JSON.NET - Merge Json #json

merge-json.cs

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

namespace CommonLib
{
    public class JsonHelper
    {
        /*
        string json = JsonHelper.MergeJson(null, @"{
    'FirstName': 'John',
    'LastName': 'Smith',
    'Enabled': false,
    'Roles': [ 'User' ]
}", "User");

            string mergedJson = JsonHelper.MergeJson(json, @"{
    'Foo': 'Bar',
    'Count': 42,
    'Success': true,
}", "Misc", Formatting.Indented);

        ...returns:

        {
          "User": {
            "FirstName": "John",
            "LastName": "Smith",
            "Enabled": false,
            "Roles": [
              "User"
            ]
          },
          "Misc": {
            "Foo": "Bar",
            "Count": 42,
            "Success": true
          }
        }
        */

        public static string MergeJson(string origJson, string newJson,
            string newJsonRootKey, Formatting formatting = Formatting.None)
        {
            JObject newObj = JObject.Parse(newJson);

            if (newJsonRootKey != null)
            {
                // wrap new object in the specified root key
                newObj = new JObject
                {
                    [newJsonRootKey] = newObj,
                };
            }

            if (origJson == null)
            {
                return newObj.ToString(formatting);
            }
            else
            {
                // merge

                JObject oldObj = JObject.Parse(origJson);

                oldObj.Merge(newObj, new JsonMergeSettings
                {
                    MergeArrayHandling = MergeArrayHandling.Replace,
                    MergeNullValueHandling = MergeNullValueHandling.Merge,
                });

                return oldObj.ToString(formatting);
            }
        }

        // https://www.newtonsoft.com/json/help/html/SelectToken.htm
        // https://www.newtonsoft.com/json/help/html/QueryJsonSelectTokenJsonPath.htm
        // string firstName = JsonHelper.GetJObjectProperty<string>(jObject, "$.User.FirstName");
        // int? count = JsonHelper.GetJObjectProperty<int?>(jObject, "$.Misc.Count");
        public static T GetJObjectProperty<T>(JObject obj, string jpathExpression)
        {
            JToken jToken = obj.SelectToken(jpathExpression);
            if (jToken == null)
                return default(T);
            T t = jToken.ToObject<T>();
            return t;
        }
    }
}