JSON deserialized object returns null

Question

Source Code - Main class

        string responseBody = await response.Content.ReadAsStringAsync();

        status.result deserializeObject = JsonConvert.DeserializeObject<status.result>(responseBody);

        Debug.WriteLine(deserializeObject.SafeGasPrice.ToString());

Source Code - JSON Class

    public class status
    {
        public class result
        {
            [JsonProperty(PropertyName = "SafeGasPrice")]
            public int SafeGasPrice { get; set; }

            [JsonProperty(PropertyName = "ProposeGasPrice")]
            public int ProposeGasPrice { get; set; }

            [JsonProperty(PropertyName = "FastGasPrice")]
            public int FastGasPrice { get; set; }
        }
    }

Output

{"status":"1","message":"OK","result":{"LastBlock":"14296250","SafeGasPrice":"96","ProposeGasPrice":"96","FastGasPrice":"97","suggestBaseFee":"95.407119606","gasUsedRatio":"0.174721033333333,0.523179548504219,0.056945596868572,0.999939743363228,0.953861217484817"}}

0

Problem

I don't currently understand why a null is output, my guess is that I have implemented the json deserialization classes incorrectly.

Answer 1

Your data model does not correspond to the JSON provided, it is missing a type corresponding to the outer {"result": { }} object:

{
   "status":"1",
   "message":"OK",
   "result":{
      // This inner object corresponds to your model.
      "LastBlock":"14296250",
      "SafeGasPrice":"96",
      "ProposeGasPrice":"96",
      "FastGasPrice":"97",
      "suggestBaseFee":"95.407119606",
      "gasUsedRatio":"0.174721033333333,0.523179548504219,0.056945596868572,0.999939743363228,0.953861217484817"
   }
}

To work around the problem, you need to introduce an outer, wrapper model. You could make an explicit one like so:

public class Root
{
    public string status { get; set; }
    public string message { get; set; }
    public Result result { get; set; }
}

public class Result
{
    [JsonProperty(PropertyName = "SafeGasPrice")]
    public int SafeGasPrice { get; set; }

    [JsonProperty(PropertyName = "ProposeGasPrice")]
    public int ProposeGasPrice { get; set; }

    [JsonProperty(PropertyName = "FastGasPrice")]
    public int FastGasPrice { get; set; }
}

And deserialize like so:

var deserializeObject = JsonConvert.DeserializeObject<Root>(responseBody)?.result;

Or, you could use an anonymous type for the root model like so:

var deserializeObject = JsonConvert.DeserializeAnonymousType(responseBody, new { result = default(Result) })?.result;

Either way you will now be able to successfully deserialize the inner, nested properties.

So what did you do wrong? In your question, you declare result as a nested type:

public class status
{
    public class result
    {
        [JsonProperty(PropertyName = "SafeGasPrice")]
        public int SafeGasPrice { get; set; }

        [JsonProperty(PropertyName = "ProposeGasPrice")]
        public int ProposeGasPrice { get; set; }

        [JsonProperty(PropertyName = "FastGasPrice")]
        public int FastGasPrice { get; set; }
    }
}

All this does is define a type result within the scope of another type status. It does not create a property named result within status. As there is no need for such nesting I recommend moving result out from inside status and renaming it Result to follow standard .NET naming conventions.

Demo fiddle here.