Return null when passing data exists in c#-CodePudding

I have a problem that I am confused. I have a piece of code that executes a Post API command like this:

{
    "chargeCriterias": null,
    "containerType": "Dry",
    "origin": {
        "code": "ABC"
    },
    "destination": {
        "code": "DYF"
    },
    "dateBegin": "2022-10-01T00:00:00",
    "dateEnd": "2022-11-30T23:59:59",
    "ratesFetcher": "XYZ",
}

I'm trying to write code to execute a command like this:

public class DataModel
{
    public LocationModelBase origin { get; set; }
    public LocationModelBase destination { get; set; }
    public string dateBegin { get; set; }
    public string dateEnd { get; set; }
    public string chargeCriterias { get; set; }
    public string containerType { get; set; }
    public string ratesFetcher { get; set; }
}

public class LocationModelBase
{
    public Int32 locationId { get; set; }
    public string code { get; set; }
}


var addGetdata = new DataModel();
{
    addGetdata.origin.code = "ABC";
    addGetdata.destination.code = "DYF";
    addGetdata.dateBegin = "2022-10-01T00:00:00";
    addGetdata.dateEnd = "2022-11-30T23:59:59";
    addGetdata.chargeCriterias = null;
    addGetdata.containerType = "Dry";
    addGetdata.ratesFetcher = "SSSS";
}

However I get the error: 'Object reference not set to an instance of an object.'.

I have checked the place value: addGetdata.origin and it says null. However I tried the ways but still didn't solve the problem. Where did I go wrong?

Looking forward to anyone's help or suggestions. Thank you

CodePudding user response：

You are not creating an instance of the LocationModelBase on either the origin or destination so they default to null.

Either create them before you assign...

addGetdata.origin = new LocationModelBase();
addGetdata.origin.code = "ABC";
addGetdata.destination = new LocationModelBase();
addGetdata.destination.code = "DYF";

Or alternatively, create them as part of the construction of the class...

public LocationModelBase origin { get; set; } = new LocationModelBase();
public LocationModelBase destination { get; set; } = new LocationModelBase();

CodePudding user response：

When initializing your DataModel class, you need to need initialize the other classes used for your model.

public LocationModelBase origin { get; set; }
public LocationModelBase destination { get; set; }

These properties have a type of another class and must be initialized before assigning values to that class' properties.

var addGetdata = new DataModel
{
    origin = new LocationModelBase
    {
        code = "ABC"
    }
    destination new LocationModelBase
    {
        code = "DYF"
    }
    ...
}