Deserialize Json string with child objects

Question

Got the following structure given:

public class TaskList
{
    public string Name { get; set; }
    public List<ToDoTask> ToDoTasks { get; set; }
}

public class ToDoTask
{
    public string Name { get; set; }
    public string Note { get; set; }
    public DateTime LastEdit { get; set; }
    public bool Finished { get; set; }
}

I'm using System.Text.Json in .NET 5.0 to serialize a List successfully into a json-file:

JsonSerializerOptions serializeOptions = new() { WriteIndented = true };
string json = JsonSerializer.Serialize(taskLists, serializeOptions);

the result looks fine:

{
  "TaskLists": [
    {
      "Name": "List1",
      "ToDoTasks": [
        {
          "Name": "Task1",
          "Note": "",
          "LastEdit": "2022-04-19T13:05:10.0415588+02:00",
          "Finished": false
        },
        {
          "Name": "Task2",
          "Note": "",
          "LastEdit": "2022-04-19T13:05:13.9269202+02:00",
          "Finished": false
        }
      ]
    },
    {
      "Name": "List2",
      "ToDoTasks": [
        {
          "Name": "Task3",
          "Note": "",
          "LastEdit": "2022-04-19T13:05:18.3989081+02:00",
          "Finished": false
        },
        {
          "Name": "Task4",
          "Note": "",
          "LastEdit": "2022-04-19T13:05:23.0949034+02:00",
          "Finished": false
        }
      ]
    }
  ]
}

When I deserialize this json-file, I only got the TaskLists but the ToDoTasks, are empty.

List<TaskList> taskLists = JsonSerializer.Deserialize<List<TaskList>>(json);

What do I have to do, get also the ToDoTask-Childs included into the deserialized objects?

Please provide your .NET version – Jacek Ratajewski Apr 19 '22 at 11:30 — Jacek Ratajewski, Apr 19 '22 at 11:30
It's .NET 5.0, I've added it to the post – Seraphim Apr 19 '22 at 11:47 — Seraphim, Apr 19 '22 at 11:47

score 1 · Answer 1 · answered Apr 19 '22 at 11:47

Whenever you cannot figure out your model class, you can use Visual Studio's Edit - Paste Special - Paste JSON as Class to check out.

Your model classes should be like this:

public class Rootobject
{
    public Tasklist[] TaskLists { get; set; }
}

public class Tasklist
{
    public string Name { get; set; }
    public Todotask[] ToDoTasks { get; set; }
}

public class Todotask
{
    public string Name { get; set; }
    public string Note { get; set; }
    public DateTime LastEdit { get; set; }
    public bool Finished { get; set; }
}

And you can Deserialize it:

static void Main(string[] args)
{
    var query = JsonSerializer.Deserialize<Rootobject>(File.ReadAllText("data.json"));
}

score 0 · Answer 2 · answered Apr 19 '22 at 11:40

0

Your json has a root object containing the task list, so List<TaskList> does not represent it correctly. Try:

public class Root
{
    public List<TaskList> TaskLists { get; set; }
}

var root = JsonSerializer.Deserialize<Root>(json);

answered Apr 19 '22 at 11:40

Guru Stron

102,774
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Exactly the same result. That alos was my first thought, but nothing changed – Seraphim Apr 19 '22 at 11:48
@Seraphim works for me - see the [repro](https://dotnetfiddle.net/s0PwbB) – Guru Stron Apr 19 '22 at 11:56

Deserialize Json string with child objects

2 Answers2