How to Deserialize a JSON Array from Web API in UPW C#?

Question

I want to connect to bitbay web api, get data JSON from there and save it to a file. My JSON looks like that:

{
  "status": "Ok",
  "items": [
    {
      "id": "737a2935-84c9-11ea-8cdc-0242ac11000e",
      "t": "1587581134890",
      "a": "0.00926098",
      "r": "29999",
      "ty": "Buy"
    },
    {
      "id": "6c4474fa-84c9-11ea-8cdc-0242ac11000e",
      "t": "1587581122794",
      "a": "0.02475367",
      "r": "29999",
      "ty": "Buy"
    }
  ]
}

I want to get t,a,r and ty from it. I've got code:

public class TradeModel
    {
        public decimal R { get; set; }
        public decimal A { get; set; }
        public string Ty { get; set; }
        public DateTime T { get; set; }
    }

public class TradeItemModel
    {
        public TradeModel Items { get; set; }
    }

public class TradeProcessor
    {
        public static async Task<TradeModel> LoadTrades( int limit = 1 )
        {
            string url = "";

            if (limit <= 300)
            {
                url = $"https://api.bitbay.net/rest/trading/transactions/BTC-PLN?limit={ limit }";
            }
            else
            {

            }

            using (HttpResponseMessage response = await ApiHelper.ApiClient.GetAsync(url))
            {
                if (response.IsSuccessStatusCode)
                {
                    TradeItemModel trade = await response.Content.ReadAsAsync<TradeItemModel>();

                    return trade.Items;       
                }
                else
                {
                    throw new Exception(response.ReasonPhrase);
                }
            }
        }
    }

After I run this code I gets an Exception: Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'DemoLibrary.TradeModel' because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly. To fix this error either change the JSON to a JSON object (e.g. {"name":"value"}) or change the deserialized type to an array or a type that implements a collection interface (e.g. ICollection, IList) like List that can be deserialized from a JSON array. JsonArrayAttribute can also be added to the type to force it to deserialize from a JSON array. Path 'items', line 1, position 24.”

Mohammed Sajid · Accepted Answer · 2020-04-22 19:34:16Z

1

The Item in TradeItemModel class should be a collection TradeModel[] or List<TradeModel>, and you can also add Status to check it if is OK or KO:

public class TradeItemModel
{
    public string Status { get; set; }
    public List<TradeModel> Items { get; set; }
}

You must change also the method signature to:

public static async Task<List<TradeModel>> LoadTrades( int limit = 1 )

I hope this helps you out.

edited Apr 22, 2020 at 19:34

answered Apr 22, 2020 at 19:29

Mohammed Sajid

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4 Comments

Kamil Over a year ago

Thank you :). I've got one more question how can I get an element in that list for example I have button and method Click where I create variable var tradeInfo = await TradeProcessor.LoadTrades(); and I want to display R of trademodel class in my textblock which name is price?

Mohammed Sajid Over a year ago

you're welcome, you have a collection with two TradeModel, so you want the first R or sum of R? First R value : trade.Items.First().R or sum : trade.Items.Sum(x=>x.R). if the first issue is resolved by my answer, can you please mark the answer like accepted?

Kamil Over a year ago

Yes no problem, I'll give you +1 if I can. That's all for me

Mohammed Sajid Over a year ago

yes you can now, you need just 15 reputation to upvote. so for getting the R my response works? by using sum or first functions?

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