Saving To appsettings.json

Question

I'd like to be able to use a form to enable users to edit a custom section of the appsettings.json file. I can't find any documentation on how to accomplish this, I'm currently building a web app using VS 2019 and .NET 5.

Answer 1

Hi, JamesTankersley

To edit appsettings.json in a form, you can check my demo:

IWritableOptions：

public interface IWritableOptions<out T> : IOptions<T> where T : class, new()
    {
        void Update(Action<T> applyChanges);
    }

WritableOptions：

public class WritableOptions<T> : IWritableOptions<T> where T : class, new()
    {
        private readonly IHostingEnvironment _environment;
        private readonly IOptionsMonitor<T> _options;
        private readonly IConfigurationRoot _configuration;
        private readonly string _section;
        private readonly string _file;

        public WritableOptions(
            IHostingEnvironment environment,
            IOptionsMonitor<T> options,
            IConfigurationRoot configuration,
            string section,
            string file)
        {
            _environment = environment;
            _options = options;
            _configuration = configuration;
            _section = section;
            _file = file;
        }

        public T Value => _options.CurrentValue;
        public T Get(string name) => _options.Get(name);

        public void Update(Action<T> applyChanges)
        {
            var fileProvider = _environment.ContentRootFileProvider;
            var fileInfo = fileProvider.GetFileInfo(_file);
            var physicalPath = fileInfo.PhysicalPath;

            var jObject = JsonConvert.DeserializeObject<JObject>(File.ReadAllText(physicalPath));
            var sectionObject = jObject.TryGetValue(_section, out JToken section) ?
                JsonConvert.DeserializeObject<T>(section.ToString()) : (Value ?? new T());

            applyChanges(sectionObject);

            jObject[_section] = JObject.Parse(JsonConvert.SerializeObject(sectionObject));
            File.WriteAllText(physicalPath, JsonConvert.SerializeObject(jObject, Formatting.Indented));
            _configuration.Reload();
        }
    }

ServiceCollectionExtensions：

public static class ServiceCollectionExtensions
    {
        public static void ConfigureWritable<T>(
            this IServiceCollection services,
            IConfigurationSection section,
            string file = "appsettings.json") where T : class, new()
        {
            services.Configure<T>(section);
            services.AddTransient<IWritableOptions<T>>(provider =>
            {
                var configuration = (IConfigurationRoot)provider.GetService<IConfiguration>();
                var environment = provider.GetService<IHostingEnvironment>();
                var options = provider.GetService<IOptionsMonitor<T>>();
                return new WritableOptions<T>(environment, options, configuration, section.Key, file);
            });
        }
    }

Model:

public class Locations
    {
        public Locations()
        {
            Name ="default";
        }
        public string Name { get; set; }
    }

Controller:

private readonly IWritableOptions<Locations> _writableLocations;
        public HomeController(IWritableOptions<Locations> writableLocations)
        {
            _writableLocations = writableLocations;
        }

        //Update Locations:Name
        public IActionResult Change(string value)
        {
            _writableLocations.Update(opt => {
                opt.Name = value;
            });
            return RedirectToAction("Index");
        }

View:

<form asp-action="Change" method="post">
    <input name="value" type="text"/>
    <input type="submit"  value="submit"/>
</form>

And add this service to startup:

services.ConfigureWritable<Locations>(Configuration.GetSection("Locations"));

Result:

Best Regards,
Jerry Cai

---

If the answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

Hi @Jerry Cai-MSFT
Thank you for all explications.
I would like how I can Relaod/Refrech services after the changing of AppSettings.json.
Thanks