Your basic difficulty here is that JSON has two types of container: an object, and an array. From the standard:
-
An array is an ordered collection of values. An array begins with
[
(left bracket) and ends with]
(right bracket). Values are separated by,
(comma). -
An object is an unordered set of name/value pairs. An object begins with
{
(left brace) and ends with}
(right brace).
To force a collection’s properties to be serialized, mark it with [JsonObject]
:
[JsonObject]
public class TestResultListModel : List<TestResultModel>
{
public int TotalTestCases { get { return base.Count; } }
public int TotalSuccessful { get { return base.FindAll(t => t.Successful).Count; } }
}
Of course, if you do this, the items will not be serialized, because a JSON container can have properties, or items — but not both. If you want both, you will need to add a synthetic array property to hold the items — which can be private if you want.
[JsonObject]
will also cause base class properties such as Capacity
to be serialized, which you likely do not want. To suppress base class properties, use MemberSerialization.OptIn
. Thus your final class should look something like:
[JsonObject(MemberSerialization = MemberSerialization.OptIn)]
public class TestResultListModel : List<TestResultModel>
{
[JsonProperty]
public int TotalTestCases { get { return base.Count; } }
[JsonProperty]
// Using Enumerable.Count() is more memory efficient than List.FindAll()
public int TotalSuccessful { get { return this.Count(t => t.Successful); } }
[JsonProperty]
TestResultModel[] Items
{
get
{
return this.ToArray();
}
set
{
if (value != null)
this.AddRange(value);
}
}
}
This gives JSON that looks like:
{ "TotalTestCases": 4, "TotalSuccessful": 2, "Items": [ { "Successful": false, "ErrorMessage": "STRING" }, { "Successful": true, "ErrorMessage": "STRING" }, { "Successful": false, "ErrorMessage": "STRING" }, { "Successful": true, "ErrorMessage": "STRING" } ] }
It is possibly more work than it’s worth, since these properties could be reconstructed easily on the client side. (The question Why not inherit from List? suggests avoiding this sort of design.)