Issue with Any in OData $filter clause.

[adamfairstr]

Hi,

Thanks for this great library. I'd love to see it grow.

I've got an issue with a queries such as:

people?$filter=EmploymentsList/any(o: o/Salary eq 2.5)

Where EmploymentsList is a property on People and is defined as:

   private readonly ISet<Employment> employmentsList= new HashSet<Employment>();

   public virtual IEnumerable<Employment> EmploymentsList 
   {
      get { return this.employmentsList; }
   }

I receive the following error:

"Cannot get collection item type"

Unfortunately, I cannot change the definition of .EmploymentsList and so would like to change nHibernate.odata instead. I can see the issue lies in NHibernate.OData.TypeUtil.TryGetCollectionItemType at this line:

   System.Type enumerableType = collectionType.GetInterfaces().FirstOrDefault(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(IEnumerable<>));

And enumerableType is returned as null.

Unfortunately, my knowledge of reflection isn't brilliant and would need some pointers but would adding a line such as:

   if (enumerableType == null) enumerableType = collectionType;

be acceptable? If it is, I'll get on and write a unit test and send a pull request.

[dsigitov]

Hi!

but would adding a line such as:
if (enumerableType == null) enumerableType = collectionType;
be acceptable? If it is, I'll get on and write a unit test and send a pull request.

I wouldn't recommend doing that. It will totally break the logic of this method.

The problem is that method doesn't handle correctly the case when collectionType is IEnumerable<T> itself.

Instead, change the method as follows:

public static System.Type TryGetCollectionItemType(System.Type collectionType)
{
    if (collectionType == null)
        return null;

    System.Type enumerableType;
    if (collectionType.IsGenericType && collectionType.GetGenericTypeDefinition() == typeof(IEnumerable<>))
        enumerableType = collectionType;
    else
        enumerableType = collectionType.GetInterfaces().FirstOrDefault(x => x.IsGenericType && x.GetGenericTypeDefinition() == typeof(IEnumerable<>));

    if (enumerableType == null)
        return null;

    return enumerableType.GetGenericArguments().Single();
}

It will first check whether the value of collectionType is IEnumerable<T> itself, then it will check all interfaces, so this test will pass:

Assert.AreEqual(typeof(int), OData.TypeUtil.TryGetCollectionItemType(typeof(IEnumerable<int>)));

[pvginkel]

Sorry for the late reply. I'll push a new version to NuGet in a moment with this fix.