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c#linqnhibernatefluent-nhibernate
mohaidar
mohaidar

Reputation: 4276

NHibernate nullability check inside where does not work

I have this code

var x = xId.HasValue ? _xRepository.Get(xId) : null;
var result = _yRepository.Find()
.Where(y=> x == null || x.Ys.Contains(y)).ToArray();

NHibernate breaks on this line .Where(y=> x == null || x.Ys.Contains(y)) where it executes all conditions and it does not stop on the first condition if the value of x is equal to null.

could any one help me to solve this issue.

Upvotes: 1

Views: 29

Answers (1)

Radim Köhler
Radim Köhler

Reputation: 123861

In this case, we can evaluate the x before the SQL is created e.g:

var toFilter = _yRepository.Find();

// should we handle x at all?
if (x != null)
{
    toFilter = toFilter.Where(y => x.ys.Contains(y));
}

var emailAddresses = toFilter.ToArray();

Extend

with an extension like this

public static class MyExtensions
{
    public static IQueryable<T> MyContains<T, TFilter>(
         this IQueryable<T> list, 
         TFilter x, 
         Expression<Func<T, bool>> filterFunc)
    {
        if (x == null)
        {
            return list;
        }

        return list.Where(filterFunc);
    }
}

we can make such filtering at one line

var emailAddresses = _yRepository
   .Find()
   .MyContains(x, y => x.ys.Contains(y))
   .ToArray();

Upvotes: 1

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