Json.net append json file

Question

I have the following code which uses Json.net:

class HistorianRecord
{
    public string tagname { get; set; }
    public string engunits { get; set; }
    public string value { get; set; }
    public string quality { get; set; }
    public DateTime timestamp { get; set; }
}

private static void createJSONFile(DataTable dt)
{
    var HistorianData = new List<HistorianRecord>();

    foreach(DataRow row in dt.Rows)
    {
        HistorianData.Add(new HistorianRecord()
        {
            tagname = row["tagname"].ToString(),
            engunits = row["engunits"].ToString(),
            value =  row["value"].ToString(),
            quality = row["quality"].ToString(),
            timestamp = DateTime.Parse(row["timestamp"].ToString())
        });
    }

    var serializer = new JavaScriptSerializer();
    var serializedResult = serializer.Serialize(HistorianData);
    var deserializedResult = serializer.Deserialize<List<HistorianRecord>>(serializedResult);

    File.WriteAllText(folderPath + fileName, JsonConvert.SerializeObject(deserializedResult));
}

Which produces the following JSON file, which I have shortened for this post as the are > 1000 rows in the datatable:

[
  {
    "tagname": "mytag1",
    "engunits": "",
    "value": "2",
    "quality": "Good NonSpecific",
    "timestamp": "2018-12-13T10:45:05Z"
  },
  {
    "tagname": "myTag2",
    "engunits": "",
    "value": "0",
    "quality": "Good NonSpecific",
    "timestamp": "2018-12-13T10:45:00Z"
  }
]

I would like to amend my code to so I can add some items at the beginning of the JSON file so it looks more like this:

[
  {
    "name": "ARandomName",
    "content": [
      {
        "tagname": "mytag1",
        "engunits": "",
        "value": "2",
        "quality": "Good NonSpecific",
        "timestamp": "2018-12-13T10:45:05Z"
      },
      {
        "tagname": "myTag2",
        "engunits": "",
        "value": "0",
        "quality": "Good NonSpecific",
        "timestamp": "2018-12-13T10:45:00Z"
      }
    ]
  }
]

This is so I can create some documents for a test MongoDB installation that I am investigating so all help is appreciated.

Brian Rogers · Accepted Answer · 2018-12-13 16:20:57Z

1

You simply can wrap your deserialized list of HistorianRecords in an anonymous object and reserialize it:

var anon = new 
{
    name = "ARandomName",
    content = deserializedResult 
};

string newJson = JsonConvert.SerializeObject(anon, Formatting.Indented);

Fiddle: https://dotnetfiddle.net/6kSvxS

edited Dec 13, 2018 at 16:20

answered Dec 13, 2018 at 16:12

Brian Rogers

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