How to override list configuration in .net

Question

I have hard time to find out solution for an issue regarding binding values from configuration files.

I have configuration option containing list initialized in code, for example

public List<string> availableFruit { get; set; } = new List<string> { "apple", "banana", "pineapple",};

But I want to change it in config file where I have

{
  "Store": {
    "AvailableFruit": [
      "watermelon"
    ]
  }
}

The binding now works that way, that it adds config in file to the previously initialized in code, thus it results in "apple, banana, pineapple, watermelon", but I want to have only watermelon.

I digged through code and found out, that .net has it hardcoded in configuration binder that it uses "Add" method. I also tried to create new method where I wanted override the method, but that was not possible.

Is there any way, how can I do that?

//EDIT: I call it as this

services.Configure<StoreOptions>(Configuration.GetSection("Store"));

Answer 1

public class JsonHelper
{
    /**
     *  JsonHelper.JsonFileAddParameter("~/app.json", "hot", "YEEE");
     * */
    public static void JsonFileAddParameter(string path, string parameter, string value)
    {
        if (String.IsNullOrEmpty(value))
            throw new ArgumentNullException("Value");
        if (String.IsNullOrEmpty(parameter))
            throw new ArgumentNullException("Parameter");

        dynamic treatments;
        string _path = HostingEnvironment.MapPath(path);

        using (StreamReader sr = new StreamReader(_path))
        {
            treatments = JsonConvert.DeserializeObject(sr.ReadToEnd());
            sr.Close();
        }
        
        //JObject property = new JObject( new JProperty(parameter, value) );
        treatments[parameter] = value;
        File.WriteAllText(_path, String.Empty);
        string json = JsonConvert.SerializeObject(treatments);
        File.WriteAllText(_path, json);
    }



    /**
     *  JsonHelper.JsonFileEdit("~/app.json", "AppKey", "123456789");
     * */
    public static void JsonFileEdit(string path, string parameter, string editValue)
    {
        if (String.IsNullOrEmpty(editValue))
            throw new ArgumentNullException("Edit Value");
        if (String.IsNullOrEmpty(parameter))
            throw new ArgumentNullException("Parameter");

        dynamic treatments;
        string _path = HostingEnvironment.MapPath(path);

        using (StreamReader sr = new StreamReader(_path))
        {
            treatments = JsonConvert.DeserializeObject(sr.ReadToEnd());
            sr.Close();
        }

        if (treatments[parameter] == null)
            throw new ArgumentNullException(parameter);

        treatments[parameter] = editValue;
        File.WriteAllText(_path, String.Empty);
        string json = JsonConvert.SerializeObject(treatments);
        File.WriteAllText(_path, json);
    }


    /**
     *  var lol = JsonHelper.JsonReader("~/app.json", "AppKey");
     * */
    public static dynamic JsonReader(string path, string parameter)
    {
        dynamic treatments;

        using (StreamReader sr = new StreamReader(HostingEnvironment.MapPath(path)))
        {
            treatments = JsonConvert.DeserializeObject(sr.ReadToEnd());
            sr.Close();
        }

        return treatments[parameter];
    }



    /**
     * var lol = JsonHelper.Json("~/package.json");
     * */
    public static dynamic JsonReader(string path)
    {
        /**
         *  using(StreamReader sr = new StreamReader(Server.MapPath("~/Content/treatments.json")))
            {
                  treatments = JsonConvert.DeserializeObject<List<Treatment>>(sr.ReadToEnd());
            }
         * */
        dynamic treatments;

        using (StreamReader sr = new StreamReader(HostingEnvironment.MapPath(path)))
        {
            treatments = JsonConvert.DeserializeObject(sr.ReadToEnd());
            sr.Close();
        }
        
        return treatments;
    }
}