How to read AppSettings values from a .json file in ASP.NET Core?

Question

Aryan Kumar · Answer

Sure. Here is how to read appsettings values from a .json file in ASP.NET Core:
Create a .json file and add the appsettings values that you want to read. For example, the following .json file defines an appsetting named "MySetting":
JSON
{
  "MySetting": "My Value"
}
In your ASP.NET Core application, add the following code to your Startup.cs file:
C#
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
  // ...
  // Add the appsettings file to the configuration.
  app.UseAppSettingsFile("appsettings.json");
  // Read the appsetting value.
  var mySetting = app.Configuration["MySetting"];
  // Do something with the appsetting value.
  Console.WriteLine(mySetting);
}
Run your ASP.NET Core application and the appsetting value will be printed to the console.
Here is a breakdown of the code:
The UseAppSettingsFile() method adds the appsettings file to the configuration.The app.Configuration["MySetting"] property gets the value of the appsetting named "MySetting".The Console.WriteLine() method prints the appsetting value to the console.
You can also use the ConfigurationManager class to read appsettings values from a .json file. The following code is equivalent to the code above:
C#
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
  // ...
  // Read the appsetting value using the ConfigurationManager class.
  var mySetting = ConfigurationManager.AppSettings["MySetting"];
  // Do something with the appsetting value.
  Console.WriteLine(mySetting);
}
However, the ConfigurationManager class is deprecated in ASP.NET Core 3.0 and later. You should use the
app.Configuration property instead.
If you are using a .NET Core 2.1 or earlier version, you can use the ConfigurationManager class to read appsettings values from a .json file. However, it is recommended to upgrade to a newer version of .NET Core and use the
app.Configuration property instead.

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How to read AppSettings values from a .json file in ASP.NET Core?

Utpal Vishwas

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