Map appsettings.json to class

Question

I'm trying to convert appsettings.json to C# class

I use Microsoft.Extensions.Configuration to read the configuration from appsettings.json

I write the following code using reflection but I'm looking for a better solution

foreach (var (key, value) in configuration.AsEnumerable())
{
    var property = Settings.GetType().GetProperty(key);
    if (property == null) continue;
    
    object obj = value;
    if (property.PropertyType.FullName == typeof(int).FullName)
        obj = int.Parse(value);
    if (property.PropertyType.FullName == typeof(long).FullName)
        obj = long.Parse(value);
    property.SetValue(Settings, obj);
}

Options pattern solves this elegantly. Check out the offical docs. — Ash K
– Ash K, Commented Feb 13, 2024 at 19:52

Sergey Berezovskiy · Accepted Answer · 2021-01-18 22:20:48Z

23

Build configuration from appsettings.json file:

var config = new ConfigurationBuilder()
            .AddJsonFile("appsettings.json", optional = false)
            .Build()

Then add Microsoft.Extensions.Configuration.Binder nuget package. And you will have extensions to bind configuration (or configuration section) to the existing or new object.

E.g. you have a settings class (btw by convention it's called options)

public class Settings
{
    public string Foo { get; set; }
    public int Bar { get; set; }
}

And appsettings.json

{
  "Foo": "Bob",
  "Bar": 42
}

To bind configuration to new object you can use Get<T>() extension method:

var settings = config.Get<Settings>();

To bind to existing object you can use Bind(obj):

var settings = new Settings();
config.Bind(settings);

answered Jan 18, 2021 at 22:20

Sergey Berezovskiy

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3 Comments

AliReza Beigy Over a year ago

there is no Get and Bind method

Sergey Berezovskiy Over a year ago

@AliRezaBeigy then missed the part of adding Microsoft.Extensions.Configuration.Binder package

thatOneGuy Over a year ago

@AliRezaBeigy bit late, i had this, i didn't add the .Build() at the end of instantiating the config var

Karney. · Accepted Answer · 2021-01-19 10:07:07Z

4

You can use Dictionary to get the json, and then use JsonSerializer to convert the json.

public IActionResult get()
    {
        Dictionary<string, object> settings = configuration
        .GetSection("Settings")
        .Get<Dictionary<string, object>>();
        string json = System.Text.Json.JsonSerializer.Serialize(settings);

        var setting = System.Text.Json.JsonSerializer.Deserialize<Settings>(json);

        return Ok();
    }

Here is the model

public class Settings
{
    public string property1 { get; set; }
    public string property2 { get; set; }
}

In appsettings.json

 "Settings": {
  "property1": "ap1",
  "property2": "ap2"
 },

answered Jan 19, 2021 at 10:07

Karney.

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Comments

Kieran Foot · Accepted Answer · 2023-08-02 09:55:10Z

3

I'm shocked nobody has suggested using the IOptions pattern or even asked if this a system involving DI (Dependency Injection). If the system is indeed using DI, I would suggest using the IOptions pattern described here Options Pattern as it not only allows for the options to be injected where they're needed, but also allows for change notifications so you can receive configuration changes and act on them.

answered Aug 2, 2023 at 9:55

Kieran Foot

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2 Comments

Mark Schultheiss Jun 25 at 19:37

Perhaps write this up using the OP's example and present for an even better answer that is not just a link somewhere with other words that feel like a comment.

Kieran Foot Sep 18 at 9:24

Quite right. Though, I wasn't trying to provide a concise answer but point the OP in the direction of the answer to do some self learning.

Shervin Ivari · Accepted Answer · 2024-07-28 09:10:24Z

Don't reinvent the wheel! As some users have mentioned, try using the Options pattern which is provided by Microsoft.

Here is a simple example of how to do it:

appsetting.json

{
  "AppSettings": {
    "Setting1": "Value1",
    "Setting2": "Value2"
  }
}

AppOptions.cs

public class AppOptions
{
    public string Setting1 { get; set; }
    public string Setting2 { get; set; }
}

Configure it with dependency injection

services.Configure<AppOptions>(Configuration.GetSection("AppSettings"));

This is the way you inject it into service, I use IOptions, and I highly suggest checking other Options interfaces such as IOptionsSnapshot based on your case.

public SomeService(IOptions<AppOptions> appOptions)
{
    _appOptions = appOptions.Value;
}

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