Convert JSON to DataTable returns empty result in c#

Question

I am trying to convert my json data to data table. Followed all approaches from this post and also all suggested links all over stackoverflow, tried many ways but still no result.

My method looks like:

    public static async Task GetManagements()
    {
        Console.WriteLine("Getting managements");

        using var client = new HttpClient();

        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", 
        await Token.GetToken());

        HttpResponseMessage response = await client.GetAsync(LibvirtUrls.managementUrl);
        HttpContent content = response.Content;

        Console.WriteLine("Response Status Code: " + (int)response.StatusCode);
        string result = await content.ReadAsStringAsync();
        var json = Helpers.FormatJson(result);
        Console.WriteLine("json");
        Console.WriteLine(result); // for testing
        Console.WriteLine(new string('-',35));
        Console.WriteLine("formatted");
        Console.WriteLine(json); // for testing
        // I used both result and json (formatted and not formatted one)
        Console.WriteLine(new string('-',35));
        List<NetworkDto> networkList = 
        JsonConvert.DeserializeObject<List<NetworkDto>>(json);
        Console.WriteLine("table view");
        var ss = networkList.ToDataTable<NetworkDto>();
        Console.WriteLine(ss);
    }

Sample json is after executing method:

Getting managements as json
Response Status Code: 200
json
[{"id":1,"netMask":22,"gateway":"10.19.0.1","jenkinsUrl":"http://10.19.0.20:31000","bridge":"br0","ipRange":"10.19.0.1-10.19.3.254"},{"id":11,"netMask":22,"gateway":"10.23.0.1","jenkinsUrl":"http://10.12.3.12:33355","bridge":"br2","ipRange":"10.23.0.4-10.23.0.20"}]
------------------------------------------
formatted
[
    {
        "id":1,
        "netMask":22,
        "gateway":"10.19.0.1",
        "jenkinsUrl":"http://10.19.0.20:31000",
        "bridge":"br0",
        "ipRange":"10.19.0.1-10.19.3.254"
    },
    {
        "id":11,
        "netMask":22,
        "gateway":"10.23.0.1",
        "jenkinsUrl":"http://10.12.3.12:33355",
        "bridge":"br2",
        "ipRange":"10.23.0.4-10.23.0.20"
    }
]
------------------------------------------------
table view

Tried also with class:

    public class NetworkDto
    {
        public int Id { get; set; }
        public int NetMask { get; set; }
        public string Gateway { get; set; }
        public string JenkinsUrl { get; set; }
        public string Bridge { get; set; }
        public string IpRange { get; set; }
    }

Extension method I am using for converting json to data table:

    public static DataTable ToDataTable<T>(this IList<T> data)
    {
        PropertyDescriptorCollection props =
            TypeDescriptor.GetProperties(typeof(T));
        DataTable table = new DataTable();
        for(int i = 0 ; i < props.Count ; i++)
        {
            PropertyDescriptor prop = props[i];
            table.Columns.Add(prop.Name, prop.PropertyType);
        }
        object[] values = new object[props.Count];
        foreach (T item in data)
        {
            for (int i = 0; i < values.Length; i++)
            {
                values[i] = props[i].GetValue(item);
            }
            table.Rows.Add(values);
        }
        return table;        
    }

Why convert it to a DataTable in the first place? Why not define an class to represent this information, then deserialize to a `List`? — mason, Feb 27 '20 at 14:29
Edit your question, include your attempt at deserializing to a `List` and show the definition of that class. — mason, Feb 27 '20 at 14:30
Are you sure, that `Console.WriteLine(dt);` prints the content of the table? I tested with your json and I see the data table filled (in debugger) but not on console. — H.G. Sandhagen, Feb 27 '20 at 14:50
I am able print json ugly one and formatted one, but why it is failing with data table no idea — Arzu Suleymanov, Feb 27 '20 at 14:51
@H.G.Sandhagen I edited my question decription also tried with List of NetworkDto class — Arzu Suleymanov, Feb 27 '20 at 14:52
What is the result of `JsonConvert.DeserializeObject>(json);`? — mason, Feb 27 '20 at 14:53
@mason **System.Collections.Generic.List`1[TaikunCLI.NetworkDto]** — Arzu Suleymanov, Feb 27 '20 at 14:54
@ArzuSuleymanov That's exactly what you want it to be! It works. So what's the problem? — mason, Feb 27 '20 at 15:15

score 1 · Answer 1 · answered Feb 27 '20 at 14:59

I checked your code:

        static void Main() {
        string json = "[{\"id\":1,\"netMask\":22,\"gateway\":\"10.19.0.1\",\"jenkinsUrl\":\"http://10.19.0.20:31000\",\"bridge\":\"br0\",\"ipRange\":\"10.19.0.1-10.19.3.254\"},{\"id\":11,\"netMask\":22,\"gateway\":\"10.23.0.1\",\"jenkinsUrl\":\"http://10.12.3.12:33355\",\"bridge\":\"br2\",\"ipRange\":\"10.23.0.4-10.23.0.20\"}]";

        System.Data.DataTable dt = (System.Data.DataTable)JsonConvert.DeserializeObject(json, (typeof(System.Data.DataTable)));
        Console.WriteLine(dt);

        for (int i = 0; i < dt.Columns.Count; i++) {
            Console.Write(dt.Columns[i] + " | ");
        }
        Console.WriteLine();
        for (int j = 0; j < dt.Rows.Count; j++) {

            for (int i = 0; i < dt.Columns.Count; i++) {
                Console.Write(dt.Rows[j].ItemArray[i] + " | ");
            }
            Console.WriteLine();

        }
    }

Output:

1 | 22 | 10.19.0.1 | http://10.19.0.20:31000 | br0 | 10.19.0.1-10.19.3.254 |

11 | 22 | 10.23.0.1 | http://10.12.3.12:33355 | br2 | 10.23.0.4-10.23.0.20 |

Seems, that the data table is filled

@ArzuSuleymanov Don't use a DataTable! They're far harder to work with than a nice strongly typed object. — mason, Feb 27 '20 at 15:14
@mason could you recommend any another alternative, right now I have 3 scenario, show as json,yaml and table (for table I chose DataTable). But if you have other suggestion. Please propose — Arzu Suleymanov, Feb 27 '20 at 15:16

score 1 · Accepted Answer · answered Feb 27 '20 at 15:22

Deserializing from JSON to a list of custom objects is trivial:

List<NetworkDto> networkList = JsonConvert.DeserializeObject<List<NetworkDto>>(json);

And that's it! Now your networkList variable is a list of NetworkDto objects. You can write them all out to the console if you want to verify they're in there:

foreach(var network in networkList)
(
    Console.WriteLine($"Network Id {network.Id}");
)

Convert JSON to DataTable returns empty result in c#

2 Answers2