C# flattening json structure

Question

I have a json-object in C# (represented as a Newtonsoft.Json.Linq.JObject object) and I need to flatten it to a dictionary. Let me show you an example of what I mean:

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Answer 1

As of .NET Core 3.0 JsonDocument is a way (Json.NET is not needed). I'm sure this will get easier.

using System.Linq;
using System.Text.Json;
(...)


public static Dictionary GetFlat(string json)
{
    IEnumerable<(string Path, JsonProperty P)> GetLeaves(string path, JsonProperty p)
        => p.Value.ValueKind != JsonValueKind.Object
            ? new[] { (Path: path == null ? p.Name : path + "." + p.Name, p) }
            : p.Value.EnumerateObject() .SelectMany(child => GetLeaves(path == null ? p.Name : path + "." + p.Name, child));

    using (JsonDocument document = JsonDocument.Parse(json)) // Optional JsonDocumentOptions options
        return document.RootElement.EnumerateObject()
            .SelectMany(p => GetLeaves(null, p))
            .ToDictionary(k => k.Path, v => v.P.Value.Clone()); //Clone so that we can use the values outside of using
}

A more expressive version is shown below.

Test

using System.Linq;
using System.Text.Json;
(...)

var json = @"{
    ""name"": ""test"",
    ""father"": {
            ""name"": ""test2"", 
         ""age"": 13,
         ""dog"": {
                ""color"": ""brown""
         }
        }
    }";

var d = GetFlat(json);
var options2 = new JsonSerializerOptions { WriteIndented = true };
Console.WriteLine(JsonSerializer.Serialize(d, options2));

Output

{
  "name": "test",
  "father.name": "test2",
  "father.age": 13,
  "father.dog.color": "brown"
}

More expressive version

using System.Linq;
using System.Text.Json;
(...)

static Dictionary GetFlat(string json)
    {
        using (JsonDocument document = JsonDocument.Parse(json))
        {
            return document.RootElement.EnumerateObject()
                .SelectMany(p => GetLeaves(null, p))
                .ToDictionary(k => k.Path, v => v.P.Value.Clone()); //Clone so that we can use the values outside of using
        }
    }


    static IEnumerable<(string Path, JsonProperty P)> GetLeaves(string path, JsonProperty p)
    {
        path = (path == null) ? p.Name : path + "." + p.Name;
        if (p.Value.ValueKind != JsonValueKind.Object)
            yield return (Path: path, P: p);
        else
            foreach (JsonProperty child in p.Value.EnumerateObject())
                foreach (var leaf in GetLeaves(path, child))
                    yield return leaf;
    }