How to Read AppSettings from a JSON File in ASP.NET Core?

Read AppSettings values ​​from .json file in ASP.NET Core

Introduction

In ASP.NET Core, it is a common practice to store application settings in .json files. This article provides a comprehensive guide on how to read and access these values ​​in an ASP.NET Core application.

Accessing AppSettings from a .json file

1. Configure configuration pipeline:

<code class="language-csharp">public Startup(IConfiguration configuration)
{
    Configuration = configuration;
}</code>

2. Retrieve the AppSettings section:

<code class="language-csharp">IConfigurationSection appSettingsSection = Configuration.GetSection("AppSettings");</code>

Example usage

To access specific values ​​in "AppSettings":

<code class="language-csharp">string token = appSettingsSection["token"];</code>

Option Mode

ASP.NET Core 2.0 introduces options mode as the recommended method of accessing configuration settings. This mode allows you to bind configuration to a specific class.

1. Define your configuration class:

<code class="language-csharp">public class MyConfig
{
    public string Token { get; set; }
}</code>

2. Configure AppSettings binding:

<code class="language-csharp">public void ConfigureServices(IServiceCollection services)
{
    services.AddOptions();
    services.Configure<MyConfig>(Configuration.GetSection("AppSettings"));
}</code>

3. Inject class instance:

<code class="language-csharp">public class MyController : Controller
{
    private readonly MyConfig _appSettings;

    public MyController(IOptions<MyConfig> appSettings)
    {
        _appSettings = appSettings.Value;
    }

    string GetToken() => _appSettings.Token;
}</code>

Additional Notes

• ASP.NET Core automatically registers the "appsettings.json" file in the root directory.
• The "appsettings.{Environment}.json" file can be used to override settings based on the environment.
• To reload configuration changes during development, set reloadOnChange: true.

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