Invoking a predicate throws NullReferenceException in condition

Asked Nov 29 '16 at 10:06

Active Nov 29 '16 at 10:13

Viewed 28 times

I have the following method but when I invoke that method I get a NullReferenceException.

public IQueryable<TItem> Query {get; set;}

public void AddCriteria<TSource>(TSource source, Func<IQueryable<TItem>, TSource, IQueryable<TItem>> func, Predicate<TSource> condition)
{
    if(condition(source))
    {
        Query = func(Query, source);
    }
}

I call it using the following line of code.

searchFilter.AddCriteria(searchCriteria, (u,v) => u.Where(p=>p.Field1.equals(true)), p => p.Field2.Specified && p.Field2.Name.Equals(Settings.Default.NameKey));

I'm trying to have a null safe check before apply the condition to the source. Do you know how to do it?

Thank you.

edited Nov 29 '16 at 10:13

asked Nov 29 '16 at 10:06

duknust

That code doesn't compile. Also, how do you call that method? We just have to guess now. – Patrick Hofman Nov 29 '16 at 10:08
What is `Query`? Where do you get it from? – Patrick Hofman Nov 29 '16 at 10:09
The way I call is not important because the null check needs to be here. But I will change the question. – duknust Nov 29 '16 at 10:09
But what do you want to null-check? Why doesn't a simple `if (x == null)` work? – Patrick Hofman Nov 29 '16 at 10:12
@Igor I know what is a null reference but this is not that simple. – duknust Nov 29 '16 at 10:15
2

Yes, it is that simple @duknust – Patrick Hofman Nov 29 '16 at 10:16
No because the condition is not null and the source is neither. The condition applied to the source throws a nullreference but I can't test if one or the other is null – duknust Nov 29 '16 at 10:24
Then you should fix the code in the condition, right? – Patrick Hofman Nov 29 '16 at 10:44

Invoking a predicate throws NullReferenceException in condition

0 Answers0