    private readonly IConfiguration _configuration;

    public MyController(IConfiguration configuration)
    {
        _configuration = configuration;
    }

    public IActionResult Index()
    {
        // Get the current value of an app setting
        var settingValue = _configuration["MySetting"];

        // Modify the value of an app setting
        _configuration["MySetting"] = "NewValue";

        return View();
    }
}

In the above example, we inject the IConfiguration interface into the MyController class. This allows us to access and modify app settings using the _configuration object.

Reloading AppSettings

By default, the Configuration API caches the app settings and does not automatically reload them when they are modified. To enable automatic reloading, you can use the IOptionsMonitor interface.

public class MyController : Controller
{
    private readonly IConfiguration _configuration;
    private readonly IOptionsMonitor _optionsMonitor;

    public MyController(IConfiguration configuration, IOptionsMonitor optionsMonitor)
    {
        _configuration = configuration;
        _optionsMonitor = optionsMonitor;
    }

    public IActionResult Index()
    {
        // Get the current value of an app setting
        var settingValue = _configuration["MySetting"];

        // Modify the value of an app setting
        _configuration["MySetting"] = "NewValue";

        // Reload the app settings
        _optionsMonitor.Reload();

        return View();
    }
}

In the above example, we inject the IOptionsMonitor interface into the MyController class. This interface allows us to reload the app settings using the _optionsMonitor.Reload() method.

Conclusion

Modifying app settings at runtime is a common requirement in web development. In ASP.NET Core, you can achieve this by using the Configuration API and the IOptionsMonitor interface. By following the examples provided in this article, you should be able to easily modify app settings in your ASP.NET Core applications.