reading arrays of objects from appsettings.json

Question

{  
  "Logging": {  
    "LogLevel": {  
      "Default": "Information",  
      "Microsoft.AspNetCore": "Warning"  
    }  
  },  
  "AllowedHosts": "*",  
  "TimeInterval": [  
     {  
      "Title": "6 hours",  
      "Hours": 6  
    },  
    {  
      "Title": "1 day",  
      "Hours": 24  
    }  
  ]  
}  

Above is what i have in my appsettings.json. I am able to read single properties of objects however i cant read the whole array at once. Preferably i'd like to parse it into a TimeInterval object too. How can I do this? I am using blazor server side.

Answer 1

You should use Dependency Injection and the .NET Configuration system:

1. Inject IConfiguration, and store the instance in a member/variable like Configuration
2. Add the using Microsoft.Extensions.Configuration statement
3. Read the app settings like this: var intervals = Configuration.GetSection("TimeInterval").Get<List<TimeInterval>>();

You can also use options pattern to get the settings. But to avoid a long post, I'll just share two examples on how to get configs in the page or in a page model. Fore more information, take a look at links at the bottom of the post.

Example 1 - Getting configuration in a Blazor Page

Assuming you have the following class:

public class TimeInterval  
{  
    public string Title { get; set; }  
    public int Hours { get; set; }  
}  

Then in a page, you can inject IConfiguration and read the settings:

@page "/"  
@using Microsoft.Extensions.Configuration  
@inject IConfiguration Configuration  
<h1>Hello, world!</h1>  
<ul>  
@{  
    var intervals = Configuration.GetSection("TimeInterval").Get<List<TimeInterval>>();  
    foreach (var item in intervals)  
    {  
        <li>@item.Title: @item.Hours Hours</li>  
    }  
}  
</ul>  
Welcome to your new app.  

Example 2 - Getting configuration in a PageModel class:

Inject the IConfiguration and read settings like this:

using Microsoft.AspNetCore.Mvc.RazorPages;  
using Microsoft.Extensions.Configuration;  
using System.Collections.Generic;  
  
namespace WebApplication1.Pages  
{  
    public class IndexModel : PageModel  
    {  
        public IConfiguration Configuration;  
        public IndexModel(IConfiguration configuration)  
        {  
            Configuration = configuration;  
        }  
        public void OnGet()  
        {  
            var intervals = Configuration.GetSection("TimeInterval").Get<List<TimeInterval>>();  
        }  
    }  
}  

More information:

• ASP.NET Core Blazor configuration - App Setting Configuration
• Configuration in ASP.NET Core
• Options pattern

Answer 2

One option using System.Text.Json

public class RootSettings  
{  
    public Timeinterval[] TimeInterval { get; set; }  
}  

Read

Timeinterval[] result =  
    JsonSerializer.Deserialize<RootSettings>(  
        File.ReadAllText("appsettings.json")).TimeInterval;