.NET C# JsonConvert.DeserializeObject an Array

Question

I'm trying to deserialize an Object Array from an API service.

The data from the API has the following form:

{
"id": "9286",
"nome": "Bairro Novo",
"num_lotes": "312",
"num_quadras": "9",
"plots_id": "159351",
"geo_data": [
  {
    "loteamentos_id": "9286",
    "G": "-7.27087569384820000000",
    "K": "-34.90980863571200000000",
    "index": "0",
    "code": "V"
  },
  {
    "loteamentos_id": "9286",
    "G": "-7.27234968660550000000",
    "K": "-34.90971207618700000000",
    "index": "1",
    "code": "V"
  },
  {
    "loteamentos_id": "9286",
    "G": "-7.27317448188540000000",
    "K": "-34.90458905696900000000",
    "index": "2",
    "code": "V"
  },
  {
    "loteamentos_id": "9286",
    "G": "-7.27176434710060000000",
    "K": "-34.90472316741900000000",
    "index": "3",
    "code": "V"
  },
  {
    "loteamentos_id": "9286",
    "G": "-7.27202508786680000000",
    "K": "-34.90719884634000000000",
    "index": "15",
    "code": "C"
  }
]
  },

The class Loteamento:

public class Loteamento {

    [JsonProperty("id")]
    public string id { get; set; }

    [JsonProperty("nome")]
    public string nome { get; set; }

    [JsonProperty("num_lotes")]
    public string num_lotes { get; set; }

    [JsonProperty("num_quadras")]
    public string num_quadras { get; set; }

    [JsonProperty("plots_id")]
    public string plots_id { get; set; }

    [JsonProperty("geo_data")]
    public List<GeoData> geo_data { get; set; }

}

And the class GeoData:

 public class GeoData {

    [JsonProperty("loteamentos_id")]
    public string loteamentos_id { get; set; }

    [JsonProperty("G")]
    public string G { get; set; }

    [JsonProperty("K")]
    public string K { get; set; }

    [JsonProperty("index")]
    public string index { get; set; }

    [JsonProperty("code")]
    public string code { get; set; }

}

The question is that I get an error and do not know how to get an Array.

In my code I have:

List<Loteamento>[] loteamentos = null;
loteamentos = JsonConvert.DeserializeObject<List<Loteamento>>(dataObj.Result);

What's wrong?

Also, why are yo trying to assign a list to a array of lists? — Patrick Hofman
– Patrick Hofman, Commented Jun 13, 2016 at 10:00
@PatrickHofman Upsss! You are right. That was the problem! Thanks. — Apalabrados
– Apalabrados, Commented Jun 13, 2016 at 10:06

Richard Irons · Accepted Answer · 2016-06-13 10:05:07Z

1

List<Loteamento>[] loteamentos = null;
loteamentos = JsonConvert.DeserializeObject<List<Loteamento>>(dataObj.Result);

Your first line declares loteamentos as an array, where each cell in the array is a List<Loteamento>. So this variable is set up to hold multiple instances of the type List<Loteamento>.

Your second line then deserialises a single instance of List<Loteamento> and then tries to assign this into the loteamentos variable. The variable is unsuitable as it is an array of lists, not just a list.

I suspect it may work if you simply remove the [] from your first line.

answered Jun 13, 2016 at 10:05

Richard Irons

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Comments

Cetin Basoz · Accepted Answer · 2016-06-13 10:15:19Z

Using Newtonsoft Json.Net you can deserialize it like this:

void Main()
{
    string json = @"{
        ""id"": ""9286"",
""nome"": ""Bairro Novo"",
""num_lotes"": ""312"",
""num_quadras"": ""9"",
""plots_id"": ""159351"",
""geo_data"": [
  {
    ""loteamentos_id"": ""9286"",
    ""G"": ""-7.27087569384820000000"",
    ""K"": ""-34.90980863571200000000"",
    ""index"": ""0"",
    ""code"": ""V""
  },
  {
    ""loteamentos_id"": ""9286"",
    ""G"": ""-7.27234968660550000000"",
    ""K"": ""-34.90971207618700000000"",
    ""index"": ""1"",
    ""code"": ""V""
  },
  {
    ""loteamentos_id"": ""9286"",
    ""G"": ""-7.27317448188540000000"",
    ""K"": ""-34.90458905696900000000"",
    ""index"": ""2"",
    ""code"": ""V""
  },
  {
    ""loteamentos_id"": ""9286"",
    ""G"": ""-7.27176434710060000000"",
    ""K"": ""-34.90472316741900000000"",
    ""index"": ""3"",
    ""code"": ""V""
  },
  {
    ""loteamentos_id"": ""9286"",
    ""G"": ""-7.27202508786680000000"",
    ""K"": ""-34.90719884634000000000"",
    ""index"": ""15"",
    ""code"": ""C""
  }
]
  }";

 var result = JsonConvert.DeserializeObject<RootObject>(json);
}

public class GeoData
{
    public string loteamentos_id { get; set; }
    public string G { get; set; }
    public string K { get; set; }
    public string index { get; set; }
    public string code { get; set; }
}

public class RootObject
{
    public string id { get; set; }
    public string nome { get; set; }
    public string num_lotes { get; set; }
    public string num_quadras { get; set; }
    public string plots_id { get; set; }
    public List<GeoData> geo_data { get; set; }
}

Note: Classes are created from sample Json on http://json2csharp.com

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