Convert DataTable to JSON with key per row

Question

I thought the following would be a pretty common task and assumed there would be an easy solution for it, but i can't find one.

If I have a datatable in the following structure.

ID  Name    Active
ID1 John    TRUE
ID2 Bill    FALSE

I would like to serialize it as a JSON object where the ID column is a node in the JSON object like:

[
    {
        "ID1": {
            "Name": "John",
            "Active": "True"
        },
        "ID2": {
            "Name": "Bill",
            "Active": "False"
        }
    }
]

I looked into JSON.NET but could not get it to work. Edit: I'm using C#

Answer 1

This is quite simple with JSON.NET. Just convert your data table into the equivalent dictionary of dictionaries:

public Dictionary<string, Dictionary<string, object>> DatatableToDictionary(DataTable dt, string id)
{
    var cols = dt.Columns.Cast<DataColumn>().Where(c => c.ColumnName != id);
    return dt.Rows.Cast<DataRow>()
             .ToDictionary(r => r[id].ToString(), 
                           r => cols.ToDictionary(c => c.ColumnName, c => r[c.ColumnName]));
}

Then call:

JsonConvert.SerializeObject(DatatableToDictionary(dt, "ID"), Newtonsoft.Json.Formatting.Indented);

Here's the full test:

var dt = new DataTable("MyTable");
dt.Columns.Add("ID");
dt.Columns.Add("Name");
dt.Columns.Add("Active");

dt.LoadDataRow(new[] {"ID1", "John", "True"}, true);
dt.LoadDataRow(new[] {"ID2", "Bill", "False"}, true);

JsonConvert.SerializeObject(DatatableToDictionary(dt, "ID"));

And the result:

{
  "ID1": {
    "Name": "John",
    "Active": "True"
  },
  "ID2": {
    "Name": "Bill",
    "Active": "False"
  }
}

Answer 2

Using JSON.NET (Newtonsoft.Json.Linq)

var obj = new JObject(
    dataTable.Rows.Cast<DataRow>()
         .Select(r => new JProperty(r["ID"].ToString(),
                 new JObject(
                     new JProperty("Name", r["Name"].ToString()),
                     new JProperty("Active", r["Active"].ToString())
                 )
             ))
);

// Convert the JObject to a JSON string
var json = obj.ToString();