Return nested arrays in restful api with dotnet core 3.0

Question

I'm writing an api call in dotnet core 3.0 and trying to return several objects. I can return all the objects as long as the information in them is simple. But, when I have an array of objects (that also contain arrays) the result for that object is empty.

For example, in the following code, the first three items (a c# object, a list of strings and a string) all return values, but the list of chartdatasets is empty in the result of the call. It is populated when I step through the code on the server side.

Do I have to do something special to return an array of complex objects?

[HttpGet]
public ActionResult<List<Chart>> GetCharts()
{
    List<string> axisLabels = new List<string>() {"CLI","MC","MCAL","PAT","PTP","TP"};
    string chartTitle = "Outstanding AR by Fin Group";
    ReturnKey retKey = new ReturnKey() {AuthKey = "asdasdas", Message = "OK"};

    List<ChartDataSet> dataSetList = new List<ChartDataSet>();
    List<double> cData = new List<double>();
    cData.Add(37795.59);
    cData.Add(16839.71);
    cData.Add(144.89);
    cData.Add(90);
    cData.Add(216829.68);
    cData.Add(1764.52);
    List<string> cBg = new List<string>();
    dataSetList.Add(new ChartDataSet("Outstanding AR", cBg, cData));

    return Ok(new {retKey, axisLabels, chartTitle, dataSetList});
}

The result in postman looks like this.

{
    "retKey": {
        "authKey": "asdasdas",
        "message": "OK"
    },
    "axisLabels": [
        "CLI",
        "MC",
        "MCAL",
        "PAT",
        "PTP",
        "TP"
    ],
    "chartTitle": "Outstanding AR by Fin Group",
    "dataSetList": [
        {}
    ]
}

Answer 1

I did not post the definition of the ChartDataSet, but it turns out that is where the problem was. From a discussion with a colleague, we found that the ChartDataSet attributes were not encapsulated. After adding {get;set} to each attribute I wanted to return in the API, it seems to be working.

    [Serializable]
public class ChartDataSet {
    public string label {get;set;}
    public string backgroundColor {get;set;}
    public List<double> data {get;set;}

    public ChartDataSet(string lbl, string bgcolor, List<double> datavalue)
    {
        label = lbl;
        backgroundColor = bgcolor;
        data = datavalue;
    }
}