How to get a json data that model includes text json property in asp.net web api?

Question

I have a database table named "application" in my postgresql database.

id    name     settings
----------------------------------------------------------------
1     x        "{"color":"red", "left":"30px"}"
2     y        "{"menuSize":"4", "menuOrientation":"horizontal"}"

my settings columnn has text type that includes json data as text format.

I am using this data in my asp.net web api application. The wab api can convert an object to a json data.

public class AppController : ApiController
{
    App[] apps = new App[] 
    { 
        new App { Id = 1, Name = "x" }, 
        new App { Id = 2, Name = "y" }
    };

    public IEnumerable<App> GetApps()
    {
        return apps;
    }
}

But my model includes a string property that has a json formatted data.

public class AppController : ApiController
{
    App[] apps = new App[] 
    { 
        new App { Id = 1, Name = "x", Settings = "{\"color\":\"red\", \"left\":\"30px\"}" }
    };

    public IEnumerable<App> GetApps()
    {
        return apps;
    }
}

I want to get a json response like following:

[
    {
        id: 1,
        name: "x",
        color: "color",
        left: "30px"
    }
]

all columns are converted to a json format.

Answer 1

Try to use below code to return IEnumerable<JObject> since your keys in settings is dynamic.

public IEnumerable<JObject> GetApps()
    {
        var jsonList = new List<JObject>();
        App[] apps = new App[]
       {
           new App { Id = 1, Name = "x", Settings = "{\"color\":\"red\", \"left\":\"30px\"}" },
           new App { Id = 2, Name = "y", Settings = "{\"menuSize\":\"4\", \"menuOrientation\":\"horizontal\"}" }
       };

        foreach(var app in apps)
        {
            var obj = new JObject();
            obj.Add("id", app.Id);
            obj.Add("name", app.Name);
            JObject settingsJsonObj = JObject.Parse(app.Settings);
            foreach (var property in settingsJsonObj.Properties())
            {
                var name = property.Name;
                obj.Add(name, settingsJsonObj.GetValue(name));                 
            }

            jsonList.Add(obj);
        }
        return jsonList;
    }

Result:

[
{
    "id": 1,
    "name": "x",
    "color": "red",
    "left": "30px"
},
{
    "id": 2,
    "name": "y",
    "menuSize": "4",
    "menuOrientation": "horizontal"
}
]

If you use asp.net core 3.0, you need to add a package reference to Microsoft.AspNetCore.Mvc.NewtonsoftJson and update Startup.ConfigureServices to call AddNewtonsoftJson.

services.AddMvc().AddNewtonsoftJson();

Update:

Below is a demo to use custom json converter in asp.net core 3.0 with Newtonsoft.Json;

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System;
public class AppJsonConverter : JsonConverter
{
    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {

        writer.WriteStartObject();
        {
            writer.WritePropertyName("Id");
            writer.WriteValue(value.GetType().GetProperty("Id").GetValue(value).ToString());
            writer.WritePropertyName("Name");
            writer.WriteValue(value.GetType().GetProperty("Name").GetValue(value).ToString());

            var settings = value.GetType().GetProperty("Settings").GetValue(value);
            JObject settingsJsonObj = JObject.Parse(settings.ToString());
            foreach (var property in settingsJsonObj.Properties())
            {
                var name = property.Name;
                writer.WritePropertyName(name);
                writer.WriteValue(settingsJsonObj.GetValue(name));                  

            }
        }
        writer.WriteEndObject();
    }


    public override bool CanConvert(Type objectType)
    {
        throw new NotImplementedException();
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}

Model:

[JsonConverter(typeof(AppJsonConverter))]
public class App
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Settings { get; set; }
}

Controller:

//add `using Newtonsoft.Json;`

public IEnumerable<Object> GetApps()
    {

        App[] apps = new App[]
       {
           new App { Id = 1, Name = "x", Settings = "{\"color\":\"red\", \"left\":\"30px\"}" },
           new App { Id = 2, Name = "y", Settings = "{\"menuSize\":\"4\", \"menuOrientation\":\"horizontal\"}" }
       };

        var jsonServices = JsonConvert.SerializeObject(apps);
        var result = JsonConvert.DeserializeObject<List<Object>>(jsonServices);

        return result;

    }

Answer 2

Use Newtonsoft library to parse json and then add new properties

public HttpResponseMessage  GetApps()
    JObject jsonObject = JObject.Parse("{\"color\":\"red\", \"left\":\"30px\"}");
    jsonObject.Add("id", 1);
    jsonObject.Add("name", x);

    return new HttpResponseMessage {
         Content = new StringContent(jsonObject.ToString(Formatting.None), Encoding.UTF8, "application/json"),
    };
}