How To Return Nested JSON In C#

In this article, we will learn how to return nested JSON in C#.

JSON objects are written in key/value pairs. Values in a JSON object can be another JSON object, known as Nested JSON Objects. Accessing nested JSON objects is just like accessing nested arrays.

Let’s take one simple example of creating dynamic menus and submenus.

First, we have to create two SQL tables Menus and SubMenus as given below.

Now create the NestedMenuDTO.cs model class and add the code in it.

using System.Collections.Generic;

namespace Nested_JSON.Models
{
    public class NestedMenuDTO
    {
        public long Id { get; set; }
        public string Title { get; set; }
        public IEnumerable<SubMenu> SubMenuList { get; set; }
    }
}

Open the MenusController.cs file and add the code in it.

// GET: api/Menus                                                             
[HttpGet]
public ActionResult<IEnumerable<NestedMenuDTO>> GetMenus()
{
    List<NestedMenuDTO> nestedMenuList = new List<NestedMenuDTO>();
    var menuList = _context.Menus.ToList();
    foreach (var menu in menuList)
    {
        var nestedMenu = new NestedMenuDTO
        {
            Id = menu.Id,
            Title = menu.Title,
            SubMenuList = _context.SubMenus.Where(x => x.MenuId == menu.Id).ToList()
        };
        nestedMenuList.Add(nestedMenu);
    }
    return nestedMenuList;
}

Output:

[
    {
        "id": 1,
        "title": "Authors",
        "subMenuList": [
            {
                "id": 1,
                "title": "Yasin Panwala",
                "menuId": 1
            },
            {
                "id": 2,
                "title": "Faisal Pathan",
                "menuId": 1
            },
            {
                "id": 6,
                "title": "Tabish Rangrej",
                "menuId": 1
            }
        ]
    },
    {
        "id": 2,
        "title": "Categories",
        "subMenuList": [
            {
                "id": 3,
                "title": ".NET Core",
                "menuId": 2
            },
            {
                "id": 4,
                "title": "ASP.NET MVC",
                "menuId": 2
            },
            {
                "id": 5,
                "title": "SQL",
                "menuId": 2
            }
        ]
    },
    {
        "id": 3,
        "title": "Articles",
        "subMenuList": []
    }
]

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Also, check How To Read And Write CSV File In C#