how to check for NULL values?

Question

User1870205858 posted

I'm new to Entity Framework and I'm getting a null reference error that I'm not sure how to resolve.

In my DBContext class, in the onModelCreating method, I'm binding the database columns to the class that I am using.

My database column is called "cancelled_date" and my class property is "CancelledDate". My query that is returning the data has some records with null values in this column.

Here's my code snippet in the onModelCreating method:

...

entity.Property(e => e.CancelledDate)
.HasColumnName("cancelled_date")
.HasColumnType("datetime");

...

What attribute do I need to add to check for nulls? I tried putting a try/catch around this, but that did not work. 

Any suggestions? Thanks!

Answer 1

User475983607 posted

Your question is not clear.  I assume you must define the CancelledDate as a nullable type in the model.

public class SomeClass 
{
    public Datetime? CancelledDate {get; set;}
}

See the docs

https://docs.microsoft.com/en-us/ef/core/modeling/required-optional

Answer 2

User1870205858 posted

Actually, that DOES answer my question. An oversight on my part. I forgot the "?" to make the property nullable.

Thanks!