Getting Null Reference Exception when there are no records in database table.

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I am getting null reference exception for the following code in the view.

@if (Model.OperatorNotes.ApprovedBy.HasValue)  // null reference exception
{
<div class="row form-group">
<div class="col-xs-2 col-md-2 col-s-2">
Approved By
</div>
<div class="col-xs-10 col-md-10 col-s-10">
@UserHelper.GetUsername(Model.OperatorNotes.ApprovedBy.Value)
</div>
</div>
}

when there are records in the table 'OperatorNotes' no exception is raised.
How should i resolve this? what should i be using instead of '@if (Model.OperatorNotes.ApprovedBy.HasValue)'

Posted 6-Jan-16 23:19pm

sunnykvinod

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Comments

Richard MacCutchan 7-Jan-16 6:15am

You first need to check if any records exist.

John C Rayan 7-Jan-16 7:32am

You could use
@if (Model.OperatorNotes.Count() > 0 && Model.OperatorNotes.ApprovedBy.HasValue).
But can you show us your model structure for OperatorNotes ? It doesn't look right to me.

sunnykvinod 7-Jan-16 7:38am

public class OperatorNotesDto
{
public long OperatorNotesId { get; set; }

public string StatusSID { get; set; }

public DateTime NotificationDate { get; set; }

public Guid? ApprovedBy { get; set; }

public DateTime? ApprovedDate { get; set; }

public bool HasNotified { get; set; }

public DateTime? ProcessedDate { get; set; }

public int Archived { get; set; }

public int Deleted { get; set; }
}

sunnykvinod 7-Jan-16 7:40am

i cant use Count method

John C Rayan 7-Jan-16 7:43am

You have to initialize empty collection if no records in DB. That's the way you have to work in View.

John C Rayan 7-Jan-16 7:41am

So Model.OperatorNotes is a collection. How can you access ApprovedBy property from the collection. You have to go through the individual items and check. Explain to me what you trying to do.

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Richard Deeming · Accepted Answer · 2016-01-07T03:29:00

Try testing the OperatorNotes property for null before trying to access one of its properties:

C#

@if (Model.OperatorNotes != null && Model.OperatorNotes.ApprovedBy.HasValue)

Alternatively, if you're using C# 6, you could use the Null-conditional operator[^]:

C#

@if (Model.OperatorNotes?.ApprovedBy.HasValue)

(Note the extra ? in the property access: OperatorNotes?.ApprovedBy)