C# flattening json structure

JObject jsonObject=JObject.Parse(theJsonString);
IEnumerable<JToken> jTokens = jsonObject.Descendants().Where(p => p.Count() == 0);
Dictionary<string, string> results = jTokens.Aggregate(new Dictionary<string, string>(), (properties, jToken) =>
                    {
                        properties.Add(jToken.Path, jToken.ToString());
                        return properties;
                    });

I had the same requirement of flattening a nested json structure to a dictionary object. Found the solution here.

You can use https://github.com/jsonfx/jsonfx to deserialize json into a dynamic object. Then use the ExpandoObject to get what you want.

public Class1()
        {
            string json = @"{
                                ""name"": ""test"",
                                ""father"": {
                                     ""name"": ""test2"",
                                     ""age"": 13,
                                     ""dog"": {
                                         ""color"": ""brown""
                                     }
                                }
                            }";

            var reader = new JsonFx.Json.JsonReader();
            dynamic output = reader.Read(json);
            Dictionary<string, object> dict = new Dictionary<string, object>();

            GenerateDictionary((System.Dynamic.ExpandoObject) output, dict, "");
        }

        private void GenerateDictionary(System.Dynamic.ExpandoObject output, Dictionary<string, object> dict, string parent)
        {
            foreach (var v in output)
            {
                string key = parent + v.Key;
                object o = v.Value;

                if (o.GetType() == typeof(System.Dynamic.ExpandoObject))
                {
                    GenerateDictionary((System.Dynamic.ExpandoObject)o, dict, key + ".");
                }
                else
                {
                    if (!dict.ContainsKey(key))
                    {
                        dict.Add(key, o);
                    }
                }
            }
        }

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<string, JsonElement> 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<string, JsonElement> 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;
    }