Object not set to an instance of an object when using Any()

Question

I have the following LINQ

OfferOrder pricedOfferOrder = OrderData.OfferOrder
  .Where(d => d.Question.Any(e => e.Price != null)).FirstOrDefault().Question);

It works fine but when Price of all Question are null it throws the following Exception:

Object reference not set to an instance of an object

My classes look like this:

public partial class OrderOrderData
{
    public OrderOrderDataOfferOrder[] OfferOrder{get;set}
}

public partial class OrderOrderDataOfferOrder
{
    public OrderOrderDataOfferOrderQuestion[] Question{get;set}
}

public partial class OrderOrderDataOfferOrderQuestion
{
    public OrderOrderDataOfferOrderQuestionPrice Price{get;set;}
}

How can I avoid this?

Christos · Accepted Answer · 2017-06-12T07:43:01.250

1

Provided that you are using C# 6, you could make use of the null conditional operator:

OfferOrder pricedOfferOrder = OrderData.OfferOrder
                                       .Where(d => d.Question?.Any(e => e.Price != null) ?? false)
                                       .FirstOrDefault()?.Question;

The problem's root is at the d.Question.Any... and at the FirstOrDefault().Question. If d.Question is null there isn't any meaning on calling Any. Furthermore, FirstOrDefault returns null if no element found. So you can't read property Question of null.

Update

If you use a previous version of C# (where LINQ apparently is available) , you could try the following:

OfferOrder pricedOfferOrder = OrderData.OfferOrder
                                       .Where(d => d.Question != null =>
                                                   ? d.Question.Any(e => e.Price != null) 
                                                   : false)
                                       .FirstOrDefault();
var question = pricedOfferOrder !=null ? pricedOfferOrder.Question : null;

edited Jun 12 '17 at 07:43

answered Jun 12 '17 at 05:28

Christos

53,228
8
76
108

this will be work with `C#` 6.0 or higher – Darshan Faldu Jun 12 '17 at 05:32
@DarshanPatel of course. If OP meets any problem I suppose that he would mention it here. – Christos Jun 12 '17 at 05:34
according to the question "It works fine but when Price of all Question are null" I think the problem is only in FirstOrDefault only – jitender Jun 12 '17 at 05:34
@jitender The code as it is has problem also at `Any`. I don't think that we should take for granted that `Question` is always not null. – Christos Jun 12 '17 at 05:35
@Christos yup your are right I was thinking about the current problem only – jitender Jun 12 '17 at 05:37

score 0 · Answer 2 · answered Jun 12 '17 at 05:29

If you are using c#6 Or above

OfferOrder pricedOfferOrder = OrderData.OfferOrder
  .Where(d => d.Question.Any(e => e.Price != null)).FirstOrDefault()?.Question);

For older version

var data = OrderData.OfferOrder
  .Where(d => d.Question.Any(e => e.Price != null)).FirstOrDefault();
OfferOrder pricedOfferOrder = data != null ? data.Question : null;

Object not set to an instance of an object when using Any()

2 Answers2

Linked