How should I handler bool? in expression

Question

I write a Linq-To-Sql syntax is like below:

decimal? sum = UnitOfWork.MorderlistRepository.Select(
    c => c.material_id == Id && c.docstatus_id == 2 && c.is_aborted!=true && c.is_freezed!=true
).Sum(s => s.Qty);

the Select function defined as follow:

public virtual List<BusinessEntityT> Select(Expression<Func<TEFEntity, bool>> expression)
{
    List<BusinessEntityT> bEntities = new List<BusinessEntityT>();
    List<TEFEntity> entities = null;
    entities = _dbSet.Where(expression).ToList();
    foreach (TEFEntity entity in entities)
    {
        BusinessEntityT businessEntity = new BusinessEntityT();
        businessEntity.Context = _db;
        businessEntity.DbInstance = entity;
        bEntities.Add(businessEntity);
    }
    return bEntities;
}

The type of material_id and docstatus_id is int?, is_aborted and is_freezed is bool?.

Now each time when excute to the code

entities = _dbSet.Where(expression).ToList();

I always receive error message

value can't be null,ParamName = 'source'

Why?

You could convert it to `DBNull.Value` if the `bool?` value is null. — rory.ap, Jan 29 '16 at 14:46
Possibly related [to this](http://stackoverflow.com/questions/16281133/value-cannot-be-null-parameter-name-source). — Neil, Jan 29 '16 at 14:48
`value can't be null,ParamName = 'source'` is a common Linq error that occurs when you try to call an extension method on a null value - in your case, `_dbSet`. — D Stanley, Jan 29 '16 at 14:58

score 0 · Answer 1 · answered Jan 29 '16 at 14:55

0

You can manage nullable bool easilly in Linq expression usint the null coalescing operator :

x=> (x.myNullableBool ?? false) == false

The same logic an be applied ot int?

x=> (x.myNullableInt ?? -1) == 2

answered Jan 29 '16 at 14:55

Seb

1,230
11
19

How should I handler bool? in expression

1 Answers1