JSON add node to an existing JObject

Question

I am trying to add a new node to an existing JSON JObject, but when I add it does not format correctly. It adds quotes around the entire node, and \ are put in place.

Background: I am loading a JSON file, doing some logic then adding a node back in. Figured I can do it like this:

mainJson.Add("NewNode", JsonConvert.SerializeObject(MyObject));
File.WriteAllText("myfile.json", mainJson.ToString());

Problem is that this is the result:

{
"JSONFile": [
  {
    "More": "Nodes",
    "InThe": "File"
  }
],
"Customers": "{\"FirstName\":\"Mike\",\"LastName\":\"Smith\"},{\"FirstName\":\"Jane\",\"LastName\":\"Doe\"}",
}

I know that my JsonConvert.SerializeObject(MyObject) is working if I do this:

string json = JsonConvert.SerializeObject(MyObject);
File.WriteAllText("myfile2.json" json);

The result is this:

[
  {
    "FirstName": "Mike",
    "LastName": "Smith"
  },
  {
    "FirstName": "Jane",
    "LastName": "Doe"
  }
]

What am I missing?

edit: Following @Swagata Prateek comment of;

mainJson.Add("Customers",JObject.FromObject(MyObject));

An unhandled exception of type 'System.ArgumentException' occurred in Newtonsoft.Json.dll

Additional information: Object serialized to Array. JObject instance expected.

I should note that MyObject is actual ObservableCollection if that makes a difference

When you invoke JsonConvert.SerializeObject(MyObject) , MyObject here is serialized as a string, thus the NewNode here is presenting itself as a string quoted. :) — Swagata Prateek
– Swagata Prateek, Commented Sep 6, 2016 at 15:07

Swagata Prateek · Accepted Answer · 2016-09-06 17:23:39Z

8

Could you kindly try with this?

mainJson.Add("NewNode", JObject.FromObject(MyObject));
File.WriteAllText("myfile.json", mainJson.ToString());

When you are doing JsonConvert.SerializeObject(MyObject) it serializes MyObject and in the process you get a string out of it.

When you assign mainJson.Add("NewNode", JsonConvert.SerializeObject(MyObject)); you're assigning a string to NewNode. Thus you get a quoted string that represents serialized MyObject

Update:

JArray.FromObject is the method you'd want to look for if you want to convert your collection to a JArray. In that case the segment would look something like

mainJson.Add("NewNode", JArray.FromObject(obsColl));
File.WriteAllText("myfile.json", mainJson.ToString());

edited Sep 6, 2016 at 17:23

answered Sep 6, 2016 at 15:10

Swagata Prateek

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2 Comments

Xaphann Over a year ago

A man chooses, a slave obeys! anyways please look at the above edit. This is returning an error.

Swagata Prateek Over a year ago

Ooops. Sorry dude. Didnt know that was a collection. Hold on. Not sure i can type code segment properly through a phone

Nagesh Ajab · Accepted Answer · 2020-10-06 10:54:59Z

using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            JObject tempvar= JObject.Parse(@"{
  'CPU': 'Intel',
  'Drives': [
    'DVD read/writer',
    '500 gigabyte hard drive'
  ]
}");
            string cpu = (string)tempvar["CPU"];          // Intel
            string firstDrive = (string)tempvar["Drives"][0];   // DVD read/writer
IList<string> allDrives = tempvar["Drives"].Select(t => (string)t).ToList();
            // DVD read/writer
            // 500 gigabyte hard drive

            tempvar["Drives"][0].AddAfterSelf("new node");
//tempvar json with new node
        }
    }
}

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