Add a new entry to the json file

I have a JSON file with the following format:

      "profiles": {
        "Profile1": {
          "name": "Nombre 1",
          "lastVersionId": "",
          "javaArgs": "-Xmx8G"
        "Profile2": {
          "name": "Nombre 2",
          "lastVersionId": "58.96.004",
          "javaArgs": "-Xmx8G"
      "selectedProfile": "Profile1"

I need to add a new profile, that is, add this entire block:

    "Profile3": {
      "name": "Nombre 3",
      "lastVersionId": "58.96.004",
      "javaArgs": "-Xmx8G"

I forgot to say that I don't know all the fields of JSON, therefore, I can't use classes to deserialize.

I have tried a thousand codes that I found in stackoverflow but most are for adding only individual fields or editing the values of existing fields. I am using Newtonsoft on

I would appreciate all the help possible.

1 answer

  • answered 2019-12-09 01:06 Jawad

    One way to add without using classes would be to create a JObject and insert that to the Profiles.

        dynamic jsonObject = JsonConvert.DeserializeObject(json);
        var profile3 = new JObject
            ["name"] = "Nombre 3",
            ["lastVersionID"] = "58.96.004",
            ["javaArgs"] = "-Xmx8G"
        jsonObject["profiles"]["Profile3"] = profile3;

    Since you mentioned, " I don't know all the fields of JSON", it becomes hard to use a method to instantiate a profile (like using a method to create same object each time but if its different, it will have to be manually created and inserted.

    EDIT: To remove an obj from inside elements, use Property and Remove(). If you want to include checking the null objects, use the ?.Remove().


    Edit 2: You can check if the Profile exists before updating as well.

    Console.WriteLine(jsonObject["profiles"]["Profile4"] != null);
    // output: