C# - Class.models.modelname.list.get returned null when using List.Add

Question

I built a class:

public partial class SvcCodes
{
    public List<SvcCodeReport> Report { get; set; }
    public List<SvcCodesCheck> TestList { get; set; }
}

It uses this class:

public partial class SvcCodeReport
{
    public List<Dictionary<string, object>> ProgResults { get; set; }
    public IEnumerable<ExtraData> ExtraData { get; set; }
}

In the controller, data is pulled from two sources and assigned to the SvcCodeReport class:

var model = new SvcCodeReport()
{
  ProgResults = tasks,
  ExtraData = _context.ExtraData.Where(h => h.ServiceCode == Int32.Parse(id)
};

Then the model variable is added to the Report class:

check.Report.Add(model);

But when I run the program, I get a null object error and a line that says:

LRProgReport.Models.SvcCodes.Report.get returned null

Is this error saying that Report is null BEFORE the add or after?

If before, why is that an issue? If after, why is the model variable not being added to the list?

Emre Kabaoglu · Accepted Answer · 2018-01-22 18:23:11Z

11

You should initialize the Report list first and you can do it in the SvcCodes constructor;

public partial class SvcCodes
{
    public List<SvcCodeReport> Report { get; set; }
    public List<SvcCodesCheck> TestList { get; set; }

    public SvcCodes()
    {
        Report = new List<SvcCodeReport>();
    }
}

answered Jan 22, 2018 at 18:23

Emre Kabaoglu

13.2k4 gold badges27 silver badges48 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Mighty Ferengi Over a year ago

Excellent! that's what was missing. Thanks!

pm100 · Accepted Answer · 2018-01-22 18:22:01Z

1

I suspect you are falling fowl of Linq's deferred execution model. When you do x.Where() etc the code is not run then. It is only run when you finally force the data to be used. Try this instead

var model = new SvcCodeReport()
{
  ProgResults = tasks,
  ExtraData = _context.ExtraData.Where(h => h.ServiceCode == Int32.Parse(id).ToList();
};

This will force _context.ExtraData to be evaluated right there

answered Jan 22, 2018 at 18:22

pm100

50.6k25 gold badges95 silver badges158 bronze badges

1 Comment

Markiian Benovskyi Over a year ago

This is true, but not the OP problem

Collectives™ on Stack Overflow

C# - Class.models.modelname.list.get returned null when using List.Add

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related