Order of properties get messed up when serialized by JSON.NET

Question

In my POCO objects, I often inherit from other POCO objects. When I serialize a POCO object using JSON.NET, the order of properties gets all messed up.

Say, I have a Person class that looks like this:

public class Person
{
   public int Id {get; set;}
   public string FirstName {get; set;}
   public string LastName {get; set;}
}

Then I have an Employee class that inherits from Person class:

public class Employee : Person
{
   public int DepartmentId {get; set;}
   public string Title {get; set;}
}

When I serialize the Employee class, my JSON object looks like this:

{
   "departmentId": 123,
   "title": "Manager",
   "id": 1234567,
   "firstName": "John",
   "lastName": "Smith"
}

Two questions:

1. Does the order of my JSON object properties matter?
2. Even if the order of properties doesn't matter, how can I get the properties to be in correct order i.e. I'd like to see the Person class properties first, then the Employee class properties.

Thank you for your help.

Answer 1

1.) No, order doesn't matter.

2.) You can use the [JsonProperty(Order=x)] attribute to control the order:

public class Employee : Person
{
    [JsonProperty(Order = 1)]
    public int DepartmentId { get; set; }

    [JsonProperty(Order = 1)]
    public string Title { get; set; }
}

From a quick test, order defaults to 0, is sorted from low to high, and properties with the same value of Order are sorted in an arbitrary order.

Answer 2

Actually, since my Object was already a JObject, I Had to use the following solution:

public class SortedJObject : JObject
{
    public SortedJObject(JObject other)
    {
        var pairs = new List<KeyValuePair<string, JToken>>();
        foreach (var pair in other)
        {
            pairs.Add(pair);
        }
        pairs.OrderBy(p => p.Key).ForEach(pair => this[pair.Key] = pair.Value);
    }
}

and then use it like this:

string serializedObj = JsonConvert.SerializeObject(new SortedJObject(dataObject));